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DEC-08-LBSMA-A-D

July 1973

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Document:	8K BASIC
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DEC-08-LBSMA-A-D

8K BASIC

For additional copies, order No. DEC-08-LBSMA-A-D
from Software Distribution Center, Digital Equipment
Corporation, Maynard, Mass.

digital equipment corporation · maynard. massachusetts

First Printing, July 1973

by Digital Equipment Corporation

The following are trademarks of Digital Equipment Corporation,
Maynard, Massachusetts:
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contents
Introduction ...... ............................... .... .............................

Numbers

Variables ............................................................................

Arithmetic Operations ........................................................
Priority of Arithmetic Operations ..................................
Parentheses ................................................................

3
4

Relational Operators ..........................................................

Immediate Mode .........................................'.......................
PRINT Command .... .... .. ..... ... .. . .. . ... ........... ... ... ....... .....
LET Command..............................................................

6
6

BASIC Statements ............................................................
Example Program ..........................................................
Statement Numbers ........................................................
Commenting the Program ............................................
REM ..........................................................................
Terminating the Program ..............................................
END ..........................................................................
STOP ........................................................................
The Arithmetic Statement ..............................................
LET ..........................................................................
Input/Output Statements ..............................................
READ and DATA ....................................................
RESTORE ................................................................
INPUT ......................................................................
PTR ..........................................................................
PRINT ......................................................................
LPT ............................................................................
PTP ............................................................................
TTY IN and TTY OUT ............................................

7
7
8

9
·9
9
9
10
10
10

11
11
12

14
14
15
19

20
20

Loops ........................................................................... .
FOR, NEXT, and STEP ........................................... .
Subscripted Variables ................................................... .
DIM ......................................................................... .

22
22
25
27

Transfer of Control Statements ................................... .
Unconditional Transfer-oGOTO ............................ ,.
Conditional Transfer-IF-THEN and IF-GOTO ..... .
Subroutines ................................................................... .
GOSUB and RETURN ........................................... .
Functions ..................................................................... .
Sign Function-SGN(x) ........................................... .
Integer Function-INT(x) ....................................... .
Random Number Function-RND(x) ................... .
TAB Function ........................................................... .
PUT and GET Functions ....................................... .
FNA Function ................................................ '" ., ... ,.. .

29
29

User-Defined Function-UUF ......................................... .
Coding Formats ........................................................... .
Floating-Point Format ................................................. .
Addressing ................................................................... .
Floating-Point Instruction Set ..................................... .
Writing the Program ................................................... .
Examples ..................................................................... .

43
43
44

Editing and Control Commands ..................................... .
Erasing Characters and Lines ....................................... .
SHIFT /0, RUBOUTS, and NO RUBOUTS ........ ..
Listing and Punching a Program ................................. .
LIST ........................................................................ ..
PTP and LPT ..........................................................
Reading a Program ..................................................... .
PTR ......................................................................... .
Running a Program ................................................... .
RUN ......................................................................... .
PTP and LPT ..........................................................
Stopping a Run ............ , .. " . . . " .. ... " . ." " " " " " " "
~

"""

"" "

"""" """""

30
30
30
34

35
35
36
37
39
42

45
47
48

53
53
53
55

55
55
56
56
56
56

57
57

CTRL/C ....................................................................
CTRL/O ..................................................................
Erasing a Program in Core ..........................................
SCR ..........................................................................
Loading and Operating Procedures ..................................
BASIC Comp~ler ................ ............ ...................... ........
User-Defined Function ..................................................

57
57
58
58
58
58
59

8K BASIC Error Messages ..............................................

8K BASIC Symbol Table ..................................................

Statement and Command Summaries ................................
Edit and Control Commands ........................................
BASIC Statements ........................................................

67
67
67

Appendix A
Appendix B ......................................................................

A-l
B-1

8K basic

INTRODUCTION
8K BASIC is an interactive programming language with a variety of applications. It is used in scientific and business environments
to solve both simple and complex mathematical problems with a
minimum of programming effort. It is used by educators and students as a problem-solving tool and as an aid to learning through
programmed instruction and simulation.
In many. respects the BASIC language is similar to other programming languages (such as FOCAL and FORTRAN), but
BASIC is aimed at facilitating communication between the user
and the computer. The BASIC user types in the computational
procedure as a series of numbered statements, making use of common English words and familiar mathematical notations. Because
of the small number of commands necessary and its easy applica. tion in solving problems, BASIC is one of the simplest computer
languages to learn. With experience, the user can add the advanced
techniques available in the language to perform more intricate
manipulations or express a problem more efficiently and concisely.
8K BASIC is an extended version of DEC's 4K BASIC,l but
has additional features and requires 8K of core. The user who has
no familiarity with the BASIC language may wish to refer to the
EduSystem Handbook for a background description of the language fundamentals, and for information pertaining to working
with BASIC at the computer.
The minimum system configuration for 8K BASIC is a PDP-8
1 4K

BASIC, or EduSystem 10, is the most fundamental BASIC in DEC's
series of EduSystems. This series is directed primarily for use in an educational environment. Information concerning the EduSystems may be obtained from DEC's PDP-8 Educational Marketing Department.

series computer with 8K of core memory. Supported options include a high-speed reader and punch, and an LP08 line printer.
New features provided by 8K BASIC include one and twodimensional subscripting, faster execution time, user-coded functions, use of the LP08 line printer and high-speed reader/punch,
and specification of input and output devices from any part of a
program.
Loading and operating instructions and a command summary
are included at the end of the manual.

NUMBERS
BASIC treats all numbers (real and integer) as decimal numbers
-that is, it accepts any number containing a decimal point, and
assumes a decimal point after an integer. The advantage of treating
all numbers as decimal numbers is that the programmer can use
any number or symbol in any mathematical expression without regard to its type.
In addition to integer and real formats, a third format is recognized and accepted by 8K BASIC and is used to express numbers
outside the range .01 <=x<=1 ,000,000. This format is called
exponential or E-type notation, and in this format, a number is
expressed as a decimal number times some power of 10. The
form is:
xxEn
where E represents "times IOta the power of"; thus the number
is read: "xx times IOta the power of n." For example:
23.4E2 = 23.4*10~ = 2340
Data may be input in anyone or all three of these forms. Results of computations are output as decimals if they are within the
range previously stated; otherwise, they are output in E format.
BASIC handles seven significant digits in normal operation and
input/ output, as illustrated below:
Value Typed In

Value Output By BASIC

.01
.0099
999999
1000000

.01
9.900000E-3
999999
1.000000E+6
2

BASIC automatically suppresses the printing of leading and trailing zeros in integer and decimal numbers, and, as can be seen
from the preceding examples, formats all exponential numbers in
the form:
(sign) x.xxxxxx E (+ or -) n
where x represents the number carried to six decimal places, E
stands for "times 10 to the power of," and n represents the exponential value. For example:
-3.470218E+8 is equal to -347,021,800
7.260000E-4 is equal to .000726
VARIABLES
A variable in BASIC is an algebraic symbol representing a
number, and is formed by a single letter or a letter followed by a
digit. For example:
Acceptable Variables
Unacceptable Variables
I

2C - a digit cannot begin
a variable
AB - two or more letters
cannot form a variable

X
The user may assign values to variables either by indicating the
values in a LET statement, or by inputting the values as data;
these operations are discussed further on in the manual.

