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Document:	TR-95 Fundamentals Of ReGIS Jul79
Order Number:	XX-A2D47-A4
Revision:	0
Pages:	82
Original Filename:	TR-95_Fundamentals_Of_ReGIS_Jul79.pdf

OCR Text

DEC/TR-&

FUNDAMENTALS OF THE
REMOTE GRAPHICS'
INSTRUCTION SET

(REGIS)

by
Charle’

RESEARCH

AND

Rupp

DEVELGCPMEMT

GFCUP

REVISION

...

April

1979

FEVISION

...

July

1979

Ccoyricht 1679
Equirment Corporation
146 Main Street
maynard, Massacnusetts 01754

Digital

Keywords:
Graphics
REGIS
ASCII Interface Standard

page 2

REGIS FUNDAMENTALS... Rev, 1

PREFACE

This document summarizes a collection of ideas concerning
of the cdefinition of a
an 1instruction set for the communication
graphic image vetween a comouter and a peripheral 4gqraphic
device,

Although

it is felt that this definition is unique in

its apility to support a

wide

variety

dissimilar

araphic

devices in a wide variety of application environments, REGIS'
(#hnich stands for the Remote Graphlic Instruction Set) 1is felt by

the author to represent a natural evolution of existing device
by several
specific interface protocols used on devices produced
manufacturers.

The principal gcals and assumptions of REGIS may be

follows:

all

future

graphic

terminal

contain

devices

will

language

svntax

micro=processor computing elements and therefore are able to

interpret

rich

user-

reasonaple performance,

2.
»

stated

oriented

with

A majority of remote graphic devices communicate with a
over serial communications 1lines using ASCII
comouter
cnaracter codes. REGIS 1s therefore specifically desianed
to be embedded iIn the ASCII bprotocol environment anrd
this
contains special features to efficiently utilize
communication media.

To aminimize the number of different langquage syntaxes which
and svstem designers must work with, REGIS {is
users
- specifically designed to bte usea both as a lire protocol and
a 4graphic file syntax. Ir addition, REGIS is sutficiently
"tnglisn Level"” oriented as to pe useful as orint string
constants from a hiagh 1level language which has no direct
graphic device support.

REGIS is not meant to be & replacement for bigher level
apolication oriented graphic languages, such as the oroposed
SIGGRAPH CARE standard, out rather is meant to be used as
tne “"object code" 1level language translation from such a
nigner level image definition. PEGIS therefore srecifticallv
addresses the attributes of the graphic device itself arc
viewing
igqnores such hignher level language 1ssues as
transformations and "reale-world" coordinates,

REGIS’s aporoach to instruction level coce

transovortability

pased upon the concept that the wmajority ot the
is
information content of a grarnic image mray be defined by a
few common graphic instructions and tnat the specific
actriputes and capapilites of a grachic- device may te
transforred or ignored »y a dissimilar graphic device
vitnout destrcying the essential intformation content of

image

the

drawn,

Ine onurcose of this report is to

present

the

fvnaamenrtal

conceots of REGIS and to dlscuss the underlvinrng assumntions and
tradenattfs w~nicnh crharacterize REGIS.,. This report should not te

REGIS

FUNDAMENTALS...

Rev,.

considered

hopefully

definitive

serve

for

the

develooment

common

Page

srecification

voint

for REGIS but will
discussion
in
preparation

specification.

This
report
summarizes
both
formal
and
informal
work
carried
out
bpy
a
targe
number of lndividuals within the DFECorganization and principally grew out
of the discussions of
the
Common
Graonics
Command Set Committee.
Special mention should
be mado
e
f the efforts
of
the
members
in
the
Research
and
Development
Department, the Computer Aided Lesign
group and the
Video Products Group which directly
contributed to
the
content
and substance of this report.
REVISION 1|
'This
as

revision

organizations
North

and

areas

reflects

function

and

Bob

refinements

comments

particularly
Fleischer,

the
The

contained

within

string

JNumeric

®acrographs

4.,

A
REGIS
compatible
device
coordinate definitcion.

Pilxel

may

may be

size

adjust

and

guideline

for

Temporary

writing
text

ll,

ootions

Tne

"="

and
to

May

use

size

Don

summarizes

the

list

the

space

first

have

are

now

position

gption

numeric

for

now

character,.

clearinc,
default

orlv

circles

instead.

has

been

parameters

for

interactive

allowed

color

anc

enable/disacle

instruction

definition

"standara"

qualifiers

read

The

without

dDrocess

clarifieqa,

Powers,

doubling.

instructions.

cursor

"+"

multipliers

assumed

The end point
clarified,

changed

10,

the

curve

and

DEC

Tom

screer

have

ore

added,

document

several

the single quote
"°"
or
delimiter character mav still

delimited

redefined

parameter,

comments

original
from

either

constants

the

following

change:

Strings may be delimited by
double quote *"’ character,

received

aaded

text

the

arcs

syntax

allow

has

access

teen

vector,

has

teen

has

been

drawing

devices.

arev-scale

maprcinc

has

treepn

REGIS

FUNDAMENTALS...

Rev,

Page

CONTENTS

1.
1.1
1.2

103
1.4
1.5
1.6

20
2.1
2.2

2.3
3.

3.1
3.2
3.3

IRGTRODUCTIOBJ
SYSteM MOdEl
Graphics

LN BN SR BN BN X BN BN BN BN BN BN BN B BN B R BN B BRI 3 BC B B B N BN BN )
ceecevaccocscccesncscsecnconcnsss

Lancuage

ACCeSS

POINLS

cceeccecccose

-REGIS SCODe Of aPDlicatiOfl
e 0000000V OIOSTSES
REGIS Qverview
L AN B B AR BN BF B B BN BN BN BY BN BN N BN BN IS B NN BN BN N I
Example Image Generation
.ceecececccccscsececse
Range

o0f

Intended

PEGIS PHILOSDPHY

DeviCeS

10
11
12

ccocccccccecvcccee

LA IR B BE BN BN BN BN BN BN B BN S A NN OBE BN B BN NN BN NN N W )

Transportability CONnCeptsS
eceececcccvcccsssesee
Syntax Considerations
..ccccececcccccsccnces

Semantics Considerations

Lcceccccecccccccscs

THE BASE LOGICAL GRAPHIC DEVICE
Viewing
Viewing
Assumed

6
7

16
18

cceccevceccce

..ccceccecescccaccee
..cececccececcccccccses
SCeNArio
ceececcocees

22
25
26

LA BE B BE BN BN BN BE BN BN B BN SN BE BN NE OBX BN BN BR BN BN BN )

® % 0 008 O 0 Q¢S OO0 OO O CO OO 9 OO OO OO OO OSSO TDDPEE
Grammat
LK BN BL OBE BN BN BN BN BN BN BN BE BN BR BE BN B IR BN BB BB R N B B

Area Definition
Point Attributes
Image Generation

REGIS GE&ERAL

SYNTAX

4.1

Alpnabet

4.2

General

4.3
4,4

M3Crograph StrinNgsS
POSition ArQUMENES

4.5

extensipllity

.cecceecccecccccccccese

5.1
S.2
Se3
5.4

Screen INSCLrucCtion
cecececececcsccsecscosocsncacacs
POSition INSLrUCLiON
ceececvccccccnccevscscnsece

42
45

S.5

ariting Attributes INSCIUCLION
ceceveccceceoes
vector Drawing INStruction
.eceeececececesceccses

curve

49
OS1

S.6

Text

THE

Guidelines

Drawing

INSTIrUCLION

INStruCtion

EXTENDED

LOGICAL

6.1

Dlmensj-onal

Screens

6.2
6.3
5.4

Text

0eS

6.5

7.1
72

7.3
8.

.cececccecccessccccscccnsee
.ceeeccccccsccscccccccasccs

Gray=Scale

cceccvccccccsoccce

.ceceececcccvecacecoccscecss

DEVICE

33
3%

D54

ceececoceccececcsecse

L AL BN BN BN BN BK BN BN BN BN BN B N B BN ONE BN NN BN BN B NN
.eeccccocoscccscncsssensss

and COlOT
Attributes
LN B BN BN BN BE BN BN BN BN BE BN BN BN BN NN I NN R R R NN W Y
Aread ACELriDULES
.cecececcccccovccccsancccncace
Animation and DVNAMICS
cceecevccccccccscccace
iJser 1nteraction
..eecccccccccccsccccccascse

STANDARD RASTER DISPLAY EXTENSIONS

ceeecscses

OI
63
BS
OB

kaster

Screen

Instruction

Extensions

ceececeese

Raster

writing

Attributes

Extensions

Raster

Text

ececececese.

ceeesesccevccecscssce

INSTALLATION

EXCensSioNS
ENVIPGOGNMEMTS

..cecececcccccccsccea

715

REGIS

l.
2.
3.
4.

S.
6.
7.
8.

10,

11,
12.

13,
14,

FUNDAMENTALS...,

Rev.,

Page

FIGURES

Graphics System Block DI1aQram
..eveeceecceeoee
EXample GraphRics IMAGe
ceeececcvcoccccccncnes
Example Graphics Code SEAUENCEeS
eevecocceece.
"‘Eta-Lanquaqe Notation
..‘.OQ..O..0.0...O.QI.

REGIS General Syntax
C...‘QO...'.Q...OO...Q..
REGIS Basic Syntax E£1emMeNtS
..ececcccecccceeas
Summary of REGIS Base INSLructions
.eeeceeceee.
Vector

Curve

InNStrucCtion

INStruction

Summary of

Standard

Intensity Parameter
Extended Vector and

Extended
Extended

TeXt
Text

EXAmMPLleS

EXamPleS

Raster

.seececceccescccees

..cececceccccescee

Extensions

..cee..

Summarvy
sececsssncccccese
Curve Examples
ceccsccccsse

PAraMELOIS
ceceecceccccosccceces
Examples
cecccsceveccccscssccecas

8
13
14
31

32
40
41
52
57
67
DB
14

77
19

REGIS

FUNDAMENTALS...

Rev.

Page

1.0

INTRODUCTION
The

level

Remote
portatle

meant

principally

images
device,

Instruction

graphic
to

graphics

stored as

Set
(REGIS)
1Is
definition
acproach,

image
used

between
a
host
REGIS
also
has

(bounded)

image

Graphics

for

the

communication

computer and a
applicability

svstems

sequence

any

gJraphic

remote "smart"
to
tightly-

context

which

characters.

device
Although:

graphics
coupled
graenic

Tnils
including

led

brietf

report describes the
fundamental
concepts
of
REGIS
the
wunderlying
assumptions and tradeoffs which have
its.development.
The paragraphs in this section
give
a

overview

c¢f

REGIS

various

uses

structure,

tne

range

devices

illustrative
sections

for

examples

discuss

the

"logical graohic device"
specific
syntax
and
instruction set.

1in

which

REGIS

terms

FEGIS

within

REGIS

i{s

the

assumed

that

structure,

designed

instruction

philosophy

upon
which
semantics

REGIS,

REGIS
of
the

system

sequences.
the

and

Later

conceopt

1is
based
«currently

the

used

and
the
defined

REGIS

FUNDAMENTALS...

Rev,

Page

1.1
SYSTEM

TMODEL

Figure 1
graphics

the

illustrated,
host

illustrates
svstem
in

the system consists

computer

system

consists
device,

of various
The
term
graphics device

the
possibly

the assumed general bleck
diaaram
which
REGIS is meant to be used,.,

lowe-speed

which

parts

the

parts:

user’s

communications

(not

all

(1)

the

view

point

software modules and (2) the
"remote" here refers to the
is
attached
tc
the
host

remote graphics
assumption that
computer

link,

The host computer system is
major

two major

from

of
As

assumed

wnich

may

consist

present

four

particular

system):

Grapnics

application

rackage(s)

« allow

the

user

access

the
qgraphics
capabilities 0f the remote device in terms of
syntax and semantics
appropriate
to
the
user’s
intended
application,
For
example,
a
data plotting package which
accepts

tavles

plots
of
example, a

prepare

allows

the

user

construct

flowchart

diagrams

for

3 second
uyser
¢to

technical

and

use.

level language(s) = allow the user to genrerate
grapbhric
images
of
sianificant
ccmrlexity
requiring
alcorithmic
definition andsor images recuiring dynamic
changes
to
the

image,

Text

files

graohic

= allow

{image

avplication

shown

standard
4,

and

tignh

graphic
3.

data

variety

managerial

varying
types
based
on that data.
As
flowcharting onackage which
allows
the

OQOperating

the

user

generated

store

the

high

deftinition

1level

program

packxage and later cause that graphic 1imace to
the
same manner as printing out a report file

text,
system

may

oroviage

supoort

the

craphics

user

in
the
general
case
by
converting
the
gararhic
imace
definition orovided by the other software
o0
the
reauirec
protocols
necessary
to
drive
one or more remote qraphics
devices,

REGIS

FUMDAMENTALS...

Figure

Rev,

GRAPHICS

Page

SYSTE#

BLGCK

DIAGRAR

F--—-—--—-—C—-—-—--—-—-—“l- ————— —————

)

APPLICATION
PACKAGE

)

‘

HIGH LEVEL

GRAPHICS TEXT FM——

FILE

boon -

A
SYSTEM

[

—— — =l
OTHER

COMMUNICATIONS
INTERFACE

GRAPHICS
DEVICES

;

pEVICES b=

GRAPHICS

|
|
|

DEVICE

GRAPHICS

figfi

INSTRUCTIONS

PHYSICAL
DISPLAY
DEVICE

|
|
!

!
|
!

REGIS

FUMDAMENTALS...,

The

remote

following

basic

Rev,

graphics

Page

devices

are

assumed

have

the

structure:

Local

processor =~ interprets the graphics
1image
definition
provided
by
the
computer into a form which can be used by
the hardware image generation part and transfer
information
concerning operator entries to the host computer,

Hardware

Image

Generator

electro-mechanical

gives

the

flate-bed

circult
3.

visible

Operator

In
longer

host

the

plotter

the

image.

and

the

digitals

gqgraphics

analog/

device

with

which

The pen=-movement mechanism
CRT

device

the

communicate

tube

are

with

refresh

examples

device

memory

this.

devices

1in

the

aoplication

either
1local

program(s)

computer,

collapse

system

generally

graphics system whicn ‘allows the user to
directly with
the
1local
processor
for

a bounded system,
visible
to
the

generally

the

a raster graphics

interactive
communicate
the

graphic

1nterface(s)

overations

portion

remain

into

the

the
user

communications
interface
1is
no
and the local and host processors

single

same

processor.,

illustrated

The

other

bounded

for

parts

system,

1.2
GRAPHICS

- least

LANGUAGE

8ased
six

developers

POINTS

on the above assumed structure,
the
system
has
language access voints of interest to the user’s
of

Graohics
data

ACCESS

such

system:

application

plotting

languages

package

reoresented

at
anc

or
the

the

= such

plot

constructors

oprocosed

SIGGRAPH

commands
chysical
COFE

imacges

dgraohics

stangdard.,

High level larncuages
three possinle wavs:
1.

Direct

drive
using

allow

access

character based
string
c¢onstants

grarhics

semantics

communication

output

orotccols

throuch

"PRIMT"

statements.,

Graphics

sub-=routines

gmbedded

grarhics

3as

language

ather

accessecd

proarammed

statements accessecd
caranilities.

text tiles = the syntax of how the
stored
as
text for later communiraticr

the

calls.
same

Grapnhics

graphics

device,

the

manner

irage
agrarhics

REGIS

FUNDAMENTALS...

