Digital PDFs

XX-20CA9-B2

May 1967

16 pages

Original

0.6MB

view download

OCR Version

0.6MB

view download

Document:	08
Order Number:	XX-20CA9-B2
Revision:	0
Pages:	16
Original Filename:	08.pdf

OCR Text

CONFIDENTIAL

- PDP-X Technicél Memorandum #-8

‘Title:

‘authbr(s):
:

small XYy Display

= H. Burkhardt
I..

Seligman

Index Keys: -.Display
IO

Peripherals

Distribfition
Keys:

Obsolete:

None

Revision:

None

Date:

July

11,

1967

o
-

'Ovérall fiescriptidn

This display is a replacemenf for the 34 oscilloscope display

that is often sold én PDP-9 and PDP—8.

B can be used to drive

The displéy controller

é.

Techtronix 503 or 564

Conrac typé XY scope

|
|

C. —Storage tubes as they become available

|
'

1. General

Specifications

' The XY display may be used for graph
plotting, character plot—
ting or other forms of non-comp
licated graphics.

The control

well

"raster mode"

facilities

for

facilitate

the

individual

registers
and for adding data words
registers.

Four

being

the

data

The

axis

are

intensity
displayed

resolution

bits

levels
to

one part

character generation
X

and .v

axis

to the individual

axis

are

available

allow parts

accentuated.

256,

i.e.,

the

axis

registers

length.

includes

Programming

The

XY display

controlled

setting

changing

bits

its

status register by use of the IOC or IOX instr
uctions respectively.

iThe status register
may be sensed or tested by use of the I0S or
%

IOT instructions

respectively.

The display contains two 8-bit registers,
register
a

and

position

the

Y-Axis

on.the

face

(0.377)

the

These

display

two

registers

define

screen:

(377,377)

deéignated the X-Axis

(0. 0)

(All numbers are in octal.)
(377,0)

The X- and Y-Axis registers are loaded with data as indicated by
the

contents

the

control

fields

the

Status

poinis
t then intensified'as indicated by the contents of
the
BRIGHTNESS bits of the Status Register.

Data may be
structions

sent
or

directly

through

the

display by means

multiplexor

channel.

1In

IOW

either

inEaseg

the display will operate upon the received
data and set the
REQ

bit

its

status

done.

H81ff?f

TM~

3'1-’InStrficti6

_Thevdisplayffiiliiféspondito all IO instructions issued by the

central processor when- the DA (Device Addressj field contains

the address
of the display.

The instructions IOC, IOX may be

uséd to alter the contents of the Status Register.

The instruc-

tions I0S, IOT may be used to sense the Status Register.

The -

IOW instruction may
be used to transfer data to the display or
the display may be

used

a multiplexor-channel

mode.

The

IOR

Y-AXis

X-AX1s

3.2

Maintenance

There

are no

3.3

.Data

Data

instruction may be used to read back the X- and Y-Axis registers:

Instructions

special maintenance

instructions.

Formats

read by the display either one byte or two bytes

£ime depending upon the mode of operation establishea by the contents

of the

Status

the

display reguires

two bytes

- of ififormation, they will be transferred to the display by means

of an IOW'instruétiQn or under control of the multiplekor channel.
The

3.3.1

format of this

depends upon mode:

Point Mode

Two bytes
‘bits

data

are

the

reguired

Status

in point mode

specify data

the X-

and Y-CONTROL

operations

(i.e.,

either 01 or 11*._fb§té is read'as:.
-

Data

Y Data

;_The Y Data is byte 1 and the X Data.is byte 2.A
'3.3flé Charaééer-Mode

two data bytes before REQ 1is set.
Character mode reguires

The

first déta byteh(the right half during an iOW instruction) is
used to plot the first vertical raster and the second is used to
plot the second vertical. raster.