ARITHMETIC OPERATIONS
BASIC performs addition, subtraction, multiplication, division
and exponentiation, as well as more complicated operations explained in detail later in the manual. The five operators used in
writing most formulas are:
Symbol
Meaning
Example
Operator

I
t

Addition
Subtraction
Multiplication
Division
Exponentiation
(Raise A to the
Bth power)
3

A+B
A-B
A*B

AlB
AtB

Priority of Arithmetic Operations
In any given mathematical formula, BASIC performs the arithmetic operations in the following order of evaluation:

1. Parentheses receive top priority. Any expression within
parentheses is evaluated before an unparenthesized expression.
2. In absence of parentheses, the order of priority is:
a. Exponentiation
b. Multiplication and Division (of equal priority)
c. Addition and Subtraction (of equal priority)
3. If either 1 or 2 above does not clearly designate the order of
priority, then the evaluation of expressions proceeds from
left to right.
The expression A tBtC is evaluated from left to right as follows:
1. AtB
2. (result of step 1) tC

== step 1
== answer

The expression A/B*C is also evaluated from left to right since
multiplication and division are of equal priority:

1. AlB
2. (result of step 1) *C

step 1

== answer

PARENTHESES
Parentheses may be used by the programmer to change the
order of priority (as listed in rule 2 above), as expressions within
parentheses are always evaluated first. Thus, by enclosing expressions appropriately, the programmer can control the order of evaluation. Parentheses may be nested, or enclosed by a second set (or
more) of parentheses. In this case, the expression within the inner- .
most parentheses is evaluated first, and then the next innermost,
and so on, until all have been evaluated.
Consider the following example:
A=7*«Bt2+L!)/X)

The order of priority is:
1. Bt2
2. (result of step 1) +4
3. (result of step 2) IX
4. (result of step 3) *7
4

step 1
step 2
step 3
A

Parentheses also prevent any confusion or doubt as to how the
expression is evaluated. For example:
A*Bf2/7+B/C+Df2

Both of these formulas will be executed in the same way. However, the inexperienced programmer or student may find that the
second is easier to understand.
Spaces may be used in a similar manner. Since the BASIC compiler ignores spaces, the two statements:
10 LET B = Df2 + 1
10LETB=Df2+1

are identical, but spaces in the first statement provide ease in
reading.

RELATIONAL OPERATORS
A program may require that two values be compared at some
point to discover their relation to one another. To accomplish this,
BASIC makes use of the following relational operators:

> greater than
> = greater than or

equal to
< less than
<= less than or
equal to

equal to
< > not equal to

Depending upon the result of the comparison, control of program
execution may be directed to another part of the program, or the
validity of the relationship may cause a value of 0 to 1 to be associated with a variable (that is, if a condition is true, a value of
1 is assigned; if a condition is not true, then the value of 0 is returned). Relational operators are used in conjunction with IF and
.LET statements, both of which are discussed in greater detail later
in the manual.
The meaning of the equal (=) sign should be clarified. In
algebraic notation, the formula X==X + 1 is meaningless. However,
in BASIC (and most computer languages), the equal sign desig:
nates replacement rather than equality. Thus, this formula is
actually translated: "add one to the current value of X and store
5

the new result back in the same variable X." Whatever value has
previously been assigned to X will be combined with the value 1.
An expression such as A=B+C instructs the computer to add the
values of Band C and store the result in a third variable A. The
variable A is not being evaluated in terms of any previously assigned value, but only in terms of Band C. Therefore, if A has
been assigned 'any value prior to its use in this statement, the old
value is lost; it is instead replaced by the value of B+C.
IMMEDIATE MODE
There are two commands available which allow BASIC to act
as a calculator-PRINT and LET. The user types in the algebraic
expression which is to be calculated, and BASIC types back the
result. This is called immediate mode since the user is not required
to write a detailed program to calculate expressions and equations,
but can use BASIC to produce results immediately.
PRINT Command
The PRINT command is of the form:
PRINT expression
and instructs BASIC to compute the value of the expression and
print it on the Teletype. The expression may be made up of any
decimal number, the arithmetic operators mentioned previously, and
the functions which are discussed further on in the manual. (These
may be used in conjunction with a string of text, as explained in the
section concerning the PRINT statement.) For example:
PRINT 1/8t8
5.960L!6L!E-08

LET Command
Values may be assigned to variables by use of the LET command as follows:
LET variable = expression
The computer does not type anything in response to this command, but merely stores the information. This information may
then be used in conjunction with a PRINT command to calculate
results. For example:
6

LET Pl=3.14159
PRINT Pl*4t2
50.26544

BASIC STATEMENTS
Example Program
The following example program is included at this point as an
illustration of the format of a BASIC program, the ease in running
it, and the type of output that may be produced. This program
and its results are for the most part self-explanatory. Following
sections cover the statements and commands used in BASIC programmIng.

10 REM - PROGRAM TO TAKE AVERAGE OF
15 REM - STUDENT GRADES AND CLASS GRADES
20 PRINT "HOW MANY STUDENTS, HOW MANY GRADES PER STUDENT";
30 INPUT A,B
40 LET 1=0
50 FOR J= I TO A-I
55 LET V=0
60 PRINT "STUDENT NUMBER =";J
75 PRINT "ENTER GRADES"
76 LET D=J
80 FOR K=D TO D+(B-l)
81 INPUT G
82 LET V=V+G
85 NEXT K
90 LET V=V/B
95 PRINT "AVERAGE GRADE =";V
96 PRINT
99 LET Q=Q+V
100 NEXT J
101 PRINT
102 PRINT
103 PRINT "CLASS AVERAGE =";Q/A
104 STOP
140 END

RUN
HOW MANY STUDENTS, HOW MANY GRADES PER STUDENT? 5,4
STUDENT NU~BER = 0
ENTER GRADES
?78
?86
?88
?74

AVERAGE GRADE

= 81.5

STUDENT NUMEER
ENTER GRADES
?59

= 1

?86
?7V'J

?87
AVERAGE GRADE

= 75.5

STUDENT NUMBER = 2
ENTER GRADES
?58
?64
?75
?8V'J

AVERAGE GRADE

= 69.25

STUDENT NUMBER = 3
ENTER GRADES
?88
? 92

?85
?79

AVERAGE GRADE

= 86

STUDENT NUMBER
ENTER GRADES

= 4

?60
?78

?85
?8V'J

AVERAGE GRADE

75.75

CLASS AVERAGE
READY.

Statement Numbers
An integer number is placed at the beginning of each line in a
BASIC program. BASIC executes the statements in a program in
numerically consecutive order, regardless of the order in which
they have been typed. A common practice is to number lines by

fives or tens, so that additional lines may be inserted in a program
without the necessity of renumbering lines already present.
Multiple statements may be placed on a single line by seperating each statement from the preceding statement with a backslash (SHIFT /L). For example:
10 A=S\B=.2\C=3\PRINT "ENTER DATA"

All of the statements in line 10 will be executed before BASIC continues to the next line. Only one statement number at the beginning
of the entire line is necessary. However, it should be remembered
that program control cannot be transferred to a statement within
a line, but only to the first statement of the line in which it is contained (see the section entitled Transfer of Control Statements).
Commenting the Program
REM
The REM or REMARK statement allows the programmer to
insert comments or remarks into a program without these comments affecting execution. The BASIC compiler ignores everything following REM. The form is:

(line number) REM (message)
In the Example Program, lines 10 and 15 are REMARK statements describing what the program does. It is often useful to put
the name of the program and information relating to. its use
at the beginning where it is available for future reference. Remarks
throughout the body of a long program will help later debugging
by explaining the purpose of each section of code within the
program.
Terminating the Program
END
The END statement (line 140 in the Example Program), if
present, must be the last statement of the entire program. The form
is:

(line number) END
This statement acts as a signal that the entire program has been
executed. Use of the statement is optional. However, if the program contains an END statement, after execution, variables and
9

arrays are left in an undefined state, thereby losing any values they
have been assigned during execution.
STOP
The STOP statement is used synonymously with the END statement to terminate execution, but while END occurs only once at
the end of ~ program, STOP may occur any number of times. The
format of the STOP statement is:
(line number) STOP
This statement signals that execution is to be terminated at that
point in the program where it is encountered.
The Arithmetic Statement
LET
The Arithmetic (LET) statement is probably the most commonly used BASIC statement and is used whenever a value is to
be assigned to a variable. It is of the form:

(line number) (LET) x = expression
'where x represents a variable, and the expression is either a number, another variable, or an arithmetic expression. The word 'LET'
is optional; thus the following statements are treated the same:
100 LET A=AfR+10

110 LET C=F/G

100 A=AtF3+10

110 C=F/G

As mentioned earlier, relational operators may be used in a LET
statement to assign a value of 0 (if false) or I (if true) to a
variable depending upon the validity of a relationship. For example:
100
110
120
1 30
140
150

A=1\B=2
C=A=B
D=A>B
E=A<>B
PRINT C.,D.,E
END

Translated, this actually means "let C= 1 if A=B (0 otherwise);
let D== 1 if A> B (0 otherwise)" and so on. Thus, the values of C,
D, and E are printed as follows:
10

RUN

READY.