Communications

Page

1Interface

the

syntax

sequentially

the

grachics

the

commands

sent

Graphics

hardware
instructions
=
refer
to
signals
generated by the local device

digital

L& control

Rev,

User

graphics

sequences

user

the

hardware

entries

£or

local

commands

image

required

the

addition

use

the

graphics

device.

the
assured
processor to

generator.

refer

control

speclalized
to

the

entry

syntax

application

programs,

1¢

the

software

1.3
REGIS

SCOPE

APPLICATICM

The

natural

language

aquestion

access

points

general

purpose

thls

breadth

clearly
of

“personality"
other

hana,

language

1is

grachics

of
course
bpe
which satisfied

impractical

oetween

the

wnich

will

accepot

standard

for

language
to

and

tne

communications

summary

then,

Graphics

cases.

and

intertace

whetner

The

"semantic

communications

The

syntax

oriented

file,

upon

graphics

the

points.

found

1in

the

araohics

aware

of also is
standardized

when

and

dictated

stanagards.

against)

purvose

intent

the

CORE

high

Jlevel

of REGIS

rather

least

the
extrapolation,

grachic

REGIS

points

constants

rprint

by
lanquage

for
a

commands

image,

used

beth

for

remote

the

and

from
high
level
statements
or tlre
crograms having
emtcedaed

grarhcs

remote

for

string

graphics

system

differences -

existina

commands.

wculcd

but
considering _the

a
few
apolied

agenerated

cculd

different

the

user

should

also to
be
used
at
other
graohics
the system wnhich are principally basec¢

orotocol"
line

have

to
have
lanquages

representation

the

1language

semantics

compilation of hign level
graphics statements.

aimed?".

and

May

above

impossible)

number

the

arelication

least
not
argue
aoolication
program

1instruction

languages

not

tased

following grapnic language access
Closely=coupled graphics svstems:
1.

ugcon

(at

syntax

character

yser

desire
special

it is the desire of REGIS
language access points in
upon

larce

the

sub=routine

attact

set

different

hopefully
here

use

(it

aprlications

relatively

syntaxes

aoolication

based

range

instruction

undesirable motivatinag a
language approaches with
By

arises

"what

very
nice if one instruction set
the requirerents of all points cf

grapnics

the

which

access

graphics

when

serial

nased

cevice.

stored

character

Page 11

REGIS FUNDAMENTALS... Rev. 1
1.4

REGIS OQVERVIEW

in
d intended utilization of REGIS out
the
Having nov¥ establise
“ith
e
ariz
summ
hs
the following paragrap
a grapnhics system,
ons the general
secti
later
in
n
give
n
atio
ific
the detailed just
.
syntax and semantics of REGIS instructions

ot characters based upon
REGIS instructions are sequencesutin
g systems. That is, the
an alpnabet comron to most comp
A
tuation characters.
alphabet consists letter, digitingandthepunc
ence
sequ
a
ce
devi
hics
grac
grachic image is darawn by send
abet where the general
alph
this
on
d
base
all
ONS
of INSTRUCTIC
LETTER denoting the tvre of
format of each instruction is ana KEYarcitrary numcer of instruction
operation to bde performed and
associated with a
ARGUMENTS which have a prescribed meaning inwhenREGI
S are prietly

KEY=-LETTER. The six basic
defined as follows:

instuctions

to
ER "S" = causes operations such
Screen Instruction = KEY-LETTenti
area
ing
view
cle
visir
re
be opertormed atfecting the
e,
as erasing the irmage in preparation of drawing a new imac
es all
ion - KEY-LETTER Py"® = caus
2. writing Attributes Instruct
imace
tre
ruct
cost
to
ions
the follow#wing drawing instructern, color and sc¢ torth)
using the attributes (line vpatt

1.,

given oy the arauments of the instruction.

drawina
LETTER "P" = causes the vert
3, Position Instruction - KEYical
als/
zont
nori
ific
spec
a
orocess o commence from ,
position in the drawxing area

= causes 4 straight line
Vector Instruction = KEY-LETTER "V"
to oe drawn between the current position and a new position
specitied by the instruction arguments.

§.

causes a circle, arc,
cCurve [nstruction = KEY=LETTER "C" n = base
d upon the arauments
draw
be
to
e
or general curve imag
of the instruction,

es a sequence of
Text Instruction = KEY-LETTER n"T" 1in= caus
a manrer based uvoon thre
text c¢naracters to be draw
arguanents of the ijnstruction,

Tnere are four general tyges of arguments used in REGI

writter within
strincs of characters cate
1. Position arguments are
changes te
rs mf" and "1" which indi
tne oracket characte

tne norizontal and vertical writing position.

rip
characters written vite
s are strings of angd
2. Option argument
er
mwarn
some
in
")" which
esis characters "("

tne oparentn
ruction carries out 1ts
modity tne way in whicn the axinst
is the
The synt of the oection strincgs octi
intended opurpose,
on
on,
reas
same as for instructions and for rhis
nse.
arguments are also called supe=instructio

REGIS

3.,

FUNDAMENTALS...

Text

strings

are

Rev,

Page

character

sequences

contained

within

the

single
guote character "‘" and are used when a character 1is
itself an argument of an instruction as in the case
o0of
the

T<XT

instruction,

Dligit

characters

specific

refer

generally

the

eight

neiaghbors

position.

The principle hypothesis
instructions and thses simple

of REGIS is that these
six
rtasic
arguments are sufficient to define

most

tne

information

the

graphic

images

interest
to
most
of
the users of graphics systems.
The fact
that Instruction set is terse in nature is based upon the desire
for
a
relatively efficient coomunications protocol and that it
is
assumed
that
most
graphic
1images “will
oprepared
usina
application
programs.,
REGIS as a language {s still high enouah
in
1level
that
the
graphic
1image
definition
{is
still
not
completely
<critical
and
so
specific
that
different araphic
devices

nave

some

instructions
to
reasonaple chance
device

and

degree

freedom

maximize
their
own
of
gqgraphlic
1image

{in

interpreting

features and
vportability

the

thus allow a
between
onre

anotner,

1.3

EXAMPLE

IMAGE

GENERATION

Figure 2 illustrates a simple grachics image
diamond ,circle and graohics text.
The second

2 illuystrates tne
image.
note tnat

consistina
of
cvart of figure
REGIS instructions required to
generate
this
a REGIS instruction generally mav have several

arguaents.

Figure 3 illustrates
program
seguences
11llustrating
source for the generation of these REGIS instructions tased
the three basic aporoaches to accessing
dgraphics
from
A3
level
1language (in this case, a langquage
of RASIC) and the crogram sequences
for
based

1300

the

SIGGRAPH

CORE

having tre
gererating

c¢crarhics

tne
upon
ricgh

personality
the
image

stanrdard.

1is

surorising cthat the direct use 0f REGIS in PFRINT staterents
tas
comparable
*"readability®
¢to
the
other
aprcroaches.
This {is
deceiving however due to the
simplicity
of
the
1image
4drawn.

REGIS has no viewing transformation, three-=cdimensional image and
segment capabilites as found in the SIGGRAFH CORE ana of use
1in
higher level applications work.
The assumption ¢f REGIS is that
these
caoapilities
are
translatable
to
secuences
of
REGIS
instructions,

REGIS

FUMNDAMENTALS.,..

Figure

EXAMPLE

CIRCLE

REGIS

Rev,.

AND

instructions

GRAPHICS

IMAGE

DIAMOND

for

the

acove

image:

P(100,100]
v[200,0]1(300,100])(200,200}(100,100]
P{200,100] C(+100]
PL150,150] T(S2) °CIRCLE AND DIAMCWD’

Page

REGIS

FUNDAMEMTALS
... Rev.

Figure
d.

Using

EXAMPLE
REGIS

Page

APPLICATIUON

Directly

LEVEL

GRAPHICS SEQUENCES

statements

100

Gis,

110
120
130

PRINT
PRINT
PRINT

"*Vv{2006,0]1(3G0,1060]1"
"V(200,200](C1G60,100])"
"P[200,100]C(+100])", GOS

Note:

The

to0
oy

string

"P{100,100]"

constants

G1s

and

G0S

refer

character seaquences which are defined
some mechanism at the begining of the

orogram and cause the qgqraphics crocess

be turned
device,

Using

Graphics

100
110
120
130
140
150

¢.

and

0off

the

gracnics

Sube-routines

CALL POSITION(100,100)
CALL VECTCR{(200,0)
CALL VECTOR(300,100)
CALL VECTUR(200,200)
CALL VECTOR(100,100)
CALL CIRCLE(200,100,100)

Enmpedded Grarhics

Commangs

100
110
120

DRAN
DRAW
DRAW

100,1007200,0;
300,100;260,2G0:;100,100

SIGGRAPH

CORE

Statements

206,160 CIRCLE

MOVE.ABS.2

100

(100,100)

LINE_ABS.2 (200,0)
LINE_ABS.2 (300,100)
LINVE_ABS.2 (2€0,200)
LINE_ASSL2 (100,100)
POLYLINE_ABS.2 (X,Y)
dote:

The

arrays

contain

the

spaced

points

generated

and

are

coordinates

on
cy

assumed

a circle
some

closely

program

would
segment,

REGIS

FUNDAMENTALS...

Rev,

Page

range

1.6
RANGE

QOF

INTENDED

REGIS
pboth

DEVICES

ambitious

"softe-copy"”

its

(temporary

attempt
record)

cover

and

record) remote graphics
such devices include:

devices.,

1.,

Flat-bped

and

plotters

2.,

Drum

3.,

Photoe=plotters

includinag

Monocnrome

color

Storage

Stroke

Flate=panel

Matrix,

monochrome

monocnrome

and

CRT

and

color

encoded

particular
whicn does

computer

incomplete

list

CRT

output

microforms

devices

display devices

thermal

possibly

(permanent

devices

grapnics

essential

broad

plotters

raster

and

tne

tasic

set

informacion

device are
not have a

such

electrostatic

The principal concept of the
images 1is that the essential
be

color

"hardecopy"

plasma

panels

hard-copry

devices

transcortability
of
information content of
cf

instructions

content

and

1lost

transformed (¢r even
particular attribute

RFGIS
based
an image can

that

1little

attributes

igrored) pv
cacability.

device

REGIS

FUNDAMENTALS...

Rev,

Page

2,9
REGIS

PHILOSOPHY

This
terms

defined

section describes and discusses the rationale of REGIS
of
(1)
the approach to allowing an image originally
.

for

graphic

one

(2)

concepts

the

ASCII

handling

graphics

device,

the

to
be
drawn
instruction set

the

instruction

character

dissimilar

the

device

called

code

device

“semantics"

syntax and

conventions
attributes

on
a
dissimilar
"transocrtability"

the
and

and

crientation

(3)

conceots

cavavilities,

referread

REGIS.

2.1
Transportability
The
3

desire

sequence

images

image

the

definition

graphic

dissimilar

summarize

2.1.1

Concepts

REGIS

APPLICATION

transportaoility

instructions

graphic devices.
approach

FREE

this

draw

The

followinga

transportability,

geometric

contain

any

terms

does

not

other

rule

scecific
the

real

and

include

ohysical

constructions

wnich

viewing

generallv

things.

instructions,
whicn

works

package.

usetul

Instead

with

bar=qrapn

this

can

way

abstract

images

manner,

REGIS

orimitives

supoort

REGIS
syntax

every

Jevice

interpret
mean

all

using

all

anvtning

parameters

are

EXTENS1UNS

categorv

the

rarameters,

the

in
All

higher

ucon
rot

level

sequence

not

turder

data

not

have

such

data

image

that

does

olottirg

not.

required

1instruction

craracter

grammar,

and

base¢
are

REGIS

w~hetner

these

languages

REGIS

agplicatijcr
plotting

built
for

the

into

REGIS

information

terms

PEGIS

based

REGIS

CPkn

axis
sare

must

cefined

RASE

devices

this
and

STANDARL

concept,

qgrazhic

irage

‘irstructions
are

is,

seguences

instructiors

catedory,

That

completely

character

cateqgorv.

REGIS

araochic

set

RFEGIS

BASF

instruction

"rarse".

seaquences

content

the

general
to

those

Semantically,

separated

essential

definaple

are

devices

cossible

instruction

should

IMPLEMENTATIOM

instructicns

wnicn

general

BASE

assumes

REGIS does

similar

MANDATORY

brasec

interpreted

presenting

REGIS

reason,

2.1.2

and

the

are adequately supported
simulate
these
features .by

¥hich

oaragraphs

{n
apolication.
For examcle, £EGIS
transformation, hidden line removal ana

Capabilities

and

compass

capavilirties

semantics

capabilicties

allow

looking

PRIMITIVES

REGIS impolements a set g: drawing primitives

common

similar

reqguired

most
1is

ara
to

REGIS

FUNDAMENTALS...

interpret
addition,

Rev.,

Page

these BASE capabilities
users who know ahead of

as faithfully
time that the

as possible,
image
they

1In
are

defining
s
to
be
used
on
several
different
devices
are
encouraged to use only the BASE
REGIS
capabilities
to
ensure
maximum
transportability.
For
example, color is not a common
attribute of every graohic device, and for this reason the FEGISBASE
1s "color-plind®.
This works out well in practice because
color does not normally
carry
essential
i{nformation
content,
Put
differently,
users
should
avoid
wusing
c¢olor
to relate
essential information in the context that that same
information
is not also implied by monochrore boundaries or patterns.

EXTENSION
STANDARD
of
categories
several
are
There
capabilities,
including
very
high resolution devices (such as
ohoto plotters) and raster scan display devices (including color
CRT
displays).
The
intent
here is the same as tor the REGIS
BASE.
That is, all CRT GEAPHIC
devices
of
aporoximation
the
same
resolution are expected to implement the full range of the
STANDARD

fully

RASTER

EXTEMNSIONS.

This concept works tecause
parse

the

general

all

devices

instruction

are

syntax,

recuired

Therefore,

capapility in one of the extension sets
is
simply
ignored
or
transformed
to
&
simpler attripute in a device for which that
capaplility

2.1.3

does

not

FIDELITY OF

exist.

INFORMATICN

PRESENTATION

Devices are allowed
varying
levels
of
fidelity
in
presentation of information imelied by REGIS irstructions on
oasis of maintaining reasonavble performance while maximizing
translation
of
an
instruction sequence,
The ageneral rule
determining tne allowed
degree
of
1loss
of
fidelity
are

the
the
the
for
as

follows:

Low resolution /monochrome devices are allowed the
4Jreatest
degree of latitude in aporoximation the information contert,

In the limit of A drawing a very detailed image with a larce
information
content
(exceeding
the intorration content of
the simple device) essential information may te lost,

Higher

resolution

degree

svecialized)

(and

devices

fidelity of

presumably

are expected to

excensive

implement

0or

prore

the hichest

information presentation,

One of the reasons that tnis acproach should
work
{s
the
assumption
that
images
are
crepared
on lecwer resolution for
later output on nigher resolution (possiply slower, usually more
expensive)
devices
or that a3 nigh inforration content imace is
prevared directly for the high resoluticn device.
Farely
wculd
an
image
prepared
on
a
bhich resolutior device be drawn on a
supstantially lower resolution device except perhaps for "quickechecking"
or
stherwise
the user must ne willing to accert tne
ne
of
result
a
cossible misintercretation of intermation as
lower fidelity of reocroducticr.

REGIS

FUNDAMENTALS...

2.1.4

CRITICAL

Rev.

DEVICE

Page

PARAMETERS

The
third
major
concept
1in
allowing
maximal
image
transportapility is the use of critical setup parameters defined
once
for
each
1image
and
placed
at
the
bpeginning
of
the
instruction
sequence
for
that image definition,
Thus, in the
worst case the user might have to
adjust
these
parameters
to
achieve

maximum

As an example
the
user
to

image

fidelity

of such
set the

definition,

physical

range

graphic

imace,

a critical device parameter, REGIS
range of X-Y coordinates to be used

the

reproduction

allows
for an

These presumbly would be
values

device

which

set
the

to
user

the

actual

mostly

uses.

These range parameters could be adjusted to maximally utilize
a
dissimilar
1low
resolution device tut presumably would not nave
to adjusted for plavin the
same
image
on
a
hiagh
resolution
device,

2.2
SYNTAX

CONSIDERATIONS

2.2.1

Character Codes
REGIS

character

1Is

opased

alpnabet,

ASCII=96

character

whicn

note~

does

not

on
To

set

(or

be converted
this rule is

ASCII=S96

environments

the

between

of
convention,
letters
with

letters #ill
exception to

common

have

translatable

differentiate

a
matter
uopper~case

the

support

ASCII-128

ana

ASCII-128

have

onlv

the

set

such

BCD

character

upper

wnich

character

lower

case

set)

REGIS

letters.

REGIS
will
be
defined
the
understanding
that

2As

in terms of
lower
case

to uppoer case £for interpretation.
The
that lower case
letters
will
remain

lower
<case in a quoted string for environments which ¢éo support
the ASCII-128
alpnabet,
The
selection
of
ASCII
for
PREGIS
instructions
is
basea
first
on
the
desirability trhat REGIS
instructions be human- readavle (at least
to
the
deqgree
that
assembly
language
<code
s
readable)
and
secondly
on
tne

presumption
use
ASCII
easily
code

accessinle

(such

2.2.2

ASCII

codes.,

ASCII

To
an

that a majoritv of systems
directly
as
their
base

Control

avoid
oased

All

writcen

means

EBCDIC

many

for

the

B8CD)

REGIS

translation

graohics eitrer
or oprovide sore
their

{{nternal

ASCII.

Codes

problems

environment,

the

REGIS

instructions,

using only

wnich use
text code

rossible

when

does

use

not

carameters,

anada

orintacle character

usinaga
any

PEGIS

ASCIlI

extensions

sets

from

cortrel

carn

ASCII=%n

REGIS

FUNDAMENTALS...

2.2.3

Syntactic
The

grammar

level

Rev.

Relation

Page

Higher

Level

REGIS

general

syntax

based

which

should

make

easily

languages

Languages

simple

generated

and user application packages.
the
REGIS
instruction
types
have been kept
SIGGRAPH
CORE
to
allow
simple
and
implementation,

2.2.4

Use

"PRINT"

The level of
high
enough that
of sucn languages
do

not

directly

(althougnh

support

encoded

point

graphic

terse)
as

the

devices

allows

coding,
usual

(scientific

decimal

notation)

Communications
The

level

Line

REGIS

reasonaole

reasonably

particular,
integer,

strings

languages.

that

high

In
particular,
very close to the
straightforward

instructions and parameters has been set
the use of REGIS directly in tre PRINT strings
as BASIC, FORTRAN, and PASCAL on systems wnich

and

2.2.5

parsed

common

REGIS

arguments .are

these

easily

strings

admittedly

floating~

clear

number

fixec-point,

cenerated

Efticiency

instructions

performance

may

has

peen

set
obtaired

low

enoudh
even
at

so
low

transmission rates.
It is for this reason that the
"macrograoh
string”
nas
©opeen
included
in
the
RKEGIS
base
to
allowirng
repetitive string seauences to be defined once and then referreq
to

D0y

REGIS

name

separators

REGIS

has

and

characters

2.2.6

any

allows

times.,

format

multiple

awareness

are

Altaougn

line

and

for

this

recuires

rason

nox

instructions

per

boundaries,

since

also

that

instruction

"line"

(in

ASCII

ignored).

not

capture

minimal

and

the

interchanges

string

and

auto-conversion

the

imolemetation

contant
of

lower

this

2.3
Semantic

possible

amongst

personilizations

«ith

numeric

personality

attempted

langquage
users

free

fact,

centrol

Hian-ievel Language "Personality"

compatiole
has

number

generalliy

Considerations

all

define

hiagher

essence

allow
of

concept.

tnhe

upoer

a
comcletely
languaces, REGIS

many

the

higher

level
learning ey
constructs.
Comkon

most

syntactic

constructs
case

level

rarid

ignorinc

case

are

nlanks

examoles

REGIS FUNDAMENTALS... Reve. 1
2.3.1

Range

devices

REGIS is intended
display devices:

for

use

the

Low

nigh

resolution

flat=-bed

Low

high

resolution

rotary

Above

monochrome

5S.

