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XX-6E2F3-AC

1969

8 pages

Original

1.0MB

Document:	FOCAL Pocket Card 19
Order Number:	XX-6E2F3-AC
Revision:
Pages:	8
Original Filename:	http://bitsavers.org/pdf/dec/pdp8/focal/FOCAL_Pocket_Card_1969.pdf

OCR Text

FOCAL

1'1~0.:1

FOCAL -~

lets you
tame a computer
LEARN TO USE A COMPUTER AS A SOPHISTICATED
CALCULATOR IN MINUTES
In a few minutes you can learn to use a full-scale
computer for sophisticated calculations. Without
learning to program, you can do table generation,
line plots, income taxes and even complex integral
calculations. FOCAL makes using the computer as
simple as using a desk calculator.

LEARN TO WRITE COMPUTER PROGRAMS IN A FEW
HOURS
In addition, FOCAL is very flexible . It is the ideal way
to begin learning to program a computer. FOCAL al lows the student or computer novice to learn to write
programs using straight-forward commands. FOCAL
allows him to check his program as he prepares i t adding, changing, or deleting. FOCAL will even tell
him where and how he went wrong if he makes an
error.
FOCAL programs will perform more complex calculations and repeat tedious problems easily. They will
instruct the computer to automatically make decisions and perform tasks based on user input. Plotting,
calculating, comparing, and formatting-easily written FOCAL programs can even monitor data and control experiments .
FOCAL is the most powerful language ava ilable for
small computers. Unlike any other language, FOCAL
features 14 functions, automatic error tracing, and
character editing. Even with all these features, FOCAL
leaves enough memory to solve 6-level simultaneous
equations.
* Formula CALculator trademark of Digital Equipment Corporation

NOW MULTI-USER FOCAL
Up to seven users can now run FOCAL simultaneously
on DIGITAL's PDP-8/ 1 computer. This makes available
an easy to operate system offering all the advantages
of FOCAL at the lowest per user cost ever. Schools,
engineering establishments, research labs, accounting
firms, or anyplace that used to feel a computer was
either too expensive or too complicated to program
can now have a dedicated computer at a fraction of
comparable costs.

AS A DESK CALCULATOR
Sitting at the teletype, simply type:

FOR ADDITION, SUBTRACTION,
MULTIPLICATION AND DIVISION
USER:

TYPE 25.38 + 12.479 -

FOCAL:

= +

4.629 • 4 . 7 I l.558

23 . 09•0

FOR SINE AND COSINE OF RADIANS
USER:

TYPE FSIN ( l.57 ) + FCOS( . 147)

FOCAL:

= +

i . 9092

FOR SQUARE ROOT
USER:

TYPE FSQT (2l. 56)

FOCAL:

= +

4 . 643 3

FOR EXPONENTIATION
USER:

TYPE 2512

FOCAL:

= +

625.llllllll

TO COMPUTE 300 FACTORIAL
USER:

SET A= l
FOR I :::: l,399; SET A= A•I
TYPE :i; . A

FOCAL:

= + ll.3ll6lJ51E+ 615

It's that easy, FOCAL prints out the answers in·
stantly-no programming, no complicated symbols,
no waiting. FOCAL leaves the user with a detailed
print out of all his work.

TO LEARN PROGRAMMING
Writing programs is an easy step by step process with
FOCAL. The user numbers each step or text line from
1.01 to 15.99. The computer then follows the num bered commands after it is given " GO" from the
user. That 's all, programs can be basic or compli cated . They can all do complex operations and be
stored on paper tape.

EUCLIDIAN ALGORITHM FOR GREATEST COMMON
DIVISOR
01.01 C EUCLIDIAN ALGORITHMl"'f0Ri'"GREATES1' COllllON DIVISOR-•,01.19 ASK •rHE
"l.2,e IF (0- NJ 1.3,1.3; SET S = N; SET N=D: SET D= S
£11.30 SET R= N-D•FITR (N/ D) :SET N= D;SETi"D =:- R; IF»• (R) 1.3,1.4,l.3
~l.40 TYPE •
GCD •,!M,N, ! !

'GO
THE TWO NUMBERS ARE :544
'GO
THE TWO NUMBERS ARE : 19

:5321

GCD =

:31

GCD =

TO CHANGE THE BASE OF A POSITIVE INTEGER
.01.04 ERASE
.01..05 ASK "CONVERT".D.• FROM BASE", Bl." TO BASE",B2. !
.01.10 SET I = l
.01.20 SET E= D/ ( lll!I J ; SET R2= FITR[!E + .01i1001 - FITR(E J) 'l0]
01.30 SET ANS = ANS +R2°B l t (I -1 ); SET R2 = R2'lll+!I-l)
01.40 SET D ~ FITR(D ) -FIT.R(R2); lF (D) 1.5. 1.5, 1.41
01.41 SET I = I + l; GOTO 1.20
.01.50 SET J = 20
01.60 SET I = ANS
01. 70 SET A= I/B2
01.80 SET I = FITR (AJ
01.90 IF (- A) 1.91, l.93
01.91 SET D(J )=( A- I ) 0 B2
01.92 SET J=J - 1; GOTO 1.7
01. 93 FOR L= J - 20,-1; TYPE :u . D(2 l +LJ
.01.94 TYPE