There is no limit to the number of relationships that may be tested
in the statement.
Input/ Output Statements
Input/Output statements allow the user to bring data into a
program and output results or data at any time during execution.
The Teletype keyboard, low or high-speed reader/punch, and
LP08 line printer are all available as I/O devices in 8K BASIC.
Statements which control their use are described next.
READ AND DATA
READ and DATA statements are used to input data into a program. One statement is never used without the other. The form of
the READ statement is:
(line number) READ x I, x2, ... xn
where xl through xn represent variable names. For example:
10 READ A"B"C

A, B, and C are variables to which values will be assigned. Variables in a READ statement must be separated by commas. READ
statements are generally placed at the beginning of a program, but
must at least logically occur before that point in the program
where the value is required for some computation.
Values which will be assigned to the variables in a READ statement are supplied in a DATA statement of the form:
(line number) DATA xl, x2, ... xn
where x 1 through xn represent values. The values must be separated by commas and occur in the same order as the variables
which are listed in the corresponding READ statement. A DATA
statement appropriate for the preceding READ statement is:
70 DATA 1,2,3

Thus, at execution time A=I, B==2, and C=3.
The DATA statement is usually placed at the end of a program
(before the END statement) where it is easily accessible to the
programmer should he wish to change the values.
A READ statement may have more or fewer variables than
there are values in any one DATA statement. The READ statement causes BASIC to search all available DATA statements in
the order of their line numbers until values are found for each
variable in the READ. A second READ statement will begin reading values where the first stopped. If at some point in the program
an attempt is made to read data which is not present or if the data
is not separated by commas, BASIC will stop and print the following message at the console:
DATA ERROR AT LINE XXXX

where XXXX indicates the line which caused the error.
RESTORE
If it should become necessary to use the same data more than
once in a program, the RESTORE statement will make it possible
to recycle through the DATA statements beginning with the lowest
numbered DATA statement. The RESTORE statement is of the
form:
(line number) RESTORE
An example of its use follows:
15 READ B."C."D

55 RESTORE
60

100

READ E."F."G

END

The READ statements in lines 15 and 60 will both read the first
three data values provided in line 80. (If the RESTORE statement

had not been inserted before line 60, then the second READ would
pick up data in line 80 starting with the fourth value.)
The programmer may use the same variable names the second
time through the data, or not, as he chooses, since the values are
being read as though for the first time. In order to skip unwanted
values, the programmer may insert replacement, or dummy, variables. Consider:

1 REM - PROGRAM TO ILLUSTRATE USE OF RESTORE
20 READ N
25 PRINT "VA.LUES OF X ARE:"
30 FOR 1=1 TO N
40 READ X
50 PRINT X,
60 NEXT I
70 RESTORE
185 PRINT
190 PRINT "SECOND LIST OF X VALUES"
200 PRINT "FOLLOWING RESTORE STATEMENT:"
210 FOR 1=1 TO N
220 READ X
230 PRINT X,
2LJ0 NEXT I
250 DATA Lj, 1,2
251 DATA 3,LJ
300 END

RUN
VALUES OF X ARE:
1

SECOND LIST OF X VALUES
FOLLOWING RESTORE STATEMENT:
2
LJ
1
READY.

The second time the data values are read, the first X picks up
the value originally assigned to N in line 20, and as a result, BASIC
prints:

To circumvent this, the programmer could insert a dummy variable
which would pick up and store the first value, but would not be
represented in the PRINT statement, in which case the output
would be the same each time through the list.
INPUT
The INPUT statement is used when data is to be supplied by
the user from the Teletype keyboard while a program is executing,
and is of the form:
(line number) INPUT xl, x2, ... xn
where xl through xn represent variable names. For example:
25 INPUT A,B,C

This statement will cause the program to pause during execution,
print a question mark on the Teletype console, and wait for the
user to type in three numerical values. The user must separate the
values by commas; they are entered into the computer by his pressing the RETURN key at the end of the list.
If the user does not insert enough values to satisfy the INPUT
statement, BASIC prints another question mark and waits for more
values to be input. When the correct number has been entered,
execution continues. If two many values are input, BASIC ignores
those in excess of the required number. The values are entered
when the user types the RETURN key.
PTR
A PTR statement is used when data is to be input from the highspeed paper tape reader. The format of the data on the paper tape
must be the same as it would be if it were input from the Teletype
keyboard. If more than one value is to be input at a time, the
values must be separated by commas. The tape must be positioned
in the reader before it is called by the program; while it is reading,
there is no echo (type out) on the Teletype. The for~ is:
(line number) PTR
The PTR statement is most useful for inputting large amounts of
data in conjunction with the INPUT command. The following
program accepts 20 data values from the high-speed reader, prints
a heading, the value input, and its sine on the Teletype:
14

50 PTR
60 PRINT "SINE TABLE"
100 FOR J=1 TO 20
110 INPUT A
120 LET B=SINCA)
130 PRINT A.1B
140 NEXT J
1 50 END

RUN
SINE TABLE
-.97
-.911
-.872
-.723
-.719
-.61
-.502
-.346
-.33
-.283
-.175
-.155
- .02
.03
.093
.127
• 13
.42
.529
.632

-.8248857
-.79011 71
-.7656171
-.6616371
-.6586325
-.5728675
-.4811798
-.3391376
-.324043
-.2792376
-.1741081
-. 1543801
-.01999867
.0299955
.092866
.1266589
.1296341
.4077605
.5046703
.5907596

READY.

PRINT
The PRINT statement is used to output results of computations,
comments, values of variables, or plot points of a graph on the
Teletype. The format is:
(line number) PRINT expression
When used without an expression, a blank line will be output on
the Teletype. For more complicated formats, the type of expression
and the type of format control characters following the word
PRINT determines which formats will be created.
In order to have the computer print out the results of a computation, or the value of a variable at any point in the program, the
15

user types the line number, PRINT, and the variable name(s)
separated by a format control character, in this case, commas:
5 A=1()\B=5\C=4
10 PRINT A~C+R~SQR(A)

In BASIC, ·a Teletype line is formatted into five fixed columns
(called print zones) of 14 spaces each. In the above example, the
values of A, C+B, and the square root of A will be printed in the
first three of these zones as follows:
RUN
16

READY.

A statement such as:
5 A=2.3\R=21\C=156.75\D=1.134\E=23.4
10 PRINT A~B,C,D,E

will cause the values of the variables to be printed in the same
format using all five columns:
RUN

2.3

156.75

1.134

23.4

READY.

When more than five variables are listed in the PRINT statement,
the sixth value begins a new line of output.
The PRINT statement may also be used to output a message or
line of text. The desired message is simply placed in quotation
marks in the PRINT statement as follows:
10 PRINT "THIS IS A TEST"

When line lOis encountered during execution, the following will
be printed:
THIS IS A TEST

A message may be combined with the result of a calculation or a
variable as follows:

80 PRINT "AMOUNT PER PAYMENT ="R

Assuming R=344.9617, when line 80 is encountered during execution, this will be output as:
RUN
AMOUNT PER PAYMENT = 344.9617
READY.

It is not necessary to use the standard five zone format for output. The control character semicolon· ( ;) causes the text or data
to be output immediately after the last character printed (separated by one space.) If neither a comma nor a semicolon is used,
BASIC assumes a semicolon. Thus both of the following:
80 PRINT "AMOUNT PER PAYMENT ="R
80 PRINT "AMOUNT PER PAYMENT =";R

will result in:
AMOUNT PER PAYMENT = 344.9617

The PRINT statement can also cause a constant to be printed on
the console. (This is similar to the PRINT command used in Immediate Mode.) For example:
10 PRINT 1.234,SQR(10014)

will cause the following to be output at execution time:
1.234

100.07

Any algebraic expression in a PRINT statement will be evaluated
using the current value of the variables. Numbers will be printed
according to the format previously specified.
The following example program illustrates the use of the control
characters 2 in PRINT statements:
2 The user may wish to refer to the section entitled Functions for information pertaining to three functions available for additional character
control-TAB, PUT, and GET.