Full-tone

Storage

Stroke graphics devices

aonochrome

Page 20

plotters

with

binary
and

CRT

binary

raster

color

raster

range

araphic

plotters

CRT

following

full-tone

color

divices

CRT

devices

Plasma

devices

"Future" x-y addressable disolay devices such as LED arrays,

LCD

disvlays and

Electro-luminescent

disolavs.

It {s felt that the REGIS BASE 1instructions adeguately defires a
common denominator of tnese devices, and that the EXTEMSIOMS and
OPEN

categories

current

and

adegquately

future

access

the

unicue

capabilities

devices.

2.3.2

Position

Addressing

specific

point

assumed

the

representable

of numbers and that the
the
purpose
of
c¢code
increment is assumed to
REGIS
BASE
(if indeed
and otnerwise definable

viewing area of
by

X=Y

graohic

device

(horizontalevertical)

rpair

viewing area is rectangular in shape for
transoortabilicy.
The
size
c¢f an X=-Y
ve defined by the device itself
in
the
the device is able to Zefine it at all!)
by user supolied parameters in the REGIS

extensions.,

2.3.3

Semantic

There
BASE.
In
derivable

are

iLefaults

generally no

fact,
all
from
user

default

oarameter
supplied

parameters

ranges
screen

reauired by a
ccordinates

the

PEGIS

device
wnich

are
are

transformed

to nhysical coordinates bv the cdevice.,
An excection
to this is the size of "standard characters" in the device «hich
Wwill
naturally vary as a function ot cnysical qgesigon cecision .
To accommodate such variances, REGIS allows tre user to "adjust"
these

parameters
so

possible

#nat

the

that
user

the

actual

expected,

visual

result

clcse

REGIS

FUNDAMENTALS...

Devices

inmplement
affect tne
much

which

does

must

which

not

values
display.
the

have

assumed

Page

implement

default
visipble

possiole

Rev,

REGIS

for

visual

these

each

are

required

all such semantic features which
These defaults will aporoximate
as
impression

visual

and

extensions

every

the

enhancements

time

the

image
and

screen

tnese

clear

device

defaults

operation

performed.,
For
example,
the
default
writing
pen
for
a
plotter
1is
obolack
(althougn
it
1is
white
or green for a CRT
device!) as opposed to some hue capability (unless of
course the
divice
naturally
only
has
a single hue writing capability ..
green for storage tubes and orange for plasma displays).

2.3.4

Range

apolication

For the purpose of
arbitrarily broken down

this
into

Data

Presentation graphics

1Image

report,
graphic
three categories:

images

will

plotting

processing

The

first two catecories are
sometimes
referred
to
as
"data
representation
graphics®
and the later category referred to as
"inherently
4qraphic".
The
1intent
here
is
to
establish
a
framework
for the range of aoplicability of KREGIS.
Contrary to

any

the

oree=conceived

above

increasing
increased
category,

its

principal

mainly

blocKk=diagrams.

c€an

imagery
also

for

used

This

(ERTS

«#ould

particularly

this

notions

will

target

the

does

but
more

only

nigner

oase

level

that

list

REGIS

may

cateqgory

canr

not

the

CA[L

suprort

and

ard
usec

performance

Similarly,

cartooning
and
so
1less than desired in
language

whicnh

flowe-charts

lack

complex

reoresents

and
presumaktly
handle the first

category.

for

comolexity

the

second

such

that

photo processing,
found
to
be

the

mean

restricted

relative

order
given
may adequately

images

not

protocol

assume

the
REGIS

abstract

data=plotting

necessary

real!)

complexity
in
cost.
Although

includes
for

(or

categories,

PEGIS

real=worla

forth)
these

out
cases

provided,

REGIS

FUNDAMENTALS...

Rev.

Paae

3.0
THE

BASE

LOGICAL

GRAPHIC

DEVICE

REGIS 1s used to define an image for
device
called
the REGIS Logical Graphic

this abstract device is a composite of a
devices.
Features unique to a specific
are

part

later

the

extended

sections.

REGIS

logical

concept,

terms of this abstract device,
device
is
transportable to a

an
abstract
grarhic
Device.
1In crinciple,

wide
type

range of
physical
of physical device

device

since

and

are

image

discusse

defined

with the exception that feature extensions are
1ignored
on
device
or
the
other or approximated in a ditferent wav on
device versus tne other,
It
1s
not
expected
that
any
specific
device
have the rarameters of the logical device,
rather eacn REGIS based physical device
maps
(transforms)
parameters

physical

given

terms

REGIS

locgical

device

Parameters

the

Attributes

viewing

The

general

wmodifving

nature

The

logical

device

its

phrase

one
but
the

specific

terms

of:

the

defining

viewina
image

area

the

viewing

are

drawn

range

parameters

attribute

with

the

type

The

allowed

feature

the

order

area

(REGIS by
ovorticns

which

the

received),

preference,
dependent

Aarea

points

“imolementation
or

defined

the attributes of the viewirg points
serial drawing process ..
the visible

allowed

parameter

viewing

process

of
the
image
instructions are

varies

the

one
one

parameters.

The

an image detined for one physical
different tyve of physical device

dependent”

value

will

that

attributes

will

has

physical

range

and

used

device

variance

defined

Device

viewing

semantic

for

refer

meaninag

with

which

oersonal

irplementation

detailea

later.

3.1
VIEWING

AREA

The

DEFINITIGN

REGIS

Logical

generallyv

rectangular

number

viewinge-point.

and

pounded

Usually,

four

viewing

homogeneous

point

structure

normally

corresponds

c¢hysical

the

image

ocutdoor

the

grid

same

Each

the

smallest

area

recause

the

that

Mathematically,

the

screen

area

will

may

the

aria

also

lines

screen
te

thouaht

union

can

all

area

aric.

area

w#ith

viewer
be

and

modifiea

preak

breaks

called

larae)

finite
lines

the

whicnh

possibly

crysical

seen

window

area

tnrat

rce

consists

invisible

the

viewinag

such

point

the

<¢an

the

©opoints

area

(althouah

that

scene,

viewing=

finite

viewina

sides

device,

manner

tre

"screen",

set

viewina-rcoints

REGIS

FUNDAMENTALS...

Rev,

Page

completely covers the viewing area.,
A viewing point may also be
referred to as a picture element or "pixel" for short (sometimes
referred to by the yet shorter nickname "pel').

has

“hen

the

1its

"normal"

screen

rotated

such

relative

to these

then

manner

four

the

that

sides also

four

the

edges

image

the
rectangular screen are called the left, right,
top
and
bottom
edges
in
accordance with the normal meaning of these words and
the terms horizontal and vertical are used
to
refer
to
pixel

positions

orientation,

in accordance with

the normal meaning of these words, The position of
each
pixel
on
the
screen is uniguely identified by the combination of two
numbers wnich refer to the horizontal (or X)
position
and
the
vertical
(or
Y)
position
of the pixel.
Using this the pixel
(viewing=point) VP(X,Y) refers
to
the
horizontal
value
denoted by the number
denoted

range
which
of

tne

Using
of
are

number

taken

non-nedgative

and

tnese

and

point

at
the
vertical value

REGIS instructions,
values
o©0f
X and Y

generalitv,

viewing
X and at

the user may define the
vossibple
by identifving the numeric values
at

the

four

parameters

directly

define

edges,

may

the

without
assumed

following

1loss
to

screen

area

parameters:

SYT

value

SiB

Yalue

the

Y=-position

screen

the

oottom

the

Y=position at

the

top

screen

area

SXL

Yalue

the

left

SXR

= Value

X at

the

right

edge

edgqge

Assuming for tne moment that these parameters are all of integer
value,
these
parameters
1indirectly define trhe total numrber c¢f
horizontal ana vertical positions to be used as follows:
aos(SXR=SXL)+1
the number of norizontal

=
=

SXN

screen

positions
SY!!

=
=

30s(SYT=-SYB)+1
the number 0of vertical
screen positions

STN

SYN

SXN

the

total

numoer

positions

These parameters
graphic
device

referring
quality

unique
of

can now be
used
to
‘"resolution"
(here

guantitv

tne

(number

incividual

information
pixels)

screen

oixels)

gefine
three
used
in the

capability
follows:

ranges
context

and

not

ot
of

tre

REGIS FUNDAMENTALS... Rev. 1
1.

LOW

RESOLUTION

MIN(SXN,SYN)

MEDIUM

256
3.

Page 24

256

RESGCLUTION

<= MINM(SXN,SYN)

1024

HIGH RESOLUTION
MIN(SXN,SYN) > 1024

REGIS differentiates between the low/medium class of devices and
the high resolution devices in a special way.
B8asically, screen
positions for low resolution devices and definable
entirely
by
using integer numbers or the whole parts of generally fractional
numbers.
The additional resolution of higah
resolution
devices

is
required
to
be accessed by fractional rcarts of the X and Y
values.
In this manner, the simpler low resolution devices
mav
easily "acoroximate" the positions on high resolution devices bty
simply taking the integer parts of all numbers and similarly,
a
high
resolution device may depict an image with better fidelity
by making use of the fractional pvarts
of
the
values,
Mecdium

resolution devices
addéition

the

may use

4hole

some part of

parts

the

fractional values

implementation

aependent

basis.

have

governing

now

the

established

degree

reasonable

fidelity

frame=work

fcr

rules

of representing a graphic

image:

LOWY RESOLUTIOWN CEVICES are given the greatest
degree of fidelity of representation

MEDIUM

RESOLUTION

possiole
"jagged

HIGH
with

ideal,

eages"

should attempt

cet

the

that

wav

as close

recognizina that there still may be

occasionally

RESOLUTION cdevices are exrected to represent
tne maximum possible degree of fiagelity.

Note

real
most
size

devices

the

lee

the

REGIS

BASE

logical

device

the

ignorant

image

thre

physical
size
of
a pixel, consistent with the fact that
low resolution graonic devices nhave no
controllable
pixel
(as in tne case of raster CRT, stroke CRT, and storacge CkI

devices).

physical

Qther

devices

opixel

sizes

determination

determined

the

above

must

therefore

define

default

values

from the given data in conjunction with a

resolution

tnhe

oricinal

device

paramters.

‘iote that the parameter SXR is not necess rily greater trar
SXLL
and
similariv, SYT is not necessarily larcer than SY®.
To
define the ReGIS instructions in terms of the logical device, it
#ill

necessary

bte

arvle

ldentify

the

oixels

which

are

above, oelow, to tne left and to the right of a given pixel,
1in
terms
of
the user supoliec screen coordinate cefinition.
This
is accomplisned by the X,Y screen
increments
SXIH#C
ana
SYI«C
#nhich

are

defined

SXIMNC

tollows:

SGV(SXR,3XL)

REGIS

FUNDAMENTALS...

Rev,.

Page

SYINC = SGN(SYB,SYT)
where

SGN(

)

the

signum

VP (X+SXINC,Y)
VP (X=SXINC,Y)

function.

the

right

the

left

¢:ZVP(X,¥+SYINC)

below

VP(X,Y=SYINC)

VP(X,Y)

above

VP(X,Y)

this

convention:

VP(X,Y)

3.2
VIEWING

POINT

ATTRIBUTES

Each viewing point generally
has
a
forearound
intensity
attrioute,
a
background
intensity attribute and a foregrouncéebackground
selector
attricute
as
defined
in
the
following

paragraphs.

Each pixel nas a background "intensity"
BI(X,Y),
The
semantic
meaning
of
the
implementation dependent in
the
sense
fo
photometric
measurement
units.,
Intensity

device

propercty
value

defined

simply

viewing

sevaraole

peing

poinrt

such

from

another

some

that

value
called
word
intensity
psychoohysical

in the
wvisually

mixel

pixel

have

the

1is
and

RASE

logical
<discernible

one

intensity

different

naving

intensity
valuye,
The
BASE
REGIS
LOGICAL
DEVICE
IS
EOTH
COLOR=-BLIND AND BINARY in
terms
of
intensity
attributes,
so
without
1loss
of
generalitv,
we
may assume that the possible
values

BI(X,Y)

The

pixel
Base
of

are

either

"off"

"on".

foreground

intensity
attribute
associateaq
with
tre
X,Y is denoted oy FI(X,Y) ana similarly in the
device may have values of "on" or
"off",
Eecause

position

logical
the

bpinary

quantities

are

nature

redundant,

since
tney
will
logical device,

the

Dbase

but

are

needed

device,

included

the

here

for

definition

anrd

completeness

the

extendec

tacn viewing point
has
a
foreground-=cacxground
function denoted by F8S({X,¥Y,t) which has a binary
value

selector

generally

values
alsoc

function

FB8S

denoted

will

the

selection
also
funticn for each
defined

value

seen,

FBS(X,Y)

impsosed

'In

B8I(X,Y)

for

all

hnas

time,

taken

binary

denoted
VB(X,Y)

foreground

o¥
to

uniform

"F"

"1")

(for
and

J#hich

generalitv,

torearound
"g"

(for

is
tre

selection
background

tne
cinary
wvalue
"0"),
The FRS
used to select whether the currently
currently defined btackarouna attribute

base

"F"

off

(X,Y).

value

loss

the

#ithout

logical

for

cevice,

all

(X,Y)

Then

the

set

("1")

will

bacgaround

and

ajl

we
the

VE(X,Y)

visually

intensitv,

may
valuye

take
of

tre

FI(X,Y)

for

ciscernible

«wricth
a8s

REGIS FUNDAMENTALS...

Rev,

Page 26

3.3

GENERAL

DRAWING

PROCESS

The generation of

image

the

1logical

device

(as

image

may

distinguished
£from
the
definition
of
the image) consists of
execyting a sequence of instructions which modify the FBS values
for
a selected subset of X,Y values.
Note that the sequence of
instruction execution is important in REGIS whereas the order of
image
definition
constructs in a higher level agraohic language
may not be important.
The general
process
of
generating
a
REGIS logical image is as follows:

STEP 1:

An
be

Define the viewing area parameters.
area

the viewing

STEP

Erase

STEP

ldentify a sequence of X,Y
change the FBS for each of

image may bpe

drawn

steps

MGCDIFIED by

repeating

from

positions ang
tnese pixels,.

repeating step

step

In terms of the different
REGIS
are accomplished as follows:

A new

1instructions,

the

atove

The SCREEN instruction is used to define the viewing area

parameters,
screen

set

the

background

The WRITING attributes
foreground attriobutes,

The

attritutes

and

erase

the

image,

POSITION

instruction is used to set the
particularly line drawing vatterns.

instruction

used

position to E@;begin sriting points.

select
an X,Y

pixel

The VECTOR, CURVE, and TEXT instructions are used to
modify a seguence of FBS values for pixels from the current

X,Y position ana generally
position

tne

screen,

ending up

a different

REGIS

FUNDAMENTALS...

Rev,

Paace

4,0
REGIS

GEMERAL

SYNTAX

This section discusses the general
REGIS.
This discussion
applies
not

instructions

general

discussed

framework

general

grammar.

transportapility
general

grammar

for

the

syntax

and

only

semantics
the

BASE

section

out

also

provides

REGIS

way

extending

That

is,

REGIS

can

support

for

any

extension

1long

the

REGIS
.

the

REGIS

purpose

conforms

rules.

the

Since REGIS is meant to be used in
conjunction
with
high
languages, extensions to REGIS should not include the mcre
tradicional "program structure"
features
such
as
conditional
level

control

and

programming

computations

REGIS

{tself

language,

not

4.1
Alphabet
REGIS
alphabets

1s based princioally on
2yt
for
the
purpose

restricted

and

EBCDIC

therefore

that

case

letters

dypper

case

Uevices

convert

which

oarenthesis
option

The

bracket

well,

0)
REGIS

°*°"

conferm

addition,

upper

have

case

"(" and ")"
outside of quoted

"(["

outsice

always

guotea

and
o0f

";"

s
BCD

alchabet

=
this

the

and

comclete.,

alpnapet

but

are

rance

treateg
a

aquoted

case

surcport
strinas.

should

alphabet

the

may

reserved

strings.

reservea

i{s,

terminate

string

REGIS

"1" should
te
quoted strings.

That
are

common

usec

quoted

characters

character

lower

parameters

terminate

may

not

separator.

#ill

ASCII-128

following

wnich

characters

semi=-cclon

...