%. ! ! ! ; GOTO 1.04

USER TYPES •co• AND FOCAL ASKS A NUMBER. ITS PRESENT
BASE AND THE DES IRED NEW BASE.
•GO
CONVERT:? FROM BASE:l0 TO BASE:2
=+ l =+ l =+ l

THE SOLUTION OF THE INITIAL CONDITION PROBLEM DESCRIBED BY THE DIFFERENTIAL E9UATION
d 2X
dX
dt2 - KI (It
K2X = 0

FOR A SET OF GIVEN INITIAL VALUES
01..lll SET N= 5; SET C= 0
.01.1.0 ASK ?X2 Xl X Kl K2'? ! '?DT?

i?ll.20 SET X2 =- X•K2+KPX1
01.30 SET Xl ~ Xl + DT'X2
01.40 SET X= X+DT•Xl
.Ill. 50 SET C= C+l
.01.6.0 IF (C /N -F ITR (C /N ) I l.70,1.70,1.20
01. 70 DO 2; GOTO 1.20
02.05 IF (X- 40 ) 2.06; TYPE "OFF SCALE", !;QUIT
02 • .06 IF (-X-20) 2.10; TYPE "OFF - SCALE",! ;QUIT
lil'2.10 FOR I = 0,X +20: TYPE • •
02.2£1 TYPE • • •, !
USER TYPES •co• AND FOCAL ASKS FOR INITIAL VALUES
AND A DESIRED TIME INCREMENT "DT" THE OUTPUT I S A PLOT OF POSITION •x• VERSUS TIME "T" EACH POINT REPRESENTS FIVE TrME IN CRE>lENTS.

FOCAL OPERATIONS AND THEIR SYMBOLS
Exponentiation ( t) Multiplication (•) Division (/)
Addition ( +) Subtraction (-)
Up to two alphanumeric letters are accepted as vari able names 3fld all may be subscripted. Any of the
following parenthetical pairs may be used . ( ). [ ], and
nested to any depth . All commands except Write.
Modify, Quit, and Erase may be combined on the same
line if separated by a semicolon.

FOCAL'S FOURTEEN FUNCTIONS
FSQT( )
FABS( )
FSGN( )
FITR( )
FRAN( )
FE XP(
)
FSIN( )
FCOS( )
FATN( )
FLOG( )
FDIS( )
FADC( )
FNEW( )
FCOM( )

Square Root
Absolute Value
Sign Part of the Express ion
Integer Part of the Expression
A Noise Generator
Natural Base to the Power
Sine
Cosine
Arctan gent
Naperian Log
Scope Functions
Analog to Digital Input Function
User Function
Storage Function

FOCAL ERROR DIAGNOSTICS
Error messages are typed in the following format :
?nn .nn @ nn .nn
(error code @ line number)
Code

Meaning

?00.00
?01.00
?01.40
?01.78
?01.96
?01.:5
?01.;4
?02.32
?02.52
?02.79
?03.05

Manual Start given from console.
Interrupt from keyboard via control·C.
Illegal step or line number used .
Group number is too large.
Double periods found in a line number.
Line number is too large .
Group zero is an illegal line number.
Nonexistant Group referenced by ' DO'.
Nonexistant Line referenced by ' DO '.
Storage was filled by push -down -list.
Nonexistant line used after 'GOTO'
or ' IF'.
Illegal command used .
Left of "="in error in ' FOR ' or 'SET'.
Excess right terminators encountered .
Illegal terminator in ' FOR' command.
Missing argument in Display command .
Bad argument to ' MODIFY'.
Illegal use of function or number.
Storage is filled by variables.
Operator missing in expression or
double 'E'.
No operator used before parenthesis.
No argument given after function call.
Illegal function name or double operators .
Parenthesis do not match.
Bad argument in ' ERASE '.
Storage was filled by text.
Input buffer has overflowed.
Logarithm or zero requested.
Literal number is too large.
Exponent is too large or negative.
Division by zero requested.
Imaginary square roots required .
Illegal character, unavailable command,
or unavailable function used.