1121
2121
3121
4121
5121
6121

READ A,B,C
PRINT A,B,C,At2,Bt2,Ct2
PRINT
PRINT A;B;C;AT2;Bt2;Ct2
DATA 4,5,6
END

RUN

36
4

READY.

As this example illustrates, if a number should be too long to be
printed on the end of a single line, BASIC automatically moves the
entire number to the beginning of the next line.
Another use of the PRINT statement is to combine it with an
INPUT statement so as to identify the data expected to be entered.
As an example, consider the following program:
10 REM - PROGRAM TO COMPUTE INTEREST PAYMENTS
20 PRINT "INTEREST IN PERCENT";
25 INPUT J
26 LET J=J/100
30 PRINT "AMOUNT OF LOAN" ;
35 INPUT A
40 PRINT "NUMBER OF YEARS";
45 INPUT N
50 PRINT "NUMBER OF PAYMENTS PER YEAR";
55 INPUT M
60 LET N=N*M
65 LET I=J/M
70 LET B=!+I
75 LET R=A*I/(1-1/BfN)
78 PRINT
80 PR INT "AMOUNT PER PAYMENT ="; R
85 PRINT "TOTAL INTEREST
=";R*N-A
88 PRINT
90 LET B=A
95 PRINT " INTEREST
APP TO PRIN
BALANCE"
100 LET L=B* I
110 LET P=R-L
120 LET B=B-P
130 PRINT L.,P.,B
140 IF B>=RGC TO 100
150 PRINT B*I.,R-B*I
160 PRINT "LAST PAYMENT ="B*I+B
200 END

RUN

INTEREST IN PERCENT?9
AMOUNT OF LOAN?2500
NUMEER OF YEARS?2
NUMBER OF PAYMENTS PER YEAR?4
AMOUNT PER PAYMENT = 344.9617
TOTAL INTEREST
= 259.6932
INTEREST
56.25
49.75399
43.11182
36.32019
29.37576
22.27508
15.01463
7.590824
LAST PAYMENT

APP TO PR IN
288.7117
295.2077
301.8498
308.6415
315.5859
322.6866
329.947
337.3708
= 344.9608

BALANCE
2211.288
1916.081
1614.231
1305.589
990.0035
667.317
337.3699

READY.

As can be noticed in this example, the question mark is grammatically useful in a program in which several values are to be
input by allowing the programmer to formulate a verbal question
which the input value will answer.
LPT
The LPT statement is used to generate output on the LP08 line
printer, and is of the form:
(line number) LPT
By inserting this statement anywhere in a program, all subsequent
output, with the exception of error messages, will be printed on the
line printer. The LPT statement is particularly advantageous for
outputting large amounts of calculated data, as can be seen from
this and following examples:
100
110
120
130
140

LPT
FOR F=30 TO 60 STEP 3
PRINT FJlFf2
NEXT F
END

q~~

10bq
12q&

1521
17b4

21iJ25

2304
2b01
2qlb

32"Q
30~H"

When the END statement is encountered in the program, the
output device is reset to the Teletype.
PTP
The high-speed paper tape punch is also available as an output
device in 8K BASIC, permitting users to save data or output files
quickly on paper tape. When the statement is encountered, all
output is diverted from the Teletype to the high-speed punch. Control automatically returns to the Teletype when the END statement
is encountered. The form is:
(line number) PTP
By substituting this statement in line 100 of the previous program,
all output, with the exception of error messages, will be sent to the
high-speed paper tape punch instead of the line printer.
TTY IN AND TTY OUT
The Teletype may be placed under program control so that,
during execution of a program, 110 may be obtained or sent alternately between any available device. By issuing the statement:
(line number) TTY IN
control of input is returned to the Teletype if it has been previously
set to another device. Similarly, the statement:
(line number) TTY OUT
returns output control to the Teletype.
20

The following program makes use of most all the available I/O
devices. The output, with the exception of paper tape, is also
included.
100 LPT
110 PRINT "FIRST DEGREE EQUATION CALCULATION"
120 TTY IN
130 TTY OUT
135 PRINT "TYPE Xl Y1 THEN X2 Y2"
140 INPUT X1,Y1,X2,Y2
150 X=X2-X1
160 Y=Y2-Y1
170 M=Y/X
180 B=Y2-M*X2
190 IF B> =0 THEN 300
200 PRINT "Y="M"X"B
210 LPT
220 PRINT "Y="M"X"B
230 GO TO 400
300 PRINT "Y="M"X+"B
310 LPT
320 PRINT "Y="M"X+"B
400 FOR Y=0 TO 10 STEP 2
410 FOR X=0 TO 10 STEP .5
420 LET T=M*X+B-Y
430 IF T<>0 THEN 480
440 PRINT X,Y
450 PTP
460 PRINT X, Y
470 LPT
480 NEXT X
490 NEXT Y
500 END

RUN
TYPE Xl Y1 THEN X2 Y2
1-3,-4,-1,0
Y= 2 X+ 2
READY.

The line printer output is the following:
FIRST

DEG~~E

CALCULATIO~

va 2 x+ 2

"
1
2
3
4

NOTE
The Teletype low-speed reader and punch
may be used as I/O devices at any time. No
special statement is required. To read in data
from the low-speed reader, position the tape
over the sprocket wheel and set the reader to
START when input is required. The tape
will begin reading in. To punch a tape, set
the low-speed punch to ON and all ouput
will be punched on the low-speed punch.
Using the low-speed I/O devices is, in
effect, the same as using the Teletype keyboard. Characters will be typed on the Teletype keyboard as tapes are being read in or
punched.
Loops
FOR, NEXT, AND STEP
FOR and NEXT statements define the beginning and end of a
loop. A loop is a set of instructions which are repeated over and
over again, each time being modified in some way until a terminal
condition is reached. The FOR statement is of the form:
(line number) FOR v=xl TO x2 STEP x3
where v represents a variable name, and xl, x2, and x3 all represent formulas (a formula in this case means a numerical value,
variable name, or mathematical expression). v is termed the index,
xl the initial value, x2 the terminal value, and x3 the incremental
value. For example:
15 FOR K=2 TO 20 STEP 2

This means that the loop will be repeated as long as K is less than
or equal to 20. Each time through the loop, K is incremented by 2,
so the loop will be repeated a total of 10 times.
A variable used as an index in a FOR statement must not be
subscripted, although a common use of loops is to deal with subscripted variables, using the value of the index as the subscript of
22

a previously defined variable (this is illustrated in the section concerning Subscripted Variables).
The NEXT statement is of the form:
(line number) NEXT
and signals the end of the loop. When execution of the loop reaches
the NEXT statement, the computer adds the STEP value to the
index and checks to see if the index is less than or equal to the
terminal value. If so, the loop is executed again. If the value of
the index exceeds the terminal value, control falls through the loop
to the following statement, with the value of the index equaling the
value it was assigned the final time through the 100p. 3
If the STEP value is omitted, a value of + 1 is assumed. Since
+ 1 is the usual STEP value, that portion of the statement is frequently omitted. The STEP value may also be a negative number.
The following example illustrates the use of loops. This loop is
executed 10 times: the value of I is 10 when control leaves the
loop. + 1 is the assumed STEP value.
1 0 FOR I = 1 TO 10
20 NEXT I
30 PRINT I
40 END

RUN
10
READY.