+
to

the

arguments

instruction

are

The

outside

sequences

instruction
cnaracter

and

gytilization

characters:

letters

lower

for

not

ASCII-=96
maximumr

aoply:

The

extensions

possiple,

vposition
4.

following

0,1, cee,s9

string.

the

Lower

also

systems

A,B,eees?

alphabet

those

conventions

only

consists

hooed

much

use

tre
o
characte

reserveg

fer

occurrence

instruction

The

"“;"

construction,

for

use

3as

tnhe

":*"

whether

tre

cnaracter

coes

REGIS

FUNDAMENTALS...

The

"at"
strings

Rev.

Page

character "g" is reserved
and may not be used iIn any

for
use
by
other context

macrograrch

outside
a quoted string.,
Within quoted strings the "@" character
just
another
printing
character
..
that is, there is
ability to expand macrograohs within quoted strings,.

is
ro

The

blank

cnaracter

quoted
strings.
characters are not
constant
strings.
delimit successive
7.

The

comma

generally

1ignored

outside

The
exception
¢to
this
1is
that
blank
allowed
within
the
extent
of
numeric
Thus, the blank character can be used to
numeric parameters.

character

separator
and
characters are
two
adjoining

","

serves

generally

arqgument

1s
generally
1ignored
unless the adjoining
otherwise indistiguisnable as in the case
of
digit sequences which refer to two different

numpers.,

ASClI

control

and

characters
device

and

conrtrol

in REGIS and in concepr can
affecting the interpretation

similar

characters

communications
are

te
insertea
preocess.

1line

gererally

ignored

arywhere

without

4,2

General Gfammar
Figure
4
notation
which

illustrates
and
summarizes
will
be
used
to descrice
This
meta-notation
is
the

instructions.
extension

meta-notation

the

Backus

originally

HNeaur

ferm

developecd

for

use

the
meta=languace
the syntax of REGIS
cemmonly
Backus

emploved

dNormal

aefininag

Fornm

the

ALGCL

language,

Figure
S5
summarizes
the
following
paraaraphs
state
1in
succinctly
1.

REGIS

defines
image

sequence
separated
does
not
ignored,
2.

REGIS
general
qrammar.
words
what
this
fiqure
mathematical terms,

definition

o¢f

arpitrary

1lercgth

o0f
intsructions
rcossibly
(but
no
necessarilvy)
by the semi-colon character.
Any character
«hich
ovegin
an
instruction (a <letter> character ) is
.

A REGIS instruction consists of a KEY-LETTER tollowed
pov
a
parameter
list.
REGIS is therefore limitec to havincg onlvy
26 different types of instructions.
Since
there
are
only

six
keywletters
used
significant restriction
extension,
3.

consists

The
more

1in
and

the
KEGIS
BASE
this
1leaves
consiceraole

instruction
parameter
list
of
four
basic
tyces

number

aroitrary
instructions

order
anada

consists
of
parameters

syntacticallyv.
instruction

1is not a
room
tor

arbitrary
in an

arrandaed

Semrantically,

rcarameters

are

assumed

all
to

pve

REGIS

FUNDOAMENTALS...

executed

those

seqguence

sequence

text

("lefteto=right")

and

string

and

characters

guote

character,

* character.
included
1in
single

strina

the

bracket

begins

with

apostrophe

single

are

quote

the

string

character

delimited

not

part

text

begins

with

The

the

text

string

the

full

refers

the

string

character
quote

character
can
be
doubled by simply using

being

quote

the

string

the

string

‘"?

refers

the

string

“*"

refers

the

string

‘OEF’

resulting

are

two

string

consecutive

structure

For

example:

A’"B
parameters.
cccurr.,

string carameters,

is:

and

included

‘

the

delimiter

a‘cC

string

refers

can

character,

"A"

refers

character

similarly a
string
terminated #ith the

REGIS instructions may have multiple string
the
<this
case
the following ambiguity may

and

apostrophe

character

argument.

included

which

without

single

"A°""B"

“ABC’

characters

the

w#ith

themselves

1In
a string

**#**

the

reception

argument,

by the ° character and
the " character is not
this
way
the,
the
"

‘a’’C’®

the

doubled.
The full guote character °*"°* may also
string delimiter in the same way as the
single

not terminated
which begins with

the

which

apostrophe

similarly

position

treated

string.

then
it
1is
te used as a

enclosed

X/Y

ends

apostrophe

parameters,

characters

"""

Page

characters

refers

character

order

instructions

generally

the

Rev.

tnen

‘ABC*‘DEF"
wnich

#i{1l

This

treated

ambiquity

may

consecutive

string

may

arise

particularly

used

Digit

supply

the

characters

arguments

where

REGIS

paramters
in

string

the

by
the

single

the

comrma

context

efither

argument

Sequences

syntax

characters
"("

each

instruction

enclosed

and

")"

ovotion

1is

including

£or

readabilitv,

separated

options
comma

ABC’'CEF.
possible

character.

that

numbers
a

This

macregranns

are

sequences

rerfer

the

within

same

character

the

instruction

oparameters
(also

digit

argument,

cnaraccters

string

separating

vcarameters.

represent
each

avoided

the

called

characters

syntax

the

four

rarenthesis
cotions.

not

Tre

PEGIS

basic

types.

sut=instructions)

but

the

mav

semiccleon

REGIS FUNDAMENTALS
... Rev.
character

Figure 5 also
BASE

Page

wnich would terminate

summarizes

instructions.

the

instruction.

semantic meaning of

the

six

KEGIS

REGIS

FUNDAMENTALS...

Figure

The syntax
Backus
Normal
following:
<

Rev,

REGIS

Form

the

gquantity

ASCII

the

Means

means

that

py")

either

that

number

from

the

syntax

terms

the
of

the

enclosed

A<KB>

. CTr.{B}

<B>

the

name
has

syntax

string
or

characters.

that

<A>

character

may

repeated

be
is

made

forms

the

character

left

which

remresentation

equation:

defined

("can

beginning

definatle

defined

(.cr.)

themselves,

cnaracters

characters

left

forms

single

svntax

<A>

the

string

selection

printing

represent

variable

string

o0f

the

string

the

string

following

==>

variabcle

one

times,

enclosed

wise

-w>

carriage=-return

"B"

the

characters

tne

the

extended

variables

rignht

any

other

<AD>

the

Enclose

example,

variaole

syntactic

Select one Of the alternative
or right of this symbol

All

followed

be replaced
characters)

that

other

For

in
terms
of
the
metae-syntax,
summarized

name

defined

‘

means

}

NOTATION

(BNF)

defined

{

Page

META-LANGUAGE

Enclose

and

string

followed

with

the

rerlaced

"A"

and
syntax

starting

any

witpr

numrber

REGIS FUNDAMENTALS...

Figure
<REGIS>

==>

;

-=>

<any

==>

<PAR=LIST>

SYNTAX

<REGIS>

<KEY>

<REGIS>

<PAR-LIST>

‘<text>

<PAR-LIST>

==>

"<text2>

<PAR-LIST>

w=e>

(<KCPTION=LIST>

w=>

[<x=y

-=>

<digit>

‘*

-=>

<any

==>

Page

==>

GEWERAL

character>
<==>

KOPTINN=LIST>

<text>

<REGIS>

==>

<KEY>

Rev,

<PAR~-LIST>

arqument>)]

<PAR-LIST>

<PAR=LIST>

==>

<KEYD>

==>

<PAR=LIST>

<CPTION=LIST>

<OPTION=LIST>

other

character>

<text>

other

character>

<text>

"
<any

REGIS

FUNDAMENTALS...

Rev.

Page

4.3
MACROGRAPH

STRINGS

Macrograph strings provide the
arility
for
define
a
commonly
used
character
seaquence

temporarily

anyplace

1in

the

graphics

the

allow

user

macrograph

strings

complete

instructions

several

used

not

the

then

refer

- sub=-picture
Rather,

reducing

collect

execute

image

structure

macrographs

veing

referred
reduction

to
of

reducing
improving

the
the

this

together

these

string

Although
several

instructions

general
instructions,

causes

the

SIGGRAPH
are

CORE
segment
syntactic
mechanism

number
o0f
characters
tnat
have
to
be
communications interface.
For example,
1f
drawn is a sheet of music, each of the different
the

defined as

a macroqgraph string and

by
its
name
resulting
communications
overhead

readability of
readability).

Macrograch

REGIS

Oor

strings

the

over

‘types of notes could be

strincs

the

conform

image

definition

grammar

oossibly

teo

tre

That is, in the process of varsing REGIS
detection of
a
macrograph
string
reference

the

characters

previously

defined

for

that

the

general case a macrograch string may be
instruction (such as a position argument)

(such

(and

built

grammar,

substituted

thern

in
as
much as a 5 to 1
without
substantially

piece

execution,

stored

during the generation of a single image or
to
be
generation of each of several separate irages, it is
intent of macrograph strings to serve
as
the
commonly

transmitted

user
be

tne

structure.

the

and

instruction

times

employed

for

device

sequence

the
to

for

the

argument

string

reference

macroararh

characters.

Thus,

just

argument

may

even

suc~instruction).

All operations relating to macrographs are initiated ny the
*at"TM
character
‘“"g",.
The
syntax
of macrocaraph orerations is
defined in figure S and descrined in words in the tollowin
g:
l.

There

are

defined,

letter

(lower

ourpose

The

("at"

macrograon

string
ce

case

be
if

A macrograon

converted

cleared

interoreted

defined
they

are

string

urver

The

must

which

identified

bty

case

can
a

single

for

tne

identification).

period).

consist

strings

are

altogether

string

strings

string

may

Cleared

peing

followed

defined

Macrograon

strings

macrograph

macrograoh

macrograph

"a,"
is

macrograph

gach

the

meaning

characters
clearea

and

used.

not

defined

chraracter

orveration
(

that

tne

the

emoty

before

any

tacrograsns

sequence

Clearing

string

string).

macrograch

not

have

used.

the

seguence:

2:<letter><STRING>Q;
#nere
any

sequence

seguence
the

refers

cof

"“a:"

sequence

any

characters

called

the

"ags"

alchabet

not

character,

containinpc

strinc
called

"@;"

definition
the

“e:",

qre

initisatar

ara

strinrg

aqefirition

REGIS

FUNDAMENTALS...

Rev,

Page

terminator.

A macrograph string

referred

by the

sequence

a<letter>
where <letter> is one the names given
macrograph.,
This sequence may appear
of REGIS istructions.

a
previously
anyplace in a

defined
sequence

The following notes refer to conventions toc be
applied
to
achieve
maximum
transportability
of
images
which
use
this
capability:

A macrograoh
another

string

macrograph

can

string

not
(no

contain

the

"conditional"

definicion

defirnition).

A macrogrash string definition may refer to otner macrograph
strings
iIn
a nested manner.
For maximum transcortability,
this capapllity srould not be used for more than one
level.
A
macrograph
string
mav
not
refer
to
itself
in
its
definition
either
directly
or
1indirectly
(no
recursive
string definition capapnilitvy.

If a macrograph is
the 0ld definition
0la

definition

w~macrograph

defined which already
is revlaced by the new

1Is
defined,
tnen
definition and the

lost.,

string

may

o0of

any

1lenrngtn

(including

cnaracters
at
all
..
the
null
string) cut for maximum
transportapility, the sum of the character lengtns used
for
all
macrographs
snould
not
exceed 2000 characters.
Some
systems may have difficulty transmitting character sequences
longer tnan 80 characters.

4.4

POSL{TION

0f
(pv)

ARGUMENTS

REGIS provides two
drawing positions:
relative

movement,

syntactic

(1)

X/Y

structures for the
definiticn
ccordinates and (2) pixel=-vextoer

Pixelevectors

corresponc

0ld
(but still very useful) "chaineencoaing"
still used today to arive
many
incremental

The

X/Y coorcinate

defining

positions

structure

using

numpers

two

the

somewhat

ronghlvy

technigue
»oplotting

tradition

separateac

the

which is
Zevices,

system of
comra

(or

space) cnaracter with a new twist which allows coth absolute anc
relative coordinates to
te
svntactically
distincuisnaple
arnc
thus elininating the neec [0 nave sevarate relative ara atcsclute
instructions or options.

REGIS

FUNDAMENTALS...

4,4,1

Pilxel

Rev.

Fage

vVectors

Syntactically, a pixel=-vector is
character
1in the range 0 to 7.
Each

one

the

eight

position.,
number

around

By
a

crixel

convention,

refers

convention

the

circle

neighbors

©v number

pixel

summarized

denoted by a single
digit
of these nurbers refers to

and

The

notes

cnaracter

the

counter-clockwise

the

following

the

right

aoply

refers

folloWing

3|2}

The

relative

the

current

rignht,

and

fortnr

direction.

This

ciacram:

% | O

S|e|]

use

pixelevectcrs:

sequence:

0228

refers

number

two-=nundred

nNote
no

The

that

size

the

atter

base

one

OCepending

error

and

relative

default

occasionally

thus

attritutes
pixel

(linear

the

pesitioning

arc

the

o0f

unit

size

(cefined

ir
multiplicative

the

pixel

another

vectors
a

device

diagonal

directiors.

the

pixel

size

definec

tre

exact

consitior

unit

operatior,
pv’s

cositicning

absolute

the

overationr

instruction

versus

setup

seguence
ov

not

vector.

measure)

direction

granularity
a

setur

modifiatle

unit

coordinate

executinag

particularvy

the

screen
and

and

lengtn

1In

basis

tne

vectors

onlv

coorainate

writing

the

deoendent

pixel

allow

vector

screen

section)

vary

four

twWwenty-six.

vectors

pixel

the

ohysical

may

and

position.

factor

TIne

pixel

Aaultiple

sequence

aosolute

defined
the

subject

seacuences

opositionina,

should

rounacff
ke

hroker

REGIS

FUNDAMENTALS
... RV,

4.4.2

REGIS

PARAMETER

==>

of a position
follows:

==>

<ypart>

==>

,<coordinate>

-=>

(nil)

meaning

=«>

<n>

wad>

+<{N>

-=>

(nil)

forms

argument

£&gach

coordinate

plus

coordinate

part

minus

consists

sign

vart

("+"

not

ot
or

1If

is,

the

coordinate

that

part

the

amount

x-gosition part
which ray te

¢toth

number

prossitly

preceeded

sign

character,”

"e"),

preceeded by

then
that
argument
{s an abcsolute coorainate
the value 0of that vart is cnanced
to
be
this

indevendent

for

argument

follows:

generally consists
part,
either
or

and
a
y=-position
missing.

parameter

these

position

([<Kxpart><ypart>]

The

Page

POSITIONING

The general syntax
instruction is as
<PA>

o0ld

part

changed

coordinate
given

value

part

the

that

preceeded

relative

number

coordinate,.
a

the

sign

its

increased
in

meaning that
new
numper

character,

currernt

aecreasecd

direction

then

value.

That

inaicated

the

sign,

Note
basis

that one
while

absolute
o.

then

Examples

coordinate
the
other

part can be
coordinate

on
1is

relative
on an

changed

odasis,

coordinate

has

that

part

change
part

part
coordinate

usinag

position

nil
definition
(no
is left unchanageaq.

arguments

are

agiver

<characters)

the

section.

4,4,3

high

Position

REGIS allows a form
level languages as

drawving
can

several
restored

This
all,

Blocks

positions.
saved

feature
1t

This

iIintervening
to

1its

of block structure (berrowed
ALGCL, ?2L1 and PASCAL) to oe

o0ld

means

"begin"

oposition

1in

many

current

<chances

positiocn

impcocrtant

reduces

that

operatior

REGIS
cases

for
tne

and

the
"end"

two
number

from
sucth
arvlied tc

draving

later

positien
of

block

reascns.
of

positior

after

ctossiblv

can

overatior.

First

crnaracters

c¢t

whichn

REGIS

have

FUNDAMENTALS...

pbe

graphics
curve

sent

device

sections

sequence

the

and

Page

remote

identified

option

the

curve

Only

characters
drawing

structures

The

"B"

tegin

and

1instruction

following

one

mechanism

"end"

reference

saved

The

these

notes

records

"begin"

This

block

maximum

and

"“E"
to

allows

the

polvaon

and

from
end

which

avply

block

vector

Jjust

points

the

wuses

opticn

the

block

a
are

block

structure

operation

should

structure

may

beqin

points.
Thus,
an
can cause a position
position instruction to be

instruction
in

avcided

for

nested

transportability

only

clarityvy

but
1

for

1level

should

be used (only one level {is needed
benefits of block structuring).

tne

closed

returned,
2.

Secondly,

identify

arcs.

positioning:

point.

syntactically
or

arguments

The

distinguish

vectors

structure,

Rev,

thre
of

possible.
purocose

tlock

structure

achieve

mest

4.5

EXTENSIBILITY
The
REGIS

following

taxe

W#hen

new

Avoid

REGIS

using a
as

device

syntax

standard

for

whicnh

REGILS

Syntactic

extension

outlined

those

device

snould

arauments

SKip

allow

wnich

over

<SKIPS>

of
are

implement

which

instructions

are

==>

has

all
used

its

implement

the

dlready

tbteen

not

intended

tne

ohilosorhy

ensurea

range

section.

recuiring

tpe

arquments

anc

irstruction

forms

povarticular,

eacth

not.

the

following
arguments
which

oracket
]

not

which

teyond
in

transportability

implementation

whether

does

extension,

Do not try to extend REGIS

elements

for
extendinag
characteristics:

type should only oce added to REGIS if
the
can not be performed by a sequence of existing
instructions and the designer
can
ensvre
a
wminimal
of
information
content
when
the new instruction is

applicapility

complete

guidelines

soecific

instruction

by a
instruction.

general

device

a new feature should be
added
to existing instructions.,

options

loss
ignored

dsed

give
of

operation

REGIS

notes

advantage

possiple,

adding

GUIDELINES

iTplemented

parametfer:

*“skioping"

syntactic

are

usec

not

iarored:

REGIS

FUNDAMENTALS...