3.6

Status*Registér;L'

The Status Register of the XY display consists of 2 bytes:
|

HIT

‘ MODE % LP - | LP = 1 REQ | BUSY| LOW - g ENABLE
|

ENABLE

rtad

]

9 o

11 >

- SPARE FOR

Y CONTROL

;

STORAGE

X CONTROL

BRIGHTNESS
|

2 0 7
T3
|
)
5
|
6
7
(Note? Although tfie-status Register is depicted in two bytes,
it may-be loaded, changed, read or tested with a single
command.
)

ENABLEfi The ENABLE bit.éonnécts the XY displéy to the interrupt
system. With this bit cleared, the display fiay in no way
affect the operation of the rest of the system,* ENABLE
is cleared‘by the power up/down response,

LOW:

by instruction

and from the console.
|
The LQW bit indicates which of two possible interrupt
addresses will be used by the processor when the display
interrupts.

In normal use,

LOW = @ indicates normal data

transfer on the multiplexor channel,

ferred each time REQ rises.

data being trans-

When the Byte Counter over-

*LP ENABLE provides the same function for the Light Pen.

flows,tLOW:éhdeEQ“é%é?%étf‘éausing an interrupt at the second
“interrupt add;eés.f‘_"~A

.if.é }ight pen'hii occuré and LP.ENABLE is set,.LOW is set and
an‘i%terrupt requested at the second address.

BUSY; | The BUSY bifi indicates that the aisplay is performing the

function indicated
by the other contrbl bits of the Status
Régister.

REQ:
|

‘i

it may_be-explicitly set by an IOC or an IOX

command or'implicifly bf an iOW command;

BUSY is cleared_

when the display completes its operation.

REQ is'éet by

the

display when

The

REQ bit

_If

ENABLE

BUSY is

cleared.

set whenever

also

set,

the

displays

interrupt

will

require

attention.

occur.

REQ

may

bé set or cleared_by explicit IOC or IOX commands and is
implicitly cleared during data

- channel

DIR:

transfers

on the multiplexor

(except for the last transfer which sets LOW) .

| Bit 11 of the Status Register is one indicatiné that the
display is an output device.

- not change.

It may be sensed but will

LP HIT: The LP HIT bit is.sefi if the Light Pen éenses light»ahd'
the LP ENABLE bit is set.

When LP HIT is set, LOW is set

and an interrupt requésted.' The program may tfien service

-the light-pen interrupt, clear LP HIT and LOW and dismis
‘;

LP ENABLE:

The LP ENABLE bit connects the Light Pen to the

interrupt.systemland enables the LP HIT bit.

MODE :

.There'ére twb béSié data moaes as cafitrolled by the state-

- of.thé mo&é-bit;t
MODE = 0; Point Mode

Data words sent to the dispiay; either by means

of IOW commands_§r through operation of the-multi—
plexor channel, are operated upon dgpending upon

the setting of.the X- and Y--Control bits of the
Stétus Regisfer.

In gefieral, a new X, Yposition

is producedin.the X-, Y-Axis registefs,.fihé'beam
is moved to

the

indicated pmsition on the display

facé and intensified according to the setting of.
thé intensity bits of the Sitatus Register.

‘;

)

Wheh

( this operation has been commleted, REQ igs set and
BUSY is cleared.

More data is éent to the display

depending upon whether or mot it is connected to
the

interrupt

system.

MODE = 1:; Character Mode

The display reads a_2—5yte @éta word and plots an
8 by 2 point raster.

For ewach bit in the data word.—

that ¢ontains é 1, the corresponding point of the
raster is intensified accor@ing to tfie_setting of

the intensity bits of the é&afigs Register. The

‘L

| L

- x- and Y-Control bits of the St;%us Register are
ignored.

After -the

entire 8 by 2 point raster has

10
bééfi7fiiotted;_the X-Axis register has been in-

cfemented by 2 and the Y-Axis register if left un-

e
e e g
o

disturbed.