If line 10 had been:
10 F OR

I = 10

TO 1 STEP

- 1

the value printed by the computer would be 1.
As indicated earlier, the numbers used in the FOR statement
3 The user should note that this method of handling loops varies among
different versions of BASIC.

are formulas; these formulas are evaluated upon first encountering
the loop. While the index, initial, terminal and STEP values may
be changed within the loop, the value assigned to the initial formula
remains as originally defined until the terminal condition is reached.
To illustrate this point, consider the last example program. The
value of I (in line 10) can be successfully changed as follows:

10 FOR 1=1 TO 10
15 LET 1=10
20 NEXT 1

The loop will only be executed once since the value 10 has been
reached by the variable I and the terminal condition is satisfied.
If the value of the counter variable is originally set equal to the
terminal value, the loop will execute once, regardless of the STEP
value. If the starting value is beyond the terminal value, the loop
will also execute only once.
It is possible to exit from a FOR-NEXT loop without the index
reaching the terminal value. (This is known as a conditional transfer and is explained in the section entitled Transfer of Control
Statements.) Control may only transfer into a loop which has been
left earlier without being completed, ensuring that the terminal
and STEP values are assigned.
Nesting Loops
It is often useful to have one or more loops within a loop. This
technique is called nesting, and is allowed as long as the field of
one loop (the numbered lines from the FOR statement to the corresponding NEXT statement, inclusive) does not cross the field of
another loop. A diagram is the best way to illustrate acceptable
nesting procedures:

ACCEPTABLE NESTING
TECHNIQUES

UNACCEPTABLE NESTING
TECHNIQUES

Two Level Nesting
FOR
FOR
[
NEXT
FOR
[
NEXT
NEXT

FOR

FOR
NEXT
NEXT

Three Level Nesting
FOR
FOR
FOR
[
NEXT
FOR
[
NEXT
NEXT
NEXT

FOR
FOR
FOR
[
NEXT
FOR
NEXT
NEXT
NEXT

A maximum of eight (8) levels of nesting is permitted. Exceeding
that limit will result in the error message:
FOR ERROR AT LINE XXX X

where XXXX is the number of the line in which the error occurred.
Subscripted Variables
In addition to single variable names, BASIC accepts another
class of variables called subscripted variables. Subscripted variables
provide the programmer with additional computing capabilities for
handling lists, tables, matrices, or any set of related variables.
Variables are allowed one or two subscripts. A siI}gle letter forms
the name of the variable; this is followed by one or two integers
in parentheses and separated by commas, indicating the place of
that variable in the list. Up to 26 arrays are possible in any program (corresponding to the letters of the alphabet), subject only
to the amount of core space available for data storage. For example, a list might be described as A (I) where I goes from 1 to 5,
as follows:
25

This allows the programmer to reference each of the five elements
in the list A. A two dimensional matrix A(I, J) can be defined in a
similar manner, but the subscripted variable A can only be used
once (i.e., A(I) and A(I,J) cannot be used in the same program).
It is possible however, to use the same variable name as both a
subscripted and an unsubscripted variable. Both A and A(I) are
valid variable names and can be used in the same program.
Subscripted variables allow data to be input quickly and easily,
as illustrated in the following program (the index of the FOR statement in line~ 20, 42, and 44 is used as the subscript) :
10 REM - PROGRAM DEMONSTRATING READING
11 REM - OF SUBSCRIPTED VARIABLES
15 DIM A(5),BC2,3)
18 PRINT "ACI) WHERE A=1 TO 5;"
20 FOR 1=1 TO 5
25 READ AC I)
30 PR INT A CI ) ;
35 NEXT I
38 PRINT
39 PRINT
40 PRINT "BCI,J) WHERE 1=1 TO 2:"
41 PRINT"
AND J=1 TO 3:"
42 FOR 1=1 TO 2
43 PRINT
44 FOR J=1 TO 3
4 8 READ B CI , J)
50 PRINT BCI,J);
55 NEXT J
56 NEXT I
60 DATA 1,2,3,4,5,6,7,8
61 DATA 8,7,6,5,4,3,2,1
65 END
RUN

ACI) WHERE A=1 TO 5;
234 5
BCI,J) WHERE 1=1 TO 2:
AND J=1 TO 3:
6 7 8
8 7 6
READY.

DIM
From the preceding example, it can be seen that the use of subscripts requires a dimension (DIM) statement to define the maximum number of elements in the array. The DIM statement is of
the form:

(line number) DIM VI (nl), v~ (n:,!, m:.!)
where v., indicates an array variable name and nand m are integer
numbers indicating the largest subscript value required during the
program. For example:
15 DIM

A(6~10)

The first element of every array is automatically assumed to have
a subscript of zero. Dimensioning A (6, 10) sets up room for an
array with 7 rows and 11 columns. This matrix can be thought of
as existing in the following form:
Ao,lo
Al,ll)

A 2 ,lo

AG,o

A G,1

and is illustrated in the following program:

10
15
20
22
25
28
30
35
40
45
50

REM - MATRIX CHECK PROGRAM
DIM A(6.110 )
FOR 1=0 TO 6
LET A(I.10)=I
FOR J=0 TO 10
LET A(0.1J)=J
PR INT A ( 1.1 J) ;
NEXT J
PRINT
NEXT I
END

RUN
1
0
1
0
2
0
3 0
4
0
5
0
6
0

2
0
0
0
0
0
0

3
0
0
0
0
0
0

4
0
0
0
0
0
0

5
0
0
0
0
0
0

6
0
0
0
0
0
0

7
0
0
0
0
0
0

0
0
0
0
0
0

10
0
0
0
0
0
0

READY.

Notice that a variable assumes a value of zero until another value
has been assigned. If the user wishes to conserve core space by not
making use of the extra variables set up within the array, he should
set his DIM statement to one less than necessary, DIM A(5,9).
This results in a 6 by 10 array which may then be referenced beginning with the A (0, 0) element.
More than one array can be defined in a single DIM statement:
10 DIM A(20).1 B(4.17)

This dimensions both the list A and the matrix B.
A number must be used to define the maximum size of the array.
A variable inside the parentheses is not acceptable and will result
in an error message by BASIC at run time. The amount of user
core not filled by the program will determine the amount of data
the computer can accept as input to the program at anyone time.
In some programs a TOO-BIG ERROR may occur, indicating
that core will not hold an array of the size requested. In that event,
28

the user should change his program to process part of the data in
one run and the rest later.
Transfer of Control Statements
Certain control statements cause the execution of a program to
jump to a different line either unconditionally or depending upon
some condition within the program. Looping is one method of
jumping to a designated point until a condition is met. The following statements give the programmer added capabilities in this area.
UNCONDITIONAL TRANSFER-GOTO
The GOTO (or GO TO) statement is an unconditional statement used to direct program control either forward or back in a
program. The form of the GOTO statement is:
(line number) GOTO n
where n represents a statement number. When the logic of the
program reaches the GOTO statement, the statement(s) immediately following will not be executed; instead execution is transferred
to the statement beginning with the line number indicated.
The following program never ends; it does a READ, prints
something, and jumps back to the READ via a GOTO statement.
It attempts to do this over and over until it runs out of data, which
is sometimes an acceptable, though not advisable, way to end a
program.
10 REM - PROGRAM ENDING WITH ERROR
11 REM - MESSAGE WHEN OUT OF DATA
20 READ X
25 PRINT "X="X,"Xt2="Xt2
30 GO TO 20
35 DATA 1,5,10,15,20,25
40 END

RUN
X= 1
X= 5
X= 10
X= 15
X= 20
X= 25

Xt2=
Xt2=
Xt2=
Xf2=
Xf2=
Xt2=

1
25
100
225
400
625

DATA ERROR AT LINE 20

CONDITIONAL TRANSFER-IF-THEN AND IF-GOTO
If a program requires that two values be compared at some
point, control of program execution may be directed to different
procedures depending upon the result of the comparison. In computing, values are logically tested to see whether they are equal,
greater than, less than another value, or possibly a combination of
the three. This is accomplished by use of the relational operators
discussed earlier.
IF-THEN and IF-GOTO statements allow the programmer to
test the relationship between two formulas (variables, numbers, or
expressions). Providing the relationship described in the IF statement is true at the point it is tested, control will transfer to the
line number specified, or perform the indicated operation. The
statements are of the form:

(line number) IF vI <relation> v2 {~~~~}x or expression
where v 1 and v2 represent variable names or expressions, x represents a line number, and expression represents an operation to be
performed. The use of either THEN or GOTO is acceptable.
The following two examples are equivalent (the value of the
variable A is changed or remains the same depending upon A's
relation to B) :

100 IF A>B THEN 120
110 A=AfB-1
120 C=A/D

100 IF A<=B THEN A=AfB-1
110 C=A/D

Subroutines
GOSUB AND RETURN
A subroutine is a section of code performing some operation
that is required at more than one point in the program. Often a
30

complicated I/O operation for a volume of data, a mathematical
evaluation which is too complex for a user-defined function, or any
number of other processes may best be performed in a subroutine.
Subroutines are generally placed physically at the end of a program, usually before DATA statements, if any, and always before
the END statement. Two statements are used exclusively in
BASIC to handle subroutines; these are the GOSUB and RETURN
statements.
A program begins execution and continues until it encounters a
GOSUB statement of the form:
(line number) GOSUB x
where x represents the first line number of the subroutine. Control
then transfers to that line. For example:

50 GOSUP 200

When program execution reaches line 50, control transfers to line
200; the subroutine ~s processed until execution encounters a RETURN statement of the form:
(line number) RETURN
which causes control to return to the statement following the
GOSUB statement. Before transferring to the subroutine, BASIC
internally records the next statement to be processed after the
GOSUB statement; thus the RETURN statement is a signal to
transfer control to this statement. In this way, no matter how many
different subroutines are called, or how many times they are used,
BASIC always knows where to go next.
The following program demonstrates a simple subroutine:

1 REM - THIS PROGRAM ILLUSTRATES GOSUB AND RETURN
10 DEF FNACX)=ABSCINTCX»
20 INPUT A."B."C
30 GOSUB 100
40 LET A=FNACA)
50 LET B=FNA CB)
60 LET C=FNA CC)
70 PRINT
80 GOSUB 100
90 STOP
100 REM - THIS SUBROUTINE PRINTS OUT THE SOLUTIONS
110 REM - OF THE EQUATION: ACXt2) + BCX) + C = 0
120 PRINT '!THE EQUATION IS
"A"*Xt2 + "B"*X + tIC
130 LET D=B*B-4*A*C
140 IF D<>0 THEN 170
150 PRINT "ONLY. ONE SOLUTION ••• X ="-B/C2*A)
160 RETURN
170 IF D<0 THEN 20~
180 PRINT "TWO SOLUTIONS ••• X =";
185 PRINT C-B+SQRCD»/C2*A)"AND X ="C-B-SQRCD»/C2*A)
190 RETURN
200 PRINT "IMAGINARY SOLUTIONS ••• X =; C";
2 0 5 P R IN T - B / C2 * A ) " ." " S QR ( - D ) / ( 2 * A ) " ) AN DC" ;
207 PRINT -B/C2*A)".,,"-SQR(-D)/C2*A)")"
210 RETURN
900 END

RUN
?1,.5.,,-.5
THE EQUATION IS
1 *Xt2
+
.5 *X
TWO SOLUTIONS ••• X
.5 A~D X =-1

.+ -.5

THE EQUATION IS
1 *Xt2
+
0 *x +
IMAGINARY SOLUTIONS ••• X = ( 0 , 1 )

1
AND~

C 0 .,,-1

)

READY.

Line 100 begins the subroutine. There are several places in which
control may return to the main program, depending upon a certain.
condition being satisfied. The subroutine is executed from line 30
and again from line 80. When control returns to line 90, the program encounters the STOP statement and execution is terminated.
It is important to remember that subroutines should generally
be kept distinct from the main program. The last statement in the
main program should be a STOP or GOTO statement, and subroutines are normally placed following this statement.
32

More than one subroutine may be used in a single program, in
which case these can be placed one after another at the end of the
program (in line number sequence). A useful practice is to assign
distinctive line numbers to subroutines. For example, if the main
program is numbered with line numbers up to 199, 200 and 300
could be used as the first numbers of two subroutines.

Nesting Subroutines
Nesting of subroutines occurs when OOe subroutine calls another subroutine. If a RETURN statement is encountered during
execution of a subroutine, control returns to the statement following the GOSUB which called it. From this point, it is possible to
transfer to the beginning or any part of a subroutine, even back to
the calling subroutine. Multiple entry points and RETURN statements make subroutines more versatile.
The maximum level of GOSUB nesting is about thirty-three (33)
levels, which should prove more than adequate for all normal uses.
Exceeding this limit will result in the message:

GOSUB ERROR AT LINE XXXX

where XXXX represents the line number where the error occurred.
An example of GOSUB nesting follows (execution has been stopped
by typing a CTRLjC, as the program would otherwise continue in
an infinite loop; see Stopping a Run.)

10 ijEM FACTORIAL PROGRAM USING GOSUB TO

15 REM RECURSIVELY GOMPUTE THE FACTORS
INPUT N
50 IF N> 20 THE~ 120
60 X= 1

70 K=l

80 GOSUB 200
90 PRINT "FACTORIAL"W" ="X
110 GO TO 40
120 PRINT "MUST BE 20
130 GO TO 40

OR LESS"

200 X='X*K
210 K=K+l
220 IF K<=N THEN GOSUB 2ae
230 RETURN

240 END

RUN

FACTORIAL 2

FACTORIAL 4

FACTORI-AL 5

120

STOP.
READY.

Functions
BASIC performs several mathematical calculations for the programmer, eliminating the need for tables of trig functions, square
roots, and logarithms. These functions have a three letter call
name, followed by an argument, x, which can be a number, variable, expression, or another. function. Table 1 lists the functions available in 8K BASIC. Most are self-explanatory; those
that are not and are provided in greater detail are marked with
asterisks.
Table 1

8K BASIC Functions

Function

Meaning

SIN(x)

Sine of x (x is expressed in radians)

COS(x)

Cosine of x (x is expressed in radians)
34

Table 1

8K BASIC Functions (Cont.)

Function

Meaning

TAN(x)

Tangent of x (x is expressed in radians)

ATN(x)

Arctangent of x (result is expressed in
radians)

EXP(x)

eX (e=2.718282)

LOG(x)

N aturallog of x (logex)

*SGN(x)

Sign of x-assign a value of + 1 if x is positive, 0 if x is zero, or-l if x is negative

*INT(x)

Integer value of x

ABS(x)

Absolute value of x (Ixl)

SQR(x)

Square root of x (VX)

*RND(x)

Random number

*TAB(x)

Print next character at space x

*GET(x)

Get a character from input device

*PUT(x)

Put a character on output device

*FNA(x)

User-defined function

*UUF(x)

User-coded function (machine language
code)

SIGN FUNCTION-SGN (X)
The sign function returns the value + 1 if x is a positive value,
o if x is zero, and-l if x is negative. For example, SGN(3.42)=1,
SGN( -42) =-1, and SGN(23-23) =0. The following example
in which X is assigned the sign of y illustrates the use of this
function:

INTEGER FUNCTION-INT(X)
The integer function returns the value of the nearest integer not
greater than x. For example, INT (34.67) =34. By specifying

INT(x+.5) the INT function can be used to round numbers to
the nearest integer; thus, INT(34.67+.5)==35. INT can also be
used to round numbers to any given decimal place by specifying:
INT (x* 1OtD+ .5)/1 OtD

where D is the number of decimal places desired. The following
program illustrates this function; execution has been stopped by
typing a CTRL/C:

10
20
30
40
50
60
70
80
90

REM - INT FUNCTION EXAMPLE
PRINT "NUMBER TO BE ROUNDED";
INPUT A
PRINT "NO. OF DECIMAL PLACES',';
INPUT D
LET B=INTCA*10tD+.5)/10tD
PRINT "A ROUNDED = "B
GO TO 20
END

RUN
NUMBER TO BE ROUNDED?55.65342
NO. OF DECIMAL PLACES?2
A ROUNDED = 55.65
NUMBER TO BE ROUNDED?78.375
NO. OF DECIMAL PLACES?-2
A ROUNDED = 100
NUMBER TO BE ROUNDED?67.89
NO. OF DECIMAL PLACES?-1
A ROUNDED
70
NUMBER TO BE ROUNDED?
STOP.
READY.

If the argument is a negative number, the value returned is the
largest negative integer (rounded to the higher value) contained in
the number. For example, INT(-23)==-23 but INT( -14.39)=-15.
RANDOM NUMBER FUNCTION-RND(X)
The random number function produces a random number between 0 and 1. The numbers are not reproducible, a fact the
programmer should keep in mind when debugging or checking his

program. The argument x in the RND (x) function call can be any
number, as that value is ignored. The following program illustrates
the use of this function to generate a table of random numbers:
10
25
30
40
50
60

REM - RANDOM NUMBER EXAMPLE
PRINT "RANDOM NUMBERS"
FOR 1=1 TO 30
PRINT RND(0),
NEXT I
END

RUN
RANDOM NUMBERS
.9547609
.05280478
.9848808
.5828625
.04672124
.2585353
READY.

.2890875
.3859534
.2466345
.7026891
.9868434
.5187701

.1416765
.8404774
.61588
.9703719
.5005693
.7858024

.2482717
.5692836
.4755698
.4980298
.1218251
.04588368

.2145417
.8514056
.3104984
.2548316
.2258269
.2030807

It is possible to generate random numbers over any range by
using the following formula:
(B-A)*RND(O)+A
This produces a random number (n) in the range A<n<B.
In order to obtain random integer digits in the range 0< == n<9,
line 40 in the previous example is changed to read:
40 PRINT INT(9*RND(0)),

When the program is run again, the results will look as follows:
RANDOM NUMBERS
8
8
0
3
3
8
2
2
6
7
0
2
READY.

(21

4
6

1
0

7
8

6
6

Notice that the range has changed to 0< n<9. This is because
the INTfunction returns the value of the nearest integer not greater
than n.
TAB FUNCTION
The TAB function allows the user to posItIon the printing of
characters anywhere on the Teletype (or line printer) line. Print

positions can be thought of as being numbered from 1 to 72
across the Teletype from left to right. (For printing devices with
long lines, the number of positions may be as large as 255, but it
is unlikely that more than 160 spaces will be required for most
printers.) The form of this function is:
TAB (n)
where the argument n represents the position (from 1 to the total
number of spaces available) in which the next character will be
typed.
Each time the TAB function is used, positions are counted from
the beginning of the line, not from the current position of the
printing head. For example, T AB(3) causes the character to be
printed at position 3; the following statement:

10 PRINT "X =";TAB(3);"/";3.14159

will print the slash on top of the equal sign, as shown below:

X ~ 3.14159

READY.

The following is an example of the sort of graph that can be
drawn with BASIC using the TAB function:

30
40
50
60

FOR X=0 TO 15 STEP .5
PRINT TABC30+15*SINCX)*EXPC-.l*X));"*"
NEXT X
END

RUN
*
*
*
*
*'

*
*
*
*
*
*
*
*
*
*
*

*
*
*
*
*
*
*
*
*
*
*
*
*
READY.

PUT AND GET FUNCTIONS
8K BASIC provides two additional functions, PUT and GET,
to increase input/output flexibility. Using these statements, the
programmer can "PUT" an ASCII character on the current output
device, or "GET" a character from the current input device. GET
is of the form:
GET (x)
39

where the argument x is a dummy variable which may be any
value. GET (x) will be assigned the decimal value of the ASCII
code of the next character input on the current input device.
For example, jf the following statement appears in a program:
Ie;, LET L=GETCX)

and the next character input is an M, the variable L will be assigned the value 77(10).
PUT is of the form:
PUT (x)
where the argument x represents the decimal value of the ASCII
code of the character to be output. For example, the statement:

15 L=PUTCGETCV))

will wait for a character to be read from the current input device
and then print it on the current output device. A statement such as:

30 PRINT PUTCQ)

will print the character typed as well as the decimal value of the
ASCII code for that character. To get 10 characters from a paper
tape and print them on the line printer, a suitable program is:
100
110
120
130
140
150

LPT
PTR
FOR A=l TO 10
LET B=PUTCGET(0))
NEXT A
END

The GET(O) will contain the most recently obtained character
which is then "PUT" to the line printer. The user should be careful
to position the tape on the first character to be input. Otherwise
40

blank tape may be entered, resulting in spaces being printed as
output.
The PUT statement can also be used to format output. For example, to print a trig table on the line printer with a heading and
50 data lines per page, the line feed character (12(10)) can be
"PUT" to the printer as follows:

100 LPT
110 GOSUB 1000
120 GOSUB 500
125 REM - SET UP TRIG TABLE
130 FOR J=0 TO 360 STEP .5
140 LET L=L+l
150 LET B=J/180*3.1~
160 PRINT J~SIN(B)~COS(B)~TAN(B)~ATN(B)
165 REM - PRINT 50 ENTRIES IN TABLE
170 IF L=50 THEN GOSUB 500
180 NEXT J
1 90 G0 SUB 1 000
200 GOSUB 1000
210 STOP
500 REM PRINT HEADER
50 5 G0 S UB 1000
510 PRINT
520 PRINT
530 PRINT "ANGLE"~"SINE"~"COSINE"~"TANGENT"~"ARCTANGENT"
540 PRINT
550 RETURN
1000 REM PRINT FORM FEEDS TO ADVANCE PAPER
1005 X=PUT(12)
1010 L=0
1020 RETURN
1030 END

The beginning of the line printer output from this program follows.
The first page of the table continues through an angle of 24.5 degrees: then the header and the next 50 entries are printed on the
next page, and so on until the values have been output for all angles through 360 degrees (in steps of .5).

ANGLE

SINE.

TANGt::~T

COSI""~

A~CTANGEIIJT

fl]

,5
1
1.5
2
2.5
3
3.5

8.722112E-rn
.0174435&
.026163&1:1
."'3488181
.134359729

,9Q99bc?
.9Q98479
.999&'571
.9993915
.9990492
.998&309
.99813&7
.99756&5
.996921l:5
.9961986
.995'1009
.9945274
.9935784
.9925537
.9914535

8.722444E-03
.01744&21
.02611264
.0349121305
.043&3878
.0523811&
.[£16113154
.06989125
.1217866164
• ~8 744408
.09623993
.1050506
.1138174
.1221211
.131585

8.722C1101E-03
.01744268
.02&1607
.03481,,74
.0435835
.05228564
.061397986
.0&966486
.07833935
.0871£HIJ20"
.095651&&
.10428&9
.1129"'67
.121512195
.1300944

,9136318
.9100512

.4449743
.4554645

"54.5
5.5
b

b.S
7
7,5

24
24.5

.0523094~

.06101763
.0b912111
.0784194
.1381111"7
.09579731
.1044751
.11314&1
.1218079
.1304604

The GET statement cannot be used to get binary characters.
FNA FUNCTION
In some programs it may be necessary to execute the same
mathematical formula in several different places. 8K BASIC allows the programmer to define his own function in the BASIC
language and then call this function in the same manner as the
square root or a trig function is called. Only one such userdefined function may be included per program. The function is
defined once at the beginning of the program before its first use,
and consists of a DEF statement in combination with a threeletter function name, the first two letters of which must be FN.
The format of the defining statement is as follows:
(line number) DEF FNA(x)=formula(x)
A may be any letter. The argument (x) has no significance; it is
strictly a dummy variable, but must be the same on each side of
the equal sign. The function itse,lf can be defined in terms of numbers, several variables, other functions, or mathematical expressions. For example:
10 DEF FNA(X)=Xt2+3*X+4

or
20 DEF FNC(X)=SQR(X+4)+1

The function:
10 DEF FNACS)=Sf2

will cause the later statement:
20 LET R=FNA(4)+1

to be evaluated as R== 17.
The user-defined function can be a function of only one variable.

USER-DEFINED FUNCTION - UUF
A special user-coded function is available for the programmer
who wishes to define an additional 8K BASIC function permanently or one which cannot be defined with one BASIC expression, as an FI'~A function must be. The UUF function routine is
coded in PDP-8 assembly language, assembled with one of the
available assemblers, and loaded as an overlay to 8K BASIC.
While 8K BASIC is running, the special function can be used in
a fashion analogous to the regular 8K BASIC functions. The usercoded function. if present, is referenced in the BASTC program as:
UUF(n)
where n can be any BASIC expression.
The programmer who defines the UUF function should be familiar
with the information on assembly language programming which
is in Introduction to Progranlnling 1972 chapters 1-5, and the
material on the Floating Point Package, chapter 8. He should also
be familiar with the information on the assembler he intends to
use by reading the appropriate manual.

Coding Formats
8K BASIC uses a floating point package which has been modified to allow 27-bit, sign-magnitude mantissa floating point. In
sign-magnitude convention the sign bit, rather than the mantissa,
expresses the sign of the entire number. This format is described
more fully below. All coding must be compatible with this format.
The floating point instructions are discussed later in this manual.
43

Upon entrance to the UUF subroutine the value of the argument is in the F AC (floating accumulator). The value which is
calculated for the function nlust be in the F AC in normalized
form on exit.
When floating point statements are to be included in the program, the start of a series of floating point instructions must be
indicated by the instruction:
FENTER
immediately before the first floating point instructions. Each series
of floating point instructions is terminated by the instruction:
FEXIT
immediately after the last floating point statement. There can be
as many sections of floating point code as necessary in the program, but each must be delimited in this manner.
Floating-Point Format
The floating-point format used by 8K BASIC allocates three
storage words to each number as follows:
WORD 1

WORD 2

WORD 3

IIII IIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIII

. . - - - - - - - . J ) ' ' - - - - -_ _ _ _---........".- _ _ _ _ _ _ _ _----J

EXPONENT

MANTISSA

SIGN BIT

The F AC occupies five locations on page 0:
Location Name

Location Number

Contents

ACS
ACE
AC1
AC2
AC3

0024
0025
0020
0017
0016

Sign
Exponent (200 8 biased)
High-order word
Mid-order word
Low-order word

The constant 200 8 is added to the exponent to make its range

o to 377.
All of BASIC's mathematical operations are in floating point
format. Therefore, if any temporary storage locations are to be
used, they will require three words, for example:

Addressing
The floating point package uses only relative addressing. Therefore all statements that require an address specification must include one of the operators FWD or BKWD plus a reference to
the current location. Such ,et.~~r~AS~:)~~<t.&~nerally of the form:
~.- ... -,"--C-:":.

r.:-

instruction+FWD+LtEMP~ .. ·
~di'(
'tti',Jr. -A.t.; .,,'\~ ~~
".;:t,

~-.--

instruction+BKWD+.-LTEMP'
.where L TEMP is the first of the three locations containing the
number to be used. The operator FWD is used when the address
of the location to be referenced is numerically greater than the address of the instruction; BKWD is used when the address of the
location to be referenced is numerically less than the address of the
instruction. The floating point interpreter uses the number of
locations between the instruction and the data to locate the data.
The location referenced must be within 200 8 locations of the
instruction.
The following two examples cause the contents of L TEMP to
be added to the contents of the F AC, and the result left in the
FAC:
00200 4210

F'AO+ F'W O+L TEMP-.

00210 0000 LTEMP
00211 0000
00212 0000

o
o
eJ

or
00200 0000 LTE;'<1P
00201 0000
00202 0000

o
o
o

00210 4610

FAO+ 8:·{'.oJ 0+ • -L TE~P

Floating-Point Instruction Set
The legal instructions in the modified Floating-Point Package
used by 8K BASIC are explained in Table 2 :
45

Table 2

Floating-Point Instructions·

Instruction

Value

Meaning

FST

2000

Store the contents of the floating accumulator (FAC). The contents of the
FAC are not changed.

FLD

3000

Load FAC with contents of relative
address.

FAD

4000

Add contents of relative address to
FAC.

FSB

5000

Subtract contents of relative address
from FAC.

FMP

6000

Multiply the contents of the FAC by
the contents of the relative address.

FDV

7000

Divide F AC by contents of relative
address.

FJMP

1000

Floating-point jump to relati ve address.

FENTER

4435

Start floating-point code.

FEXIT

0000

Exit floating-point code. Return to
PDP-8 code.

FWD

0200

Access a relative location in the forward direction.

BKWD

0600

Access a relative location in the backward direction.

FSNE

0040

Skip if FAC

FSEQ

0050

Skip if FAC = 0

FSGE

0100

Skip if FAC ~ 0

FSLT

0110

Skip if FAC < 0

FSGT

0140

Skip if FAC > 0

FSLE

0150

Skip if FAC ~ 0
46

The following list contains floating-point instructions for indirect relative addressing. The indirect addressing is similar to the
I construction used in regular PDP-8 assembly language coding.
Floating-Point Instructions (Indirect Relative Addressing)
Instruction

Value

Operation

FSTI
FLDI
FADI
FSBI
FMPI
FDVI
FJMPI

2400
3400
4400
5400
6400
7400
1400

Store
Load
Add
Subtract
Multiply
Divide
Jump

Writing the Program
UUF must be made a defined function for 8K BASIC. This is
done by inserting the starting address of the UUF subroutine in
BASIC's table of subroutine addresses. The subroutine address
must be placed in location 1156 of field O. If UUF is the first
location of the subroutine, the following code is sufficient:
*1156
UUF
The UUF subroutine may be placed in the area of core normally occupied by the RIM and BIN loaders, location 7600-7777
of field O. To do this, the loaders are placed in field 1. The loading
instructions for UUF are contained in the section called Loading
and Operating Procedures.
If mass storage devices are in use, they may destroy the data
break locations on the last page of field O. If TC08 DECtape
is used, locations 7752 and 7753 must be reserved. If an RF08
or DF32 disk is used, locations 7750 and 7751 must be reserved.
There are three subroutines in 8K BASIC which are available
to maintain a floating-point format acceptable to the modified
floating-point package in 8K BASIC. These subroutines are described below. The listing of 8K BASIC is available from the
Software Distribution Center for the programmer who wishes to
call other subroutines in the compiler.

BEGFIX

If a value is to be returned to the F AC as a result
of the UUF function, that value must be in normalized floating point format in the FAC on exit
from the subroutine. If floating point arithmetic is
used throughout the user function, then the value
in the F AC is in normalized floating point format
and need not be converted. If fixed point arithmetic
(single word) is used anywhere in the function,
then the subroutine BEGFIX must be called to
initialize the F AC before the fixed point number
is placed in the F AC and subsequently converted
to floating point (see ANORM below). After
BEGFIX is called, the 12-bit number is stored by
a simple DCA AC3 instruction and then ANORM
is called. BEGFIX is located at 3762 and is called
with a JMS instruction; on return from BEGFIX
the AC is clear.

ANORM

If a fixed point value is placed in the F AC,
ANORM may be called to normalize the FAC.
After the fixed point value has been placed in AC3,
ANORM may be called to supply the acceptable
values for ACE, ACS, ACl, and AC2. ANORM is
located at 4600; on return, the AC is clear.

FIX

When the value in the F AC must be made into an
integer, FIX may be called to perfom that job. The
12-bit value of the F AC is left in AC3 and that
value plus 1 is left in the AC. FIX is located,}'t
4744.

Examples
The following examples illustrate the method of writing and
calling a UUF routine.
Example 1:
This UUF routine is an example of a fixed point calculation.
The value of UUF(X) is 3X+2.

'AGE t
IUUF(x)a3X.2
tENTER WITH X IN FAC
IEX!T WITH UUF(X) IN FAC
IUSE FIXED POINT ARITHMETIC - !
1211211&
4744
37&2

121115&

tl60~

000121

FIELD 0

115&

*1156

1211210~

4215

0'(,121'

~&2a

1217&10
07611
1217&12
07613
1217&ia

7326

07&15
07&1&
1217&11
07&20
1217&21

1210121121
1222

121

JMS I IFIX
CLA
DCA ANSWER
JMS LOOP
JMS LOOP

7200
3222
4215

07&1216

07&2;!

*760121
UUF,

t1&23

(37612l5

1217&23
1217624
1217f125

UUF

7b0~

1&1210
07&121121
017&0\
1217&1212
07&03
07&0U

AC3-1&
FIX-4744
BEGFIX=37&2
ANORM a ab012l

IMAKE

12-BIT INTEGER.