=«>

SKip

over

<SKIPQ>

text

Skip

*
<any=-other>

Having

aid

device

for

1in
might

sequence:

)
<letter><SKIFI><SKIPP>

-=>

<SKIPP>

entire

instruction:

==>

[<KSKIPB><SKIPI>

==>

(KSKIPP><SKIPI>

-=>

‘<SKIPQ>LKSKIPI>

==>

"<SKIPQO2><SKIPI>

==>

these

«#hich

skipping

varianle
semantic

detecting

errors

choose

set

implementation,

variaples

for

each

meaning

ararchic

flag

which

to
be
snown
Anvtime
one
o0f
accessed,
This
4would
also
be
particular
4graphic
definition
REGIS

-=>

the avppropriate

arguments

<SKIFQ>

*
<any=other>

option

implemented

invoke

<SKIPB>

==>

over

string:

==>

over

<SKIPI>

Page

-=>

<SKIPP>

<any=-other>

Skip

Rev.

device

the

has

Eteen
an

then

imolemented.

definition
causes

would

instructions
seauences,

error

messace

these
skirpina
elements
were
heloful
in
ensuring
that
a
meets
some predefinea level of

REGIS

FUNDAMENTALS...

Rev,

Page

5.0
BASE

REGIS

This
BASE

INSTRUCTIONS

section

REGIS

syntactic
numeric

details

the

1instructions,

elements

parameters

given

notation.

determining

the

implement

interpretation

and
6

instructions.
to

sclentific

the

syntax
Figure

The

following

fildelity

extract

the

integer

number

of
the

Note

that

integer,

rules

should

which

different

numeric

formats:

portions

the

six

primitive
-

REGIS

flocating

Low resolution devices are assumed
quantities
only.
However,
1low
notation

semantics
summrarizes

allows

point

used

devices

and

in
must

to
use
integer
numeric
resolution
devices
must

floating

point

and

scientic

constants.

2.,

¥edium resolution devices at least reduce numeric guantities
to
1integer
form
put
may
also
use
some
oortion of thre
increased resolution provided bv floating point rumbers.

High

resolution

For
semantics

devices

orovided

are

expected

floating

reference purposes, figure
for the pase instructions

reference,

coint

use

the

entire

numbers.

7 summarizes the syntax
and
in a form suitaocle for qguick

REGIS

FUNDAMENTALS...

Flgure
SYNTAX
ITEM
<char>

|
I

REGIS

Rev,

BASIC

Page

SYNTAX

SINTAX
VARIATION

|
|

ELEMENTS

MEANING

Any

ASCII

orinting

<letter>|

Any

ASCII

letter

character

(lower

case

conversion)

--'-----'------------------_--l---------------‘-------------------------------

<digit>i

Any

the

characters

--"----"--------h-------‘---‘----------------------------------‘-----------_

<pvVv>

Pixel

<bit>

The

omaceaew | ----——-—-—--------—--] D D G

<n>

|
i

<ni>

<ng¢>

<ne>

‘G’

ané

‘1’
e

CONSTANT

Integer

constant

<digit>{<digit>}
Fixed

point

<ni>.{(<digic>}

{
ang>

characters

0,1,2,3,4,5,6,7

D TS D D G D WD TS WD T W P GO D AP WD P UD WD P WP O b SO G N WP G D P e A GE P O AN A O W S

NUMERIC

|
I
i

;

vector characters

rloating coint numrter
<nE&>E{+i1=-}<ni>

Angle

0<=

<n>

number

argument

=360

.-------'---------------Q-----'--------------—-------‘------------Cfi---------.

<pcnt>

<nd>

. such

PERCENTAGE

that

0<=

<n>

ARGUMENT

100

.-----C-‘-----“-----C--------‘---'-------------------------------------QOOQ--

<pa>

<pax>

POSITICN

ARGUMENT

X-position

part

]

<nii>

{

<n>

set

+<n>

increase

<n>

decrease

bty

<n>

{
{

-<n>

X=position
X

change

acsolute

<n>

Y-position part
no Y=position change

set

{
|

s +<N>
s =<0

increase
decrease

absolute

v by
vy by

<n>

<n>
<n>

---‘-‘--l-‘------------‘----'-'------------------O---------------------—-----

<aa>

|
|

ABSGLUTE

same

<pa>

exceot

only

X,Y

absolute

ARGIMENTS

and

arauments

.-------‘---------—_----------‘--------------------Q'-----‘---------C--------.

<ra>

{

RELATIVE

same

<pa>

except

only

X,Y

relative

ARGUMENTS

and

arguments

REGIS

FUNDAMENTALS...

Figure

7.,

AlLINST.
i KEY

IPARAM=| ETER

|
|

Xt
Xt

|
[

REGIS

BASE

Rev,

Page -1

INSTRUCTIONS

PARAMETER
VALUES

|
|

)

|
}
i

|
{
i

S[(KLT>] [<RB>}
T(S<n>)
A {<aad>]

MEANING

SCREEN INSTRUCTION
Screen OUptions
erase screen
define screen coordinates
adjust standard text size
adjust pixel vector size

" ------l -‘--‘--’ "--------------' ---‘-------'------------------

------------------

X1
X}
Xi

|
I
{

{

|
X4
X1

|
i
I

P2 to P9
P<bit>,..

)
PO

full

POSITION

[(<pad>]

<digit>

(

Set

{

bcunded

<digie>

(

Draw

I
{

begin

end

)

| crcnccn |

Xt
Xl
X1

I
i
!

{

position

<pad>

seaquence

crrncnrcae | chccr

vector
secuyence

e rcr e rrcrcra

CURVE

(<pa>]
(
)

btounded

vector

T e e rc e

A<ang>

draw

circular

start

curve

]

Eeqgin

bounded

curve

end

curve

seauyence

|
X1

‘<text>’

“<text2>"

)

Draw

<text>

<text?2>

|
|
i

i<letter>

[

<ga>

secuence

it T T T

string

text

standard

strina
ortions

text

size

multiole

T O

MACRCGRAPH STRIMNG
Initialize (clear) macrograph strings
Begin detinition ot string <letter>
End

INSTRUCTION

Craw
set
T T

.- -

sequence

S<n>
L D

Graohic

i
e

TEXT

I«

Xi
X\
X

<ga>

arc

{
|

c e e

Draw circle (arc) throucn <pa>
Curve options
draw circle (arc) centered on

INSTRUCTI1GN

)

cursor

seauence

X}
Xt

cursor

senuvence

e Rtk

current

Draw pixel vector
Vvector options

INSTRUCTION
vector from current

{
| memcn

INSTRUCTION

cursor

vosition

VECTOR

(<pa>d>]

CURSUGR

current

end

{

pattern

vector change
Position options

)

writing

Pixel

line

predefined line patterns
user defined 1line pattern
Set pixel vector multiplier

(<aa>]

WRITING ATTRIBUTES IuSTRUCTION
writing Ootions
’
invisible line writing pattern

macrograch string
Sutstitute macrograrn

cdefinition
string

REGIS

FUNDAMENTALS...

Rev,

Page

S.1

The

SCREEN

Instruction

PURPOSE

)
The screen instruction, key-=letter "S", is used
to
control
screen coordinate parameters and attributes which affect the
entire viewing
area.
In
the
REGIS
BASE
tnhis
Iincludes
clearing
the
screen area, setting the coordinate system to
pe
used
and
making
adjustments
to
device
sveciftic
parameters,

SYNTAX
<REGIS>

==>

<SQOPS>

The

forms

skKip

==>

[<KSKIPB>

==>

‘<SKIPQ>

==>

"<SKIPQO2><SCREEN>

~=>

<digit>

==>

(<SCPS>

==>

k£

-=>

S{<pa>] (<pa>]

<SUPS>

w=>

T(S<Nn>)

<S0PS>

~=>

Ww{<aa>]

<sSuPs>

ww>

<SOPS>

~=>

)

-=>

<any=other>

<SKIPB>

and
(ignore)

over

<S(PS>

<SKIFI>

<SKIPC>
bracket

are

<SOPS>

syntactic

states

quoted

string

and

resvectively,
The form <SKIPI> is a syntactic
skip over an entire instruction, inclucding all

S.1.1

Screen

letter

"E"

prevaration
"erase"

creating

0of

erase
1s

S(E)

wused

drawing

device

The

roughly

new

dependent

homogeneous

screen

image,
but

visual

erase

initialize

The

generally

image,

For

the

state usec to
parameters.

odtion,

ocvtion

viewing

precise
has

used
to
arauments

the

example,

area

meaning

connotation

the

in
of
of

sequence

characters:

S(E)

will cause (or reguest to be caused) a new sheet of paper
loaded
into a flat-ted plotter and will cause the entire
to have no visiple structure (all olack, all wnite
etc,)
raster display device,
For devices which
noparameters
and
attriputes
(excect

all

attrioutes
the

themselves)

execution

0of

the

should

screen

take

erase

have REGIS
possicly

their

tunction.

aefault

to
be
screer
ir
a

extensions,
for
screer
values

uron

REGIS

FUNDAMENTALS...

S.1.,2

Screen

coordinate
sequence

#hich
may

Pev,

Coordinate

definition

which

are

definition

the

used

defaults

for

corner

user

the

viewing

defined

viewing

this

screen

area

parameter

coordinates

will

coordinates

the

most

1In

this

unary

the

operators,

coordinate

arguments.

gives

the

and

the

lower

second

riant

accommodate

device

position

device

rectangle

settinas,

set

that

the

and

thus

ranges

scecific

vositionina.

case,

screen

implementaticn

arguments.
upper=left

normally

necessary

transforming

define

The

ootion has
two
position
defined coordinates of the

functions

coordinate

scaling

corner

in
the
“Logical Device"
sufficient
for
the
device
to

scaling

often.,

mandatory

described

1information

appropriate

S(S{

position

coordinates

area.

user

The screen definition
first
gives the user

The

Page

option

allows

define

1is

assumed

the

actual

the

reducing

wided

arplication

device

set

can

the

set

range

that

the

physical

1is

overhead

the

section,

determine

transforration

thre

use

the

that

functions
recuired

to
in

arguments.,

EXAMPLES

$(s{0,01(383,239])

Sets

the

upper

"oriain®

left

anproximately

standard

S(s5(0,5111(511,0])

point

corner

with

to
a

equivalent

broadcast

the

range

Tv.

Sets the origin coint to
lower left corner with a

ecquivalent

doproximately
redium

resolution

raster

terminal

the

range
a

grapnics

disclav.

S(5{1,1](1000,00,500.001)
-

Note

that

the

number

Sets

the

hligh

resolution

opixels

coordinate

ranges

plotring

actually

¢or

device.

accessible

tre

integral
opart
of
the
screen
parameters.
Accessirclity to a
larger numoer of pixels than can be addressed in this manner for
hign
resolution devices mav ose accomolisned by using the S(%
..
) option descrioed rtelow,
FIDELITY
1.

Low

IMPLEMENTATICOw

resolution

devices

have

the

dJgreatest

tlexicility

implementing tne coordiante transformation feature, but
implement some form of transtormation.
The
sirrplest

“ould

the

round=off

nearest

coordinate

the

positioning

carcability.

The

simple

operations.

Using

snift

taree-fourtns

the

multiole

+edium
tnhe

tne

resolution

transformation
£

viewirg

devices

screme

coorainates

ocut

range

devices

each

direction

irherent

ochysical

transformations

this

area

arproach

woulc

are

wnicn

still

ras

fine

must
forr

not

exnected
allows
enough

then

usaple.

tne

tecore

much

use

arproxiracior

G¢rarularity

REGIS

FUNCAMEANTALS...

achieve
the

1less

worst

Rev,

than

percent

resolution devices are
coordinate
transformation
of

usable

viewing

area

case,

High
any

loss

Page

the

usavle

viewing

expected

to use
algorithm which

nearly
exact
looses little {f

area.

3T FTITIELY"

NOTE

XXEEREERKEER

The screen coordinate option is not meant to be used
as
a
viewing
or
image
transformation (that is, define a coordinate
system which "makes sense" for
his
or
her
oroblem
.
this
should be done using higher level software),
It is meant rather
to provide a mecnanism for transporting image
definitions
frorm
one device to another while ensuring that the mraximum capability
0of a device is usable in the simplest
cases,
To
ensure
that
this
feature
1is
not mis=used, specific implementations should
perform some type 0of destructive operation along with the screen
coordinate

setup

operation.,

Such

sCreen

the
screen

vertical

is,

been

remaincger

this

1is

of
defined

pixels

#ill

with

the

not

autcmatic

screen

pverformed

clear

lieu

assumed

report, it will be
have
400 horizcntal

that

the

upoer

fcllowing

left

screen

assumed

pixels

that

corner.,

3CO
That

instruction

has

parameters

performed:

This

also

sets

there

deftault

5.1.3

Text

generally

increase
size
on

the

text

adjust

or
a

the

T(S1),

and

«(1,11)

plixel

size

adjustment

values.

option

floating

point

S(T(S<n>))

number

which

The
is

parameter

used

<n>
to

unifermly

decrease the size 0of the "standard" device character
multiplicative rasis.
As a guideline, REGIS assumes

nheignht of the stardard character

onee«tentnh

should

origin

S(s(0,010399,299],

that

such

oreration

cClear.

For

the

function,

one=thirtietnh

norizontal

the

size

ohysical

vertical

direction.

the

For

size

aporoximately

the

smaller

examcle:

S(T(S1.5))
will
be

uniformly
increased

cause
oy

size

percent.

each

the

screen

stancara

sizes

cocrdinate

ogtiocn,

this feature allows a transported image definition to te "tunrea®"
to
the
specific
«aqevice
characteristics.
Tre
option should
appear only once for each image definition
&énd
has
a
default
cvarameter

FIDELITY

4UfF

1.9,

IMPLEMEWTATIGHK

REGIS

FUNDAMENTALS...

Low

resolution

feature
not

Rev.

devices

all

capability

Medium

High

resolution

extent

S.1.4

Pixel

generally

and

vertical

text

Size

Adjust

pixel

adjust

performed

sizes

for

are

"point"”

point

feature,

once

may

some

expected

specific

The

usec

used

1lieu

size

least

argument
the

muitiolicative
size
image

the

available

pixels.

Ffor

in
-

a
the

<n>

horizontal

basis.
Like
the
acjustment
should
onrlvy be

and

normally

writing

have
This

options

icnored

the ability to
optior
should

pixel

multiplier

option,
sSignificant digits
after
the
decimal
point
wmay
interpreted
by
high
resolution devices as an extension of

number

implement
at

adjust

low=resolution devices which normally do
not
adjust pixel sizes on an incremental basis.
not

this
little or

capability

adjustment,

S(wi<n>]))
a

have

sizes.

numter

oixel

implement

incremental

have

character

putlication

floating

the

normally

sizes.

devices

range

expected

devices

character

reasonaovle

not

such

chanaing

resolution

adjusting

Page

are

since

characters.

example:

be
the

S(#[0.01])
#ould

integral

recognized

pixel,

request

use

100

pixels

between

each

REGIS

FUMDAMENTALS...

Rev,

Page

4¢

The POSITION Instruction
)

PURPQSE
REGIS assumes and uses
what
s
referred
to
as
the
"current
writing position®” convention for determininc where
a drawing instruction starts its operation
in
the
viewing
area,
This
means
that
a
REGIS
device
1is
required to
maintain the value of an X and Y set of numbers,
anrd
these

saved values are assumed always to be the starting point for
a drawing operation.
These
values
are
uyr=datec
to
new
values
after
each
drawing operation.
A simple example of
the
on

current value concept 1s the vosition of a3
drawing
pen
a
fatebed vlotter device,
The cuuyrent value of X and Y
also commonly reterred to as
the
"writing
cursor"®
or

are

"cursor" for short.
The purprose of the
is to move the cursor (change the value

position instructien
of the current X and
without drawing any visible image (that is, move
pen with the ren "up").,
REGIS allows the cursor

Y
values)
the plotter
to
be
moved
on
both an absolute
poth numeric X/Y parameters as well

<PINST>

<POPS>

GENERAL

]

<REGIS>

relative
pixel

basis

using

vectcrs.

SYNTAX
\'4

and
as

P<KPINST>

==>

[<pa>]

~=>

<pV>

<PINST>

<PINSTD

-=>

(<POPS>

==>

‘<KSKIPQ>

e=>

"CSKIPQ2Z>

==>

<POPS>

=-=>

<PGES>

<PInST>

<PINST>

==>

<PGPS>

==>

)

<PINST>

==>

<any=otherd>

<S«KIPI>

<POPS>

SE%ANTICS

The

position
{instruction
allows
the
cursor
to
bLe
direct X/Y parameters by using the form P[(<Kpa>].
The cursor oosition may be chandged pyvy relative pixel vectors
using
the
¢form P{<pv>}.
A tegin/end position btlock mav te
defined oy using the position options P(B) and P(E).

changed

S.2.1
the

Position Change
the

Cursor

described

earlier.

and

199

are

and

Arguments
changed

For

example,

FP[{<pad>]

The

relative

assume

respectively.,

the

Then:

form

<pa>

absolute

current

alloevs
oasis

values

as
X

REGIS

FUNDAMENTALS...

Rev.

P-Instruction

New

£(0,0]
P{30,23]
P(200]
P(,42]

20
0

allows

several

P-instruction,

<pa>

5.2.2

Pixel

which

use

relative

argument

Vector
"cnain

changes

pixel

used,

The

the
of

that

has

the

last

example

small

user

direct

sequence

current

multiolier

value

Instruction

New

X/Y

and

digits

for

value

each

set

sectior.

are

160

ard

Values

101

P0002

103

P01234567

100

P667

1205

105

€5

<pv>

moved

the

crogranms

the

current

avove.

allow

actually

in
as

pixels

defined

used

effact

supoort

allows
a

same

PO00000Q0000

110

P{+10]

110

the

1last
example,
direct
positioning
is
than pixel chains for large movements.,
effective use of pixelevector movement is to achieve
a
superscript and sub=-script operation in the context cf
text.

efficient

Position
options
and

arauments

{llustrated

value

REGIS

return®)

<pad>’s)

the

Generally,

the

1
1

end

"carriage

(multiple

techniques

instruction

S5.2.3

change

unit

(ANY)

graphics

<pa>

generally

cursor,

vectors.

options

Cne very
form
of

this

illustrated

Mualtiplier

and

absolute

writing

usually

(combination

relative

and

number

above

changed)

Positioning
= P{<pv>}

determined

changed)

encoding"

1is

Assuming
TV

for

the ‘'syntax

(only

(relative change)

single

the

P(10,20]{+5]

single

digit

0
23
50
42

valuye

P(15,20)

Although

are

X/Y

110

P{0,+10]

acces

rage

30
200
100

Pl{+10,-25]

then

the

seaguence,

the

current

intervening

Blocks

allow

F(E)

simple

returning

That

is,

the

value

drawing

and

P(E)

means

for

that

value

action
and

instructicns

The

ovecsition

recording

some

later

the

P(8)

ootion

After

which

rcecin

current

vevoint

generally

change

tre

cursor

ard

curscr

save

several

value,

REGIS

the

FUNDAMENTALS...

execution

restored

defining

since

images

allows

eliminated,
be

very

ot
its

the

Rev.

P(E)

original

which

ovrtion

value.

are

accumulative

particularly

rougnly

aporoximated

causes

This

have

roundoff

the

case

low

the

maximum

o0f

cursor

varticularly

useful

transportability,

errors
text

Page

drawing

resolution

occasionally
whicn

devices.

may

REGIS

FUNDAMENTALS...

Rev,

Page 49

S5e3
writing

PURPOSE

The
allows

image
this

writing
the

is to
means

adjustment

attributes

{instruction,

key=letter

¢to

the

which

control

be drawn at the
the
selection
to

pixel

manner

the

"u"
pixel

vixel level.,
In the REGIS
BRASE
of line drawing patterns and thre

sizes,

SYNTAX

<REGIS>
CAINST>

<WOPS>

wuser

GENERAL

]
'

Instruction

Attributes

<WINST>

==>

(

<WOPS>

-=>

[(<n>]1

ww>

KSKIPQ>

e=d

KSKIPQ2>

e=>

<digit>

==>

{Kdigit>}<uw0PsS>

wod>

)

<HINST>

-=>

<any=other>

the
a

Se3.1

<WINST>

<HINST>

REGIS

<SXIPI>

BASE

used

1in

allows the
solid lire

Pixel

there

structures.

multiplicative

vectors
form
as a

<KWINSTY

SEH4ANTICS

N=[nstruction

define

<WOPS>

the

user
or a

#4ultipliers

are

The

factor
and

only

two

signiticent

«w({<aa>]

allows

aprlied

bpe

instructions.

The

the

user

W(P<digit>)

to select a line drawing
dote-dash pattern,

pattern

recrresents

#{<n>]

The

arcument

<n>

pixel
such

numeric
constant which serves the purpose of causing each pixel
vector referred to by a P or V instruction to
be
repeated
the
numoer of times given oy that number.,
The pixel multiplier also
has affect on tne repetition lenagth of
1line
drawing
ratternse.
Devices
value

will
9ot

cnhange

non=integer

ovixel

general,

number,

hign-resolution

The

out

this

multiplier
the

value

&pixel

capability

multiclier
is

normally

devices.

following

are

examples

tne

Y11}

same

~{19]

2ach

<pv>

«~[(1]l,

(0,61

fine

adjustmnent

refers

tnis

feature:

defauylt
to

value

unit

pixel

oixels

the
may
used

default
Le

only

REGIS

FUNDAMENTALS...

Rev,.

Page

vector

size

device,

low

5«.3.2

ULine

Drawing

select

from

one

new

pattern

possible

values

Patterns
10

resolution

segquence

option

line

o0f

on/off

are

(to

(to be defined)

(to
(to

be
oe

P<olt><oit>,..

The
of

user
<pv>

pattern

the

user

patterns

define

vectors.

The

"“uc"

defined)

gefined)
defined)
user

defined
size

Allows
pixel

(1]

follows:?

Pl
P2
P3
Pd
PS

resolution

drawing

Draw image as if the pen is
(that is, no visirle image)
Draw image with solid lires
Dash pattern
Dasn Lot pattern
Dot Dct pattern
Dash Dot Dot pattern
be

high

cdevices,

W (P<digit>)

predefined

this

interpreted

line

definec

pattern

seaments

and

line

pash

Dot

pattern

interpreted
basea

upon

tyves.,

For

seguence

alternatinc

example,

the

sequence:

P111010
constructs

pattern

similar

the

line

Each aevice {s assumed to have a certain reretition
lencth
for
the
1line
drawing
ovpatterns.
This lenath is not required to be
standardized since it is assumed that a basic dot
pattern
will
carry
essentially the same information content independently of
this repetition period,
Devices
may
use
the
current
oixel
vector

multiplier

value

achieve

additional

discernible

expand
line

the

pattern

scacing,

tygces,

and

trus

REGIS

FUNDAMENTALS...

Rev,

Page

5.4
The

VECTOR

PURPOSE

Instruction

The
straight

Vector

instruction,
segments
of

1line

current

cursor

numeric

position

location

arguments

"v"

angle

tetween

new

positions,

one

pixel

used

draw

the

using

vectorse.

SINTAX

<REGIS>

==>

<VAPS>
:

GENERAL

[<Kpa>]

~w>

and

key=letter

artitrary

<pv>

==>

<SKIPQ>

e=>

~=>

(

<SKIP(G2>
<VGPS>

==>

<VOPS>

-=>

<VOPS>

w=>

<WINST>

<VOPS>

==>

)

~=>

<any-=other>

<KVCPS>

.
<K3SXIPI>

KVCeS>

SEMANTICS

Semantically,
manner

Jas

the

vector

P=instruction

instruction
with

the

"down",
That is,
the
v=instruction
image
to ve generated.,
The lines drawn

are

subject

the

We-instruction

the

current

the

onixel

current

and

the
vector

line

drawing

pixelevectors
nmultipliers

instruction,
The

polygon,

and

options

That

1s,

allow

the

time

interpreted, a line will be drawn
defined 8 (begin point) position.
The
a

ootion

temporary

instruction,
returned
of

Ficgure

the

¢to

allows

the

basis.

the
tne

value

values

user

the
which

same

the

visitle
instructicn
selected

drawn are suciect
selected
by
the

define
an

attriobutes
of

to
&=

closec

obption

the

completion

pen

this

pattern

back

writeing
they had

tne

that

causes

that

writing

After

works

exception

previously

the

attributes
cefore the

set

ornr

vector

will
©Gce
executicn

v=instruction.

gives

V=instruction

examrles

including

the

the
use

FINDELITY OF IMPLEMENTATIO:N

Kind

line

images

drawn

vatterns

usino

tre

Low

resolution

lines

by 4

Medium

devices

jagged

resolution

ahen

drasing

High

resoluticn

sufficient
appear

will

ncrmally

sequence

aevices

have

unit

size

varying

aoproximate

pixel

straiagnt

vecters.

degrees

quality

vectors.

devices
are
smoothness
that

the

naked

eye.

exprected
to
draw
lines
of
no
discernible
Jjagged
edces

REGIS

FUNDAMENTALS...

Figure

Assume that

8.,

Rev,

VECTOR

Page

INSTRUCTION

the writing mode is set

EXAMPLES

with:

W(PL)

then:

The

PI19Q1V(+440@]

saquance

gives:

VI+501(,+501(-501(,~50]

givaes:

V(+50,-5011(+100,+1001[+100,~100](+50, +501

With WI[10]

(pixel

size

cof

10)

gives:

then V01234567 gives:

O
with

the

pattaern

defined

by:

Wl41(P14101009)

Then

V[+2001(,+1001(-2001[,-100]

dives:
-

mee

ane

|
L]

The

sequence

CUEL

SES

instructions:

PL432,72]
Wi961V1456,
460P
48]
H(48]V642446064600
1468,
206P
361
WI24]1V46066424642202446424460645002066642446064
V6002060024220682066460

image:

=] [
=11l

encoded

]

chain

the

gdives

REGIS

FUNDAMENTALS...

Rev,

Page

5.9

The

CURVE

Instruction

Simple graphics devices do0
curve
generation
capability.
for at least four reasons;

1.,

with

the

assumption

processors,
having

The

curve

availability

the

device.

The

inclusion

completeness
and compass"

usually
feature

all

have
a
is bullt

devices

will

built
in
into REGIS
-

have

local

there is no longer any significant complexity to

local

substantially

that

not
This

recuce

capability.

the

local

number

curve

relative

drawing

curve

capability agives

the

idea of

primitives,

capability

characters

can

transmitted

REGIS

incorporating

dearee

tne

<cf

"rule

Each graphic device knows
its
abilities
better
than
the
software
driving
the
device
and
thus
1is better abkle to
select an optimal quality versus performance tradeoff curing
the
design
phase,
This
avoids
the common problem which
arises wnen a circle is aporoximated by an 18 sided
=zolvygon
on
a
low
resolution device which looks exactly like an 18
sided polygon on a nigh
resoclution
device
(instead
of
a
circlel),

PURPQGSE

The

curve

instruction,

keve=letter

"C"

used

draw

circles,
arcs of circles and curve interrolation seauences.
By a curve interpclation sequence is
meant
a
curved
line
inage
of varying radius of curvature such as would te drawn
by a drattsman using "french curves" or similar aids.
SYNTAX

<CURVE>

<REGIS>

==>

([<pa>]

-=>

‘<SKIPQ>

w=>

"<SKIPQ2Z2>

w=>

<digit>

-=>

(

<COPS>

==> C

<CCPS>

<CAPS>

<CURVE>

<KCURVED

<CURVED

<COFPS>

-=>

A<ang>

==>

<COUPS>

-=>

<COPS>

==>

<COF3>

e=>

-=>

LCOPS>

«=>

)

<KCURVED

==>

<anv=other>

KCUPS>

<Sh1P1>

<KCCPS>

REGIS

FUNDAMENTALS...

GENERAL

Rev.,

Pixel

vectors

normally

all

(<pa>]).

The

meaning of

wnhether

selected,
mean

which

tyces

sequence

not

the

option

point

tne

"smooth").
writing

5.5.1

curve

"S"

the

for

given

position

block,

the

usinag

argument

block

arc-angle

form

has

bpeen

argurents

option

within

curve

the

dependent

position

«circle",

operation

the

bounded

end
point
drawn.
In
curve

continuous

The

are

has

been

position

refer

intervolated

with

meaning

curve

first case, an
open
discontinuities)
1is
point

to coints on a curve through
is to be drawn.
There
are
twgo
jinterpolation
sequences
as determined by

curve

position

arc

interpolatec

0of

position

of
arguments

oosition

whether

not

have

arguments

circle"

"draw

position

Outside

"draw

selected
plock,

Page

SEMANTICS

command
upon

option

atctributes

using

initiated

beqin

curve
the

optien

"B",

tre

thre

(or
a
curve
with
second case, the end

drawn

back

the

begin

derivative

allows
the

(and theretore looks
cdefiniticn of
temporary

the

instruction

parameters.

¢Circles ané Arcs -.C{<pa>] forms
If

curve

instruction

oosition

block

has

been

form:

selected,

tnen

tne

thre

Cl<pa>]

will

dras

center

circle

and

witnh

(<pa>]

the

point

The cursor is left at
same instruction with

the
the

current
on

the

center
center

cursor

rositicn

circumference

after drawina the
option enabled:

that

circle.

This

C(C) (<pa>]

will the circle with the
<current
cursor
as
circumference
and
([<pa>]
as
the
center.
cursor

point

left

(eqgual

If
circle

tne
1is

enaing

<ang>

end

point

cursor

positive,
direction
the

circumference

point)

the

circle

degrees
©of

the

left

then
and

commnands,

from

arc

tne

that
the

center

the

arc

will

the

angle

«cirection.,

ocint.,

this

circle

ootion (A<ang>) is used,
starting at the peint on the

drawn

ooint

or
case,

the

tre
the
end

drawing.

arc=angle

<clockwise

circle

the

pegir

The

then ar arc of
a
circumference arc

cursor

left

tre

otherwise

the

(C)

option

the
arc.
If
the
anqgle
is
drawn in the counter-clockwxise

negative,

Figure

was

the

used,

arc

jilluystrates

will

drawn

examples

in
the

REGIS

FUNDAMENTALS...

5.5.2

General

Either
begin

Curve

the

Rev.

Interp

option

bounded)

"S"

start

Page

lation

(for

curve

sequence)

option

points,

the

position)

are

curve

image

curve

the

position
on

points

"B"

(for

a general curve interpolation sequence.
the "E" end option.
There
<car
be
no

The sequence {s enced by
intervening
circle
or
block
structured
P
or
within the range of a curve begin-end
seauence.
cursor

drawn.,

end

instructions
aithin
these

arguments (including the
curve through
which
a

The

points

protlem
1s

determing

handled

current
smooth

the

slope

the

following

not

imolicitly

mnanner.

The

positions

drawvn

but

end

points,

The

begin

curve

tne

are

and

bdy

the

end

using

point

start

used

For

the

veginning

poygnded

curve will
point,
As

slome

may be

"null"

repeated
of

the

sequence

the

"B",

continuous

this

svntax

curve

option

the

for

eacn

position
given

and

Figure

additional

always

tnus

the

point
so

this

not

information

that

derivative

tnhe

three
cosition

the

process

examples

The

must

seconc
is then

current

cursor

position

argument

curve

segment.

one

the

end

oposition

between
the
curve segment
last

closed

the

least

argument.,

case,
may

cursor

drawing

tre
that

retained

the

points

end

indicate

vosition

1illustrates

current

maintained

leads

also

included
{]

the

given to result in a visiole curve seament
and tnird positions given.
Gne additional
drawn

curve

sequence,

first

the

convention,

aadition

are
ot

visuvally

point

points

the

curve,

nave

result

arqguments

end

points
the

the visual aopearance
pe realistic,

and

define

curve

interpolation

instructions,

5.5.3
l.

Fildelity

©Low
3

implementation

resolution
polvgon

devices
3

vary

depending

upon

#will

normally

portion

such

Aas

the

will

certain

the

drawn

polygon

Bresenham’s

normally

number
radius

of
of

polygon

removed,

circle

arproximate

sides which
the circle.,

oQor,

that

the

end

medium

arc

little

and
or

aevices,

expectea

the

arc

algorithm

nigh

resolution
pe

cdiscernible

tne

definition

might

¢tv

also

with

alcorithms,

used

for

warnea
that
on
low
a circular arc may ce

should

not

degend

ugor

exrected

that

nositicning,

circle

no
to

imaqge

arcroximation

Incremental

low resolution devices.
The user
is
resolution
devices,
the
accuracy of

circies

»ill generallv
Circular arcs

accuracy

a3t

the

devices,

represented

Jjaagedness.
of

pixel

the

it
with

circular

level.

hich

high
arc

accuracy

and

resolution

gcositioning

REGIS

FUNDAMENTALS...

REGIS

does

implement
assumed

used

not

the

thact

Rev,

Page

specify

curve

will

the

algorithm

interpolation
be

similar

spline

w#hich

algorithm

nature

devices

but
the

S§7

{is

commonly

algorithms.
The
exact
curve sequence drawn
depending upon the algorithm used, but
this
1is
not
considered a problem since the essential informaticn
content -

varies

shown

Devices
algorithm

in spite

may

minor

implement

which

are

user

variations

than

accessible

one
by

the
curve

option

curve

rath.

intervolation
extensions.

REGIS

FUNDAMENTALS
... Rev,

Figure

0
X

CL+80)

CURVE

cursor

start

cursor

end

Page

INSTRUCTION

EXAMPLES

position
position

gives:

C(C)[+50]1

gives:

C(A180)[-401

gives:

C(S)II[+20,-2011+49,+4011+40,-401L+40,+401[1(E)

N\
C(B)[+150,-501[+150,+5011-150,
+501(E)

gives:

D
C(B)[+80,-1001[+12010-80,+1001(E) givas:

C(B)[+200,+15011+200,-15011-200,+2091 (E) gjives:

givas:

REGI S

FUNDAMENTALS...

Rev,

Page

5¢

used

5.6
The

TEXT

Instruction

PURPISE

The
draw

graphic

strings

text

instruction,

characters

key-letter

starting

"T"

the

current

cursor

position,
SYNTAX

<REGIS>

==>

<GTEXT>

CGTEXT>

==>
e=>

[

<digit>

<TOPS>

GEMERAL

e=>

‘<text>

~=>

Ctext2>

LGTELT>

-=>

(

==>

S<n>

we>

<AINST>

-=>

<TCPS>

e=>

)

<GTEXT>

==>

<any=other>

<GTEXT>

<SKIPI>

<TOPS>

SEAANTICS

Each REGIS
device
1s
assumed
to
have
a
built
{n
cnaracter
detinition
anc writing cavaktility.
The alohahet
for
w#riting
is
assumed
to
bhave
at
least
64
orinting
characters
and
in
general
will
implement tne full ASCII
printing set,
Each
character
of
the
<Ktext>
strinag
{is
written

placing

the

visual

1image

the

reterenced

character at the current cursor location.
After writing the
character,
the
cuyrsor vosition is changed to a soint «rkich
would ne the logical position for writing another
character

(normally
visual

nhorizontally

width

allos¥s

characters

varving

spoacing.

The

‘temporary
attributes
duration of a single T

S.o0. 1

Text

The
alle 48

Size

option

parameter
tne

user

distance

character).

The

little

written with varyinrg
w

option

allows

wnich
are
1in
instruction.

<n>

increase

generally
the

floatina
size

will

the

oction

and with

setting

4during

the

onlyv

point
tre

proportionately
the
sovacing
vcetween
mult iolicative
tactor
of
the
devices
Gene rallv,
tne range of <n> snould be limitecd
of

sizes

the

effect

than

size

= T(S<n>)

(and

valuy e

character

taken

reter

thne

numpber

characters

whick
crarr

cnaracters)
cy
3
"stanacarad"
size.
to
O
to
110,
.

default

value

REGIS

FUNDAMENTALS
...

S5.6.2
il.

Fidelity

Rev,.,

Page

implementation

Low resolution devices generally will have a
standard
size
cnharacter
which
will
wvary
considerably
1in size from one
device to another.
Thus the user should not cdepend upon the
cursor
and

value

should

the

reposition

end
the

drawing

cursor

bty

sequence

some

other

quality
of
character
representation at this
assumed to be poor and typically
drawn
as
a
short vectors Oor as a pixel pattern.
Medium resolution devices
good
aquality
characters

are

values
sizes,

and

must

implement

and

characters

meanse.

The

level is also
sequence
of

expected to
allow
reasonatly
deterministic enrnd point cursor

full

range

integral

character

High
resolution
devices
are
expected
to
draw
"letter
quality*
characters and give fractional as well as integral
character sizes.
Since tne
standard
(smallest)
character

size
on
a
high
resolution
device will generally oe very
small in proportion to low resolution
dJdevices,
the
screen
instruction
text
adjust
feature
may
have to te set wpnen
transoorting a graonic image definition.

REGIS

FUNDAMENTALS...

Rev.

Page

6.0
THE

EXTENDED

REGIS

LOGICAL

DEVICE

This section describes
Graphic
Device
required to
devices which are not common
not

meant

extensions
to
the
Logical
KEGIS
accomodate the sprecific features of
to all qrachics devices.
This
{is

exhaustive

discussion

the

rather an illustrative presentation which can
bte
the
extension
of
REGIS
to
device capavilities
here,

The

tully

case

raster

illustrate

the

CRT

devices

process

covered

extendirqg

subject,

but

followed
for
not descrired

some

detail

KEGIS.

6.1

Dimensional

Screens

Dimensional
screens
refers
generally
to
the
class
of
grapnhics
devices
1in
which
the
ophysical size of vixels has a
reveataole meaning and in varticular allows the user
to
choose
from

both

paper

variecty

such
devices
in
ophysical
extended

and

SDY

=«

sizes.,

oy allowing
dimensions.

the

SDX

pixel

photograohic

tollowing

Examples

plotting

such

devices.

cevices

REGIS

the user to define the
The
logical
device

size
1is

pixel

the

nixel

the

physical

size

direction

By
knowing
the
numoer
¢f
pixels
selected
coordinate
definiton
operation,
the
device
determine tnhe size of paper needed to draw the

The units
selectanple
oy

of pixels
therefore

parameters:

is the pnysical size
norizontal direction

vertical

include

accomodates

of the
ohysical
the user with the

bty
tne
1s
then
image,.

measure
should
hne
metric svstem veing

screen
acle to

opticnallv
the default

valuye,

These devices also will
generally
allow
(and
need)
the
of
1line
seagments to be user controllacle.
This tyce ot
feature w~ould pe included in REGIS by using a
wiath
c¢prtion
in
the w~writing actributes instruction.
.

wiath

0,2
-

Gray

Scale
Tne

ability
draw

and

Color

simplest
o0f

aifferent

recresents

tne

form

rlotter
colors

cclor
device

caparcility
to

use

refers

cdifferent

caper.

tnis

Lfackground

<cclor

ana

the

colorec

case,

gsens

the

tre

pens

trcC

rpagper

represent

tre

REGIS

FUNDAMENTALS,.,.,

foreground

color.

Rev.

Black

Page

and

white

inherently
have the ability to
lignt, called gray-scale,
More

resolution

full

color
raster
devices have
of color hues in acdition to

range

capability.

allows

for

REGIS

the
of

pixel

has

clear

Ihe

simplest

high

numbers

scale

the

valyes,

present a
(intensity)

color

the

The

oroaacast

user

plotter

raster

color

and

rut

highest

the

scale

the

which

been

work

Color

little

meaning

scale

trightness

intensity

eight
colors,

anc

Qgray-scale

tne

cray

three

white
and

established

for

summarized

and

packground

nas

primary

rclack

between

television

SN OLW
-O

three

the

nave

wrhich

controllable,

cdevice,

attriosute

and

intensity
color follows
enctocraghic
tne

foloowirg

valuye

Blacx

(dark)

Blue

Red
Magenta

Green
cyan
’

Yellow
wWnite

This 1s based on
transformation
used

standar4d).

nroad

grev

7):
4,1%G

cdevices

2.,1*%*R

navinag

the

standard

the

range

to
luminance
inaustry (#dTSC

transformaticn
is

(norrmalized

for
to

level
color

devices
the

range

cararilitv,

tre

0.5%8

€fuyll

range

svstem

adooted,

floatine

oo0int
numbers
to
zarameter value:

summary,

FRGB
television

accurate
scale

due=i,ightness=Saturation

intensity

forearound

mapolng

and

lowest

colors

conventions

it
which

foregrouné

devices,

the

scheme

in a simnle
manner
access to the broacd
most
cacacle
of
the

intensity

interoreted

trie

naving

capabilities,

following

device,.

Gray=Scale

the

table:

scale

full

with

between

form of

comglementary

devices

levels of
as
high

grav-scale

actribute

case

reoresenting

simpla

acility

the

npas

associated

resolution

raster

values

For

and

cagabilities

differentiation

the

range

adopts

still

"intensitcy"

for

For

the

gray

‘

MOst

color

ovut

attrioute

vackground

broad

device

dgdevices

spectrum
devices:

Tne

tnis

logical

selection

simple

Each

qraphics

accomodate

extended

raster

show varyira intensity
complex devices,
such

this

system

coler

color

reguires

used

aefinitior
three

cefinirc

1is

gareraliliv

scecific

REGIS

FUNDAMENTALS...

Hue

(H)

Rev,

Page

The hue of the color expressed
an angle on the color wheel,

Lightness

(L)

= The

relative

color expressed as
full brightness.

Saturation

(S)
the

brightness
a

= Expressed as
fully

saturated

percentage

the
of

percentage of

hue,

For the purpose of converting between the low=-resclution RGB
notation and tne higner resolution HLS system, the following
taole ‘should be used (generally,
ligntness
and
saturation
are

ignored

anag

TC CONVERT

Hue

only

#HLS

the

hue

angle

has

meaning):

RGB:

Lightness

RGB

Intensity

8S
&5
85

B
M
R

Il
12
I3

331
31
51

to
to
to

30
90
1S90

15
1S
15

to
to
to

151

to 210

211 to 270
271 to 330
(any)
(anvy)

15
15
G
85

to
to
to
to

85
85
15
100

G
C
D
N

14
IS
I0
17

TQ CONVERT

Intansity

RG3

HLS:

(Saturaticn

Hue

0
B
g
R
G
C

0
0
60
120
240
300

0
S0
SO
50
SO
S50

Ia
17

Y
N

180
130

SO
160

image.,

on
3
vyellos
extreme ranges

tnhe
the

That

intensity
foreground

is,

we can

130}

Lightness

10
It
12
I3
I4
15

In
conceot,
indevendently
to

grapnic

RGB TO

piece
0of
raper.
of implementation

parameter
can
be
apclied
Aand to the pgackaround ¢f tne

select

yse

3 clye cen

draw

Cbviously,
devices will have
0f the intensity attritutes.

5.3

Taxt

Attrioutes

faxt

attrisutes

associacea
sion
incluaing (out not

incluce

wide

varierty

features

the
presentation
of
textual
cnaracters,
limiced to) any combiration of the followirc:

REGIS

FUNDAMEN[ALS...

Varliable
height

character

Angular

Alternate
forth).

Superscript

Overstrike

lanquage

and

svecific

generation

#ith

support
device

extended

independent

angular

device

The

character

width

The

HANG

The

TUX

The

mneasured

TDY

the

heiqht

the

degree

charateristics
of

the

<these

areas

features,

definition

hvoothetical

the

degrees

the

character

relative

ot
measured

is
image

extenrded

the

follewing

rcarrallelogram

parallelocram

pixel

measured

1is

width

line

horizontal

measured

axis.

side
of
the
to
rthe
width

characters,

norizontal

vertical

scalar parameter
fonts

the

for

charactsar
direction

Italic

spacing

two

<characters

srvacina

two

characters

units.

relative
pixel

the height
relative

FOAT

features
that

capabilities.

forth).

written,

measured

possicle

units.

relative

The

one

portability

direction

and

parameters:

direction

these

therefore

such

sucports

cevice

suppcrt

recognize

the

angle

support

#anich

DANG

1is

Futura,

and

should

majority

wIDTH

REGIS

the
@ay

(Gothic,

APU characters,

user

(relative
slanting
representation).

spacing

capability.

least

parallelogram

and

provortionral

and

fonts

the

logical

HEIGHT

and

pixelevector

including

characters

subscript

The

oroad

width

fonts.

intent

extremely

(underline,

set,

spacing

representation

the

extension

independent

spacing,

including

‘

orlentation

Foreign

size

character

REGIS

Page

lettere-spacinag.

character

snicn

adjustment.

Variaple
and

Rev,

units.

used

currently

identify

use.

which

several

REGIS

FUNDAMENTALS...

Rev,

Page

6.4
Area

Attributes

This

class of extensions refers to the
general
capability
devices
to
associate
attributes to areas bounded by
REGIS primitive line images.
The visual attributes may
1include
compbinations of the following:
of

many

Shading

Color

These

patterns

and

intensitv

capabilities

extensions,

the

boundaries

FILLed areas

concept

covered

two

approaches

area:

An area

sequence

line

are

distinquishes

defined

vectors

and

other

bounded

either
end

SHADed areas = An area defined to be the differepnce
two

The

not-necessarily

first

case

surface,
used

bounded

corresponds

The

second

represent

data

case
as

vector

curve

the
common
corresponds to

"histogram®

point)

between

seguences.

concept
the

REGIS

identitfying

(closed

curve,

patterns).

variation.

syntactically

REGIS

bounded

(similar

oounded

tyoical

approach

image.

6.5
Dynamic

Attributes

The

area

features

attribuytes

and

The

common

that

the

attributes covers
illustrated
at
one

the

voint

other

time,

interpreted

visual

dynamic
are

extreme

REGIS

for

foreground/packground

function

wnicn

Using

this

broad

fully

function

model

tvpical

the

spectrum
by

of
"rlirking®

animated

capabilities

selector

alternation

attributes.

such

extreme

foreqround

cartoon.

the

nction

varies

blink

and

attribute

Eackground

B.6
User

Interaction

User

devices
result

several

interaction

operator

computer

possiolie

return

reters to
informatior

send

cdevices,

character
regquest.

queery

and/or

the

general

the

operator

Generally,

seqauences

capability

controlling
entry

REGIS

resoonse

using

expects

such

computer
such

one

some

a
of

gevices

computer

REGIS FUNDAMENTALS...

Rev,

Page

7.0
STANDARD

RASTER

This

EXTENSIONS

section

extensions
addicional

describes

to
be
uysed
capabilities

standard

with raster
accessible

set

REGIS

instruction

CRT qraphics devices.,
The
wusing
these
extensions

inclnde:
1.

‘

Background and

foreground

grayescale

and

color

intensity

attributes

(wnhite

black,

black

attributes,

Negative
and

image

Screen

The

demory

area

scrolling

6.,

Area

attributes

for

bcunded

Text

attrioutes

and

user

"alternate"

The

syntax
190,

attrioytes,.

(screen

(tlink)

value dependent
in addition to overlay

figur=

white

fortn).

the

Figqure

dvnamic

attribute.

writing

attributes
writing).
and

unbounded

definable

instructiocn
11

motion),

writing

areas.

characters,

extensions

summarizes

(replace

the

svntax

summarized
of

the

|{n

intensitv

REGIS

FUNDAMENTALS...

Figure
1 INST.

10.

IPARAM=1
ETER |

KEY

Xi
|
X1
X1
Xl
X1

{
!
I
{
!
|

STANDARD

Rev,

RASTER

PARAMETER
VALUES

|
|

<pv>
[<pad]
(
)

Page

DISPLAY

EXTENSIGMS

MEANING

Move screen image by pixel vector
Move screen image by <pa>
Extended options
negate (reverse) the irage
disacle negative image (default)
set packground intensicty

N<DD
NQO
I<intens>

amount

.'-'----‘---‘--’--------------'---------

Xt
Xi
Xi

i
i
{

(

--------------------------------------.

)

A<n>

}
{
|
|

N<ND
NQ
E
C

Xl
Xt
X1
Yi

{

|
[
}

v
S

<digit>

*<char>"’

{

el et

enatle

Xt
Xt
X!
X\t

{
Xi
X!

Extended

I<intens>
e

(<ra>]

(

‘

writing ooticns
Alternation (blink)

disable alternation (default)
enable negative image writing
disable negative image writing (default)
erase writing
complement writing
replace writing
overlav writing (default)
enable area shading
use <digit> line pattern as fill cattern
use character as shading pattern
disable area shaaing (detault)
set

#riting

D D

intensitv

Set

relative

}

A<digie>

}

alpnavet

Si{<aa>]

set

{

avsolute

M <aa>]

set

row/column

set

Italic

)

Extended

1 4]

I<ang>

v<ang>

el e

text

LOAD

smacing

options

(font)

select

character

pixel

row direction

ALPHABET

CHARACTER

‘<char>°’

<text>;

i
l

P
|

(

{

S{<aa>]

{

character

i<intens>

definition

cackground

intensity

{

Character

pattern

)

select

loaded

definition

hexa-decimal

GRAPHICS

Identify

IMSTRUCTION

character ootions
select decimal number

READ
(

character

Load

{

Select

size

T TSSO

)

row/column

multinliers

slant

set cnaracter

text

read

base

size
select

PARAMFTERS

parameter

current

tase

nurter

to bte read
cursor nosition

Figure

11.

RASTEZR

EXTENSIONS

INTEMSITY

PARAMETER

MEANIMNG

<intens>|

INTENSITY

|
[
|
i
|
|
i

<digit>
¢
)
D
8
R
G
o

{

|
|
|
|
|

ARGUMENT
Set one 0of 3 predefined
Intensity options

dark
blue
red
green
magenta

(default
(defauylt
(default
(cefault
(aqefault

cyan

Y
W
1<ang>
L<ocnt>

(default

IS5)

vellow
(default
white
(default
HLS hue angle
HLS liachtness in

I6)
17)

sS<pecnt>

HLS saturation

intensities

IC)
I1)
12)
13)
I4)

percent

REGIS

FUANDAMENTALS...

Rev.

Page

7.1
Screen

Instruction

Extensions

PURPOSE
Raster

setting

scan

extensions

the

screen

instruction

allocw

the packground intensity (color and/or gray=scale
reversal
of
the
image
intensities
and
screen

value),

*scrolling®,

<SCREE{>==>

<SOPS>

[<aa>])
<pv>

==>

(

==>

N<KN>

==>

<S0OPS>

-=>

GEHERAL

<digit>

w=>
<ITOP>

(

<ITOP>

==>

DIBIRIMIGICIYIw

==>

fa<ln>

-=>

L<n>

-=>

S<n>

-=>

)

SEMANTICS

~Tne forms
"move"
in the

(<aa>]

and

viewing

CRT
any

devices allow text
positive
no-zerc

the

screen

the

system

precise

These

color

forms

capaoility

scrolling

the

allow
the

number,but

gray=scale

colors,

the

screen

same

way

The

forms

secondary

setting

are

[<aa>]
included

cerforming

“strip=

feature,

level

7.00000,
the

the

this

most raster
HN<n>
(<n>
is

chart"

the

and
<to

screen

colors

color

value

througn

feature

dark
bty

and

scale

{

the

white,

usina

the

cor
HLS

<pv>
allow

motion

ceneration.

range

set

selection

devices

for

Since

the

this

implementation

ranging
rrox
no
implementation
at
all
to
"panning* operation of allowinc the ooerator to
window

image

that

usually

definition,

Screen motion

dynamic

scrolling,

(minimum)

orimary

7.1.1

ajllows

0,00000

eignt
a4

<pv>

area

1) and N0 reverse
image (black on white or vice
versa)
and
cause
"normal®" imacge to be shown respectively.
The intensity

parameter

e=>

the

dynamic

case

is
is

text

curely

verv

broad

the

full

move

the viewira
jintent
of

much larger image definition.
The
summarized in tne folling exaroles.

scale

. REGIS

FUNDAMENTALS...

Rev.

Page

S(,#+201
move

the

screen

image

right

the

equivalent

"one"

text

line:

SO
move

the

data

item

7.1.2

many

screen

Screen

stripechart

image

These

options

raster

scan

the

device

written

reversal
allow

CRT

pixel

u<n>

access

devices

normally
dark

one

make

room

for

the

presentation.

presents

background

and

the

inherent

"reverse"

their

characters

and

then

invocation

capability
image.

lines

the

That

is,

white

S(n1)

option

will show the image as a dark line
on
white
backaround.
The
option
sequence
S(#H0) then would return the imace renditiorn to
its normal impression (#0 is the default value).
In the context

color,

this

reverse

the

cyan

and

forth).

significant

7.1.3

feature

color

have

meaning

(blue

Screen

reversal

becomes

inensity

intensity

parameter

(ignored)
vellow,

should

information.

B3ackaround
The

may

values

not

red

used

bvecomes

used

carry

I<ITOP>
the

screen

instruction

used

changed

uniformly
change the background intensitv of the araphic image,
The intension i{s the same as loading a certain colored plece
ot
paper

into

during

tne

orocess

value

cthe

color

the

essential

olotting

"off"

device.,

drawing
pixels

rectangle

encloses

should

defined

background

either

the

then

uniformly

define

use

the

resolution

devices

the

color

generally

gJray=scale

primary/secondary
values
to
these
or

case,

background

integral

attripute

current

may

define

fattern,

which

transportaoility.

the

line

c¢ontent

operation

Low

pvarameter

image

information

dynamically

This

the

but

placed

such

action

ensure

backgrouna

maximum

screen

erase

intensity

crayescale.

will

only
values

color values
but
inteqral values if

color

backaround

character,

and/or

the

must
they

implement
and/or

convert
support

at most
the
6

the
HLS
agravescale

color.

Hign

resolution

levels
colors.

devices

gray=-scale

are

required

levels

to
on

suceort
eacn

least

the

crimarv

REGIS

FUNDAMENTALS...

Rev.

Page

7.2
writing

Attributes

SYNTAX
Raster

allow

extensions

access

including

color,

attrioute,

image

to the writing attributes instruction
range of capabilities ct CRT devices,

wide

gray-scale,
"memory"

the

simple

modification,

bplink

and

area

dynamic

filling.

SYNTAX
<AGPS>

KFILL>

Extensions

GENERAL

The

tne

7.,2.1

N<Nn>

N0
E

-—d

==>

-=d>

<WOPS>

<4a0PS>

==>

S<FILL>

==>

I<intens>

==>

<digit>

-=>

‘<&char>’

nil

forms

"on"

and

disable

identify

pixeis

enaoled

positive

1integer

Ccause

pixels

tne

Ine

concept

#111

for

area

tne

some

the

all

oe
for

intensity
a0

the

attrioute

suobsequent

dravwing

blinking

used
options

are

modify
used te

I<intens>

torm

intensity

|{is

(value

does

aA<n>

from

pattern).

device

not

irage

visually
a

turn

oction

A<n>

generating

the

value

being

instructions.

attribute

that

then

form

disable

character

image

time

using

the

and

form

are

writing

The

aternate

and

written

and

alternate

backgrouna

enable
a

= A<n> and AOQ

2link

period

and

oattern

visually

underlying
sequence,

R,
S<n>

filling

line

using

alternation

1intensity

used

foreground

usually

foreground

already

are

©portion

Alternate attribute
~hen

image

The options £,
memory.
The

and

A<n>

anr

image

used

==>
ow)D

<uGPS>

<HWOPS>

=-=>

attrioute.
enable

A<n>
AQ

SEMANTICS

writing

the

==>
==>

ard
off

obut

rate,

section

drawr

show

repeat

tlirking

only

with

time

then

associatec

decendent

snown

oeriod

(<n>

instructions

for

the

this
cixels

disables

witnh

tre

vcixels

tre
in

REGIS

FUNDAMENTALS...

7.2.2

Memory

Rev,

modification

Page

R,C,E,V

For

devices

wnich

some

save

sort,

these

the

memory

options

allow

the

basis

elements

rules:

the

pixel

image

dvnamic

defined

memory
device
modification of
by the following

V ootion = overlay the new line pattern or
characters
onto
the existing memory pixels ...
that is an "OR" opveration of
the "On" pattern or character pixels.
This {is
the
default
REGIS
option
and
means
that
lines
written
over
text
Characters
«#will
appear
visually
to
strike
throuch
the
character.

R option = Replace writina causes
the
1line pattern or craracter toc
independent of the current memory
locations,

ontion

pattern

Complement

character

the CN and
be written
values
at

writing

pattern

causes

GFF
intec
the

the

"XGRed"

pixels
in
the memory
addressed

current

with

the

image in such a way that if the same
sub=image
is
twice at the same oostions, tne result would
apprear
writing nad teen performed at all.

€ ootion

Erase

suosequent

bacxground

written
would

the

oOor

tne

oction

Note

that

tnese

can

not

"R"

w#ill

over=ride

option,

7.2.3

Area
These

snading
option

four

same
ot

adcressed

revert

all

subsequent
given

octions

combined.

the

S<n>,

forms

allow

are

every

pixel

were

screen

clear

current

value

mutually

That

is,

devices

vector

and

until

(disables

€illing).
the

filling

their

the

S‘’<char>’

<digit>

pattern

effect

0of

the

tne

exclusive

and

invocation

anc

The

currentlv

curve
the

form

selected

with

built

instructions
execution

§S’<char>’
alchabet

tre

the

“yw

S¢
in

capabilities
to draw an image uniformly filled with
intensity values.,
The sS<diqit> option invokes area
pattern

written
3as {f ro

pattern.

generally

option

values
to

Thus,

the

inaeoendent

line

pixel

values,

achieved

memory

all

instructions

selecter

with

causes

drawing

1line

current

area

(usirag
the

the

aliows

used

fillira

the currert
filling
for
line

orvrtion

character
&8s

the

pattern,
Ihe actual operation certorvecd by the device
is
dependent
upon
whether
the
subseauent
instructions
are
defined to ne oscunded lines/curve sequences
are ocer seciiences.

OPEN

SEQUENCES
In

begin

this
()

follows,

case,
ard

Ihe

the

end

value

V
(E)

instructions

ortions.

recorcded

tre

The

are

action

tire

that

net
taken

the

aqaiver
is

S<r>

REGIS

FUNDAMENTALS...

Rev.

Page

option is invoked is used as a vertical reference line,
All
subsequent V instructions
are
then
drawn
as
four
silded
figuyres
with
this
reference
1line as the base, the vector
drawn
as
the
top
(bottom
if
the
vector
1is
below
the

reference

1line)

and

the

vector

start and end polnts

are

taken to be tne coordinates of vertical lines wnich complete
the four sided area.
Several vectors drawn in this way will
tnen reoresent a form of polygon which generally has several
closed
sections.
Curve instructions definea by the (§) anc
(E) ootions are drawn as if the curve sequnce
consisted
of
infinitesimal
vectors.
Note
that
the
vector
and curve
sequences may cross the
Y
reference
1line
anvy
numper
of
times.
)
2,

BOUNDED

SEQUENCES

This case s distinguished from the open
case
by
the
appearance
of
begin ana end ooticns in the vector or curve
instructions,
1In the case of the
vector
instruction,
the
positions
specified
petween (B) and (E) options (including
the initial current value) are
taken
to
pe
points
on
a
closed polygon and the entire bounded area is filled even if
there are enclcecsed image segments (which will get
overlayed
or replaced as a function of the current memory modification
option

value).,

cayse

the

Similarly.,

complete

the

area

bounced

curve

defined

secuence

the

sequence f£o be filled.
The circle curve
option
considered a closed curve anc therefore dces not
oegin end ovtion scecifications,
Tne
scecial
circular
arc is handled
cf a3 "pie" c¢cnart.

The
pattern
0of
or

shaaing

¢to

£ill

enable

tne

the

arc

option

S<Kn> will use
vertical direction,

will

irtercolation

1s
always
recuire the
case
of
a

cefinec

gplece

the

selected
1line
4Aadcditional opticns

the snading option allow the use 0f a orecdefined line rattern
user
defined
pattern for the horizontal airection as well,

Alternately,
the
wuser
may
refer
to
a
previously
defined
character
as
the
¢filling
pattern in which case the cnaracter
pattern
1s
replicated
sufficiently
to
¢fill
the
area
with
aporopriate
clipring of the bounaaries of the characters at the
edges

the

poiyaon

curve,

simulate
the
area
croass—-hatcning patternse.
efficiency,

area

vectors.

open

cooy

devices

should

not

may

choose

by
acproprtiace
transport,
a&ana

simulated

seaunce

Figure
both

tillina

Hard

filling
operation
To
acnieve
maximum

and

{illustrates
pounded

several

vector

and

examples

curve

area

seauences.,

fillina

for

REGIS

FUNOAMENTALS...

Figure

12,

Rev,

Vector

Page

and

Curve

The shading sequence W(S1)VI+300,-100]

Extensions

Examples

dives:

If this same shading sequence is used with
the pattern
S111110140 then the following pattern shaded
triangle is drawn:

Bounded

polygons

can

filled

using

the

(B)

and

V(B)[+50,-5011+99, +501(-60, +401 (=}

(E)

options:

Curves may shaded relative to a y pasition as
in the
case

vectors:

C(S)[1[+59,-3911+50,+601[+70,-601

B
or

shaded

boundad

filled

area,

...

for

[1(E)

the

C(BI[+150,-10011+150,+1001[-150,+1001(E)

instruction:

REGIS

FUNDAMENTALS
... ReVe

Page

7.3
Text

Instruction

Extensions

Extensions
for. grarhics
text
include
user
character parareters and user definable alphatets.

definacle
:

SYNTAX
S<TEXT>

==>

(<ra>]

<TOPS>

==>

<digit>

«=>

[<aa>]

<TOPS>

-=>

[<aad>]

<TNPS>

~=>

<angle>

<TOPS>

==>

]

<angel>

<TCPS>

<REGIS>

==>

<LOAD>

==>

[

<SKIPB>

==>

(

<LOPS>

7.3.1

Text

-=>

‘<text>

<text>

<KTCPS>

<LCAD>

<LOAD>

==>

<LOPS>

-=>

<LOPS>

-=>

(<aa>]

-=>

)

instruction

<LOPS>

extensions

Figure 13 summarizes the
parameter
ccntrols.,
These

user
selectable
text
character
rcarameters
are
summarizeag in the

£ollowing.

T{<ra>]

= The

define

tnhe

relative

nosition
and

aragument

changes

<ra>
bhe

used

3acvplied

after

each character s written,
These
exclicit
oparanmeters
are used even thouah consecutive characters may overlapo,
S[<aa>] =
<aa>
are

The X and
used
to

character
size).

rectangle

M({<aa>] =
<aa>
are

The X
uysed

and
to

the

wicth

myltiplier

aoplied

portions ot the aovsolute
argument
define
the width ana height of the

drawn

gzsortions of
define
the

ard

selected

heicht,
so

that

(ron

size

anrd

colump

Generally,
the

row

size

the

wictr

divided

the row multiplier is the same as
the
c¢haracter
=idth
measured in pixel vectors but may pe cifferert from this
value f£or special ourrvoses.
In rcarticular, fewer than &
nultiple
number
of pixels mav ce drawn so that not all
0of tnhe cnaracter is
drawn
or
more
than
an
1intecral

REGIS

FUNDAMENTALS...

Rev,

number

pixels

pattern

repeated,

D<angle>
of
the

and

are

drawn

which

case

the

character

= Direction selects the angle which
the
width
character makes relative to the horizontal axis

given

in degrees,

I<angle> = Italic
height
(columns)
character

angle specifies
the
of the characters are

the direction of

current

Fage

the columns as

direction,

angle
that
the
written relative
defired by
the
then

REGIS

FUNDAMEMTIALS...

Figure

13.

Rev.

Text

Page

Parameter

. k—

Extensions

—

Initial

inal

Cursor

cursor

position

R
N
.
D<direction>

/
CMUL

I<Italic

/ CSIZE

RHUL

RSIZE\\{{/

DEFINITION OF PARAMETERS
DX

change

DY =

change

CSIZE

RSIZE =

column

position after writing
position aftar writing

size

row size

CMUL = column
RMUL

= row

dot

multiplier

D<angle> = row direction,
?® <= <angle> <= 360

I<angle>

Jtalic offsat

range

of:

Position

REGIS

FUNDAMENTALS...

7.3.2

Pace

REGIS device
variation
as

characters.

These

"“A"

option

alphabets

are

numbered

modified

REGIS
memory

syntax
ASCII

1Is

may implement
several
alphabets
1including
well as foreign language and graohic symbol
alternate

the

text

alphabets

syntactically
always

content

the

except

are

each

character

pattern,

The
on

The

1Is
the
separated

and

representation.

specifies

number

o0f

size,
By
left most

row

alphapet
may

the

detinition

row

communication),

option
the

<characters

patterns

instruction

size
color

(the

bpe

character)

parameter,
to

the

ancd

bv
the
to the
numeric
the

the

(most
¢first

decimal

selection
of
character
base for definition.
In

user

manner

I<intens>

associated

the

generally

defined

efficient

the

are

hrexa=decimal

most

allow

1loaced

dgiven

general

refer

sirgle

not

default, the row patterns
displaved rixel and
the

selects

S[<aa>)]

ocackground

sequence
of
row in

load instruction oovtions allow
an
alghabet basis and number

for

used

the

differentc-

The

for

top of the
by commas.

particular,

the

set

distinguishabrle.
character

which

implies
the cnaracter
significant bit is the
integers

national

font

usinag

allows one or more of the alphabets 1, 2, eee
loadable
wusing
the
LOAD instructionr.
The
a load instruction is tne letter "L" followed

parameters

varameter

selected

instruction.

of
cnaracter
index
whicn
will
be
character and tnis is then tollowed by
a

size

User defined characters = A cption anéd L instruction

font

pbe

Rev,

with

number

base

for

cdetine

the

similar

option
specitic

base
line

size

the

of
text

allows

character

definition,

Figure
instruction

14
and

illustrates
examples
the L instruction.

the

extended

REGIS

FUMDAMENTALS...

Figure

14,

Rev,

Page

Extended

TEXT

Instruction Examples

Using T[+19,+91(A0,54,D0,10)
[
21

Using

TI[+20,+01(S2)'ABCDEFG’

gives:

ABCDEF
G
Using

TU+30,+01(S3)'ABCDEFG’

gives:

ABCDEFG
Using

TI+190,+301(S9,I-45)'ABCDE’

gives:

AL LS
(direction

up)

and

I45 gives:

character

defined by:

SRhER
&

Using D3¢

Using the

alphabet

L’A’88442211884422118844;
then T(AL,S[290, Zel,flti 21)7A’

The

samne

character uzth

gives:

T(th 2l)

gives:

A
Y
Note

that

primitive

this
of

type of
bar

character

chart

drawing

can

used as

progranm,

the

REGIS

Read

Parameters

Rev.

Page

Instruction

=«

PURPQSE

The read
wuser
to

the

varameters instruction, keveletter "R"
allows
read
back
to the "host" computer (source of
instructions) parameters of
the
drawing
process
|in

REGIS

interactive

environments.

SYNTAX

SRINSTD>

==>

==>

Y W

<REGIS>

o=)

<ROPS>

GENERAL
.The

position

<RINST>

<SKIFC>

<RINST>

—e)

7.4

FUNDAMENTALS...

e=>

<digit>

==>

<RCPS>

-=>

<ROPS>

==>

)

<RINST>

-=>

<any=other>

cotion

the

<SKIPI>

SEMANTICS
R(P)

coordinates

the

and

host

environment.

The

general

sequences

the
response
string
character strings.

numeric

terms

syntax

strings

the

The

<header>and

which

allow

the

scurce

cursor

{in

the

are

vosition

definition.

implementationr

garaphics

the

<Y=part>

writing

current

<X=part>,<Y=vart>

<Xe=part>

current

causes

transmitted

interactive termirnal
response is:

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Page 82

hardware

instructicens