?03.28
?04.39
?04.52
?04.60
?04.:3
?05.48
?06.06
?06.54
?07.22
?07.38
?07 .: 9
?07.;6
?08.47
?09. 11
?10 .. :5
?11.35
?20.34
?23 .36
?26.99
?28.73
?30.05
?31. < 7

FOCAL COMMAND SUMMARY
Command Abbr.
TVPE

WRITE

£umplt of Form

Elplanatlon

TYPE FSQT(AL J + FSQT(B))

Evaluates expression , types out = ,

TYPE " TEXT STRING " !

and result in current output format
Types text. Use ! to generate carriage return line feed

WRITE ALL

Focal

WRITE 1
WRITE I.I

Focal types out all group I llnes
focal prints line 1.1

IF (X) 1.2, 1.3, 1.4 ;

Where X is Identifier or expression

prints

the

entire

indirect

Control Is transferred to the first, second , or th ird line number If (X) Is teu
than, equal to , or 1reater than 1ero respectively. If the semicolon Is encoun-

tered prematurely then the remainder ol the llne Is executed.
MOOIFY

MODIFY 1.15

Enables edJtln1 of characters

tlnel.15
The nut character typed becomes the search character. FOCAL wlll then
position itself after the search character ; then the user may :
1)

type new text, or

push form-feed to 10 to the next occurrence , or

push bell to chan1e the search character , or

push rubout to delete backwards, or

~ush left arrow to klll backwards, or

push carrla1e return to end the tine , or

push llne-feed to save the rest of the line .

QUIT

Returns control to user

RETURN

Terminates DO subroutines

SET

SET A= 5/ 8"SCALE(3)

Substitution statement

ASK

ASK ALPHA(I + 2• J)

Focal types a colon for each varl·
able: the user types a value to de·
fl !leeachvarlable .

COMM ENT

COMMENT

If a line begins with the letter C,
the remainder of the llne will be
Ignored.

CONTINUE

ERASE

c
DO 4.14

Execute line 4.14; return

00 4

Execute all group 4 lines , return
when group is upended or when a
RETURN is encountered .

DO ALL

Execute entire indirect t ~xt as a
subroutine.

ERASE

Erases the symbol table.

ERASE 2

Erases all group 2 lines .

ERASE 2. 1

Deletes line 2.1

ERASE ALL

Deletes all user text .

FOR

FOR I = x,y,z; TYPE I

The command string following the
semicolon is executed for each
value . x,y,z are constants, variables , or expressions. x = initial
value of I y = value added to I
until I is greater than z. y is as·
sumed = 1 if omitted.

Starts indirect program at lowest
numbered line number.

GOTO

GOTO 3.4

Starts indirect program at line 3.4

GO?

Traces indirect program
error is encountered .

*LINK

" Call Name"
START Te xt
ENO
Text
Variables
ENO
ENO
Free Core

xx xx
xx xx
xx xx
xx xx

until

Types octal bounds of indirect pro·
gram and transfers to 7600 to link
up with Disk Monitor or 8 lib Sys

FOCAL

a new conversational language
developed by Digital Equipment Corporation
for its PDP-8 family of small computers

APPLICATIONS

Computer aided instruction
Trigonometric problems
Numbers systems and base conversion
Geometric design
Factor analysis
Binomial expansions
Statistics
' Single or multi-function plotting
Linear algebra (simultaneous equations, matrices etc.)
Differential equations
Table generation
Simulation
Least squares fit
Eigenvalues
Digital filter design
Closed circuit traverse analysis
Measurement units conversion
Data monitoring
Compound interest
Stocks and bonds analysis
Decision theory
Budgeting
Scope and plotter output, and A/ D input
Many others

FOCAL
DIGITAL EQUIPMENT CORPORATION MaYl*d
Massac- TelePhOne 617 897-5111 •
ALABAMA. Huntsville • CALIFORNIA. An8lletm
Los Angeles and P9lo Atto • COLORADO
Denver • CONNECTICUT • DISTRICT
of COLUMBIA Wlsh1ng10n Colteoe Pllrk Md •
FLORIDA Qicoa • GEORGIA. Allanla • ILLINOIS
Chocago • MASSACHUSEns Cllmbndge and
Maynard • MICHIGAN Ann Arbor • MINNESOTA.
Mmneapolls • MISSOURI St lou19 • NEW
JERSEY.Pal'Sl-yandPl'i-ton • NEWMEXICO
Albu®erQUe • NEW YORK Cenlereach LI L "lbrk C.1y and Roc:hester • NORTH CAROLINA.

a_. Hill • OHIO Cleveland and Dayton •
PENNSYLVANIA. l'llll.iel""' and Plnsburllh •
TENNESSEE Knoxvolle • TEXAS. Olll8s and
Houston • UTAH Sllll Lake City • ~INGTON
Seattle • AUSTRALIA. llrilbmne Melbourne Perlll
and Sydney . CANADA. Edmonton Carleton " ' - on- and 'lbronto Ontano and
Montreal Quebec- • ENGLAND London
Mancheste• and Reed•no • FRANCE Paris •
GERMANY. Cologne and Mumdl • HOLLAND
The Hague • ITALY. Milan • JAl'lloN bkyo •
SWEDEN StockllQlrn • SWITZ£RLAND GIMva

l'lllllMllaU.S.A