When this operation has been completed,

REQ is set and Busy cleared.

More data is sent

to the diSpiay depen&ing upon Whethéf or not it

is confiécted to the interrupt system. A full
cha:actér may be plotted by displaying 6 byfes‘

or 3 words in éharécter mode to produce an 8x6
point raster.
Y +

Tfie‘data word is displayeé as:_'

Y + 6

Yy+5

Y + 4

'Y+3~.12‘

Y + 2

Y+

The original

ters were

contents

(x, y).

of the X -

and Y-Axis

The final contents are

regis-

(X + 2, Y)

BRIGHTNESS
=

_TWO'bits of the Status Register (6, 7) control the bright-ness of the points generated by operation of the display
control:

Q0 -

don't intensify

_léwest intensitf

medium intensity

highest

intensity

X—-CONTROL

Two bits of the Status Register (4,

5) control the loading

of the X-Axis register while in point mode
is

read

from the processor

and

the X-Axis

(MODE=O);
register

Data

up-

dated

according

to:

Clear X-Axis Register

Lnad XmAXis‘Registefnwith data byte

Leave-X—Axis Register unchanged

Add data byte to old contents of X-Axis
register

X-Axis

and

load

the

result

into

the

After the new X- and vY-Axis wvalues are-established,

the

‘beam is moved and intensified according
to the setting of
the intensity bits of the Status Register.

When this_op?

eration has been completed,

REQ is set and BUSY cleared.

Y-CONTROL

Two bits of the Status Register (2,

3) control the loading

of the Y-Axis register while in point mode

(MOfiE#Q).'

These

" bits are interpreted in a fashion identical to the inter’v

pretation

the

X-Control

bits.'

3.7 Programming Examples
Because

the

provide

3.7.1
Assume

inherent

comprehensive

Programmed
that

ordinates

flexible

the

programming

the XY display,
it

difficult

examoles:

Operation

subroutine

in real

time.

labeled

Each

call

SUBR calculates

SUBR places

new X,.Y co-

new value

X in accumulator. ACX and a new value of ¥in éccumulator ACY.

The program merely transfers these data p@ifits to the display

and recalls_thé subroutine:

.+ "DIS" IS THE DEVICE ADDRESS Of

I0C DIS,

[013430]

BEGIN:

SET

REQ;

HIGHEST

X-Y

THE XY DISPLAY

LOAD.,

;

BITS

SET

BRIGHTNESS

VALUE;

CONTROIL.

FIELDS

SET

CLE
ALL AR
OTHER

‘1. .

BAL SUBR
.

L
e

“~e

ACCUMULATOR AQY NOW

~ g

HALF

CONTAINS A 2 BYTE

ACY

WAIT

OF C (ACY)

DATA WORD

WAIT: TOT DIS, [fiooiqz.

IOW DIS,

STORE C(ACXIN
) LEFT

STC:ACX, gé*ACY f'%fi

CALIL SUBROUTINE

-y

GO:

TEST REQ FOR A ONE

;

WRITE ACY

BERO,

WAIT

TO DISPLAY

THIS CLEARS REQ AND

SETS BUSY
B

(Note:

The octal

written

3.7.2

;

GET ANOTHER POINT

constant in the IOC instruction could be

in binary as:

00010111

00011000.)

character Plotting Without Display File

’

Assume that there is a text string in memory that is terminated
by an EOT
of

character.

until

the

TEXT.

The

contents

by the main program.
the

contents

character

This

table

STOP
is

string

text

the

:
is

pointed

.
displayed

to by the

STOP become

the

C
face

set
:

The display service routine will then clear
and

stop

stored

displaying the text string.

in memory

starting

' MAIN PROGRAM STARTS DISPLAY

STOP

tube

non-zero

;

CLEAR STOP

SWITCH

location TARBLE.

This table consists of 3 entries.
(6 bytes) per symbol.

CLR

contents

STA AC, TEXT

SET POINTO
TER
TEXT
BUFFER

SET POINTER TO BEGINNING
OF

| STA AC, POINT

-8

roc p1s, [13]

awm

mem

mew

TEXT

STRING

; NOW - FORCE A LOW
~0

—

THE

INTERRUPT

soe

i TO STOP THE TEXT BEING DISPLAYED

¢ —1

TO CHANGE THE
,

—

m—

—

STA AC,

DISPLAY

TEXT

—

BEING

;

DISPLAYED

———

TEXT

INTERRUPT

SERVICE

1.DC

AC,

POINT

;

NO-GET

(127]

POINTER TO

ROUTINE

PENSER

cvp Ac,

BEGINNING OF TEXT STRING

TEST

cvp ac, [i5]
BZ

LOAD NEW

;

-y

DISINT: IOT DIS, [ 4% ] -

GETCHR:

WAIT TO STOP

HIT

SET-SERVICE

LIGHT-PEN

CHARACTER TO

STOP

DISPLAYED

TST

TEST FOR CARRIAGE RETURN

had]

STOP

BRANCH

;

COM

NO-TEST FOR LINE-FEED

YES

' }15

cwp ac, [04]

BRANCH
IF YES
NO-FORM

TABLE TO PLOT THTS

CHARACTER

DISINY
+

ADD START OF TABLE

1 ; LOAD

CHANNEL

BYTE

POINTER

LOAD

CHANNEL

BYTE

COUNTER

TO THE SIX BYTES IN

; 6 BYTES/SYMBOL

ADD AC + 1, [Q*TABLEQ}
STA AC

BYTE POINTER

moL ac, [6]

"TEST FOR EOT

-y

EQT

BRANCH IF YES

LDA AC,§~~6:§
DISINT

~
0

STA AC,

I0C DIS, 5?63;:5

: CLEAR LOW, SET REOQ

; SET MODE, SET BRIGHTNESS TO
;

PSD

i CLEAR REQ, SET ENABLE, CLEAR
MODE,

IOW DIS, ['Qf]

BY CLEARING X~-AXIS

Y-CONTROL

ICC DIS, [?002%}

’

BRIGHTNESS

-8

CR:

CARRIAGE~-RETURN

ENABLE

; DISMIS

SET

PROCESS

SET

WRITE

-9

PSD

HIGHEST,

DISMIS,

SET X-CONTROL

CLEAR

TO DON'T DISTURB
TO

DON'T

INTENSIFY

LOW

DISPLAY WILL

INTERRUPT WHEN DOKE

_16
PROCESS LINE-FEED BY ADDING 10 TO Y-AXTS

LF:

10C DIS,,£§402§}

MODE,

SET X-CONTROL TO DON'T
SET

ENABLE,

CLEAR

DISTURB,

SET

Y-CONTROL

CLEAR

ADD,

BRIGHTNESS

TO DON'T
¥

SET LOW
IOW DIS,

T -12;

PSD

RESETTING

DISMIS

TO Y

POINTER

LDA AC,

TEXT

STA AC,

POINT

TST

STOP

;

TEST

CONTIN

;

COM

STOP

;

STOP, CLEAR STOP AND

[}2023}

CLEAR

DISMIS

CLEAR

RFY,

MODE,

SET X-CONTROL

LOAD,

Y—CONTROL

IOW DIS,

XYINIT

IOC DIS,

ZERO—CONTINUE

~-e

PSD

MODE

-8

STOP

I0C DIS,

CONTIN:

;

-10

-8

EOT:

EOT

ADD

PROCESS

;

INTENSIFY

DISPLAY

SET

ENABLE,

TO
LOAD,

- BRIGHTNESS TO DON'T
INTENSIFY,

SET

LOW

WRITE INITIAL VALUES

~
e

XYINIT:

'DISMIS

\\..

PSD

INITIAL VALUE OF

CLEAR

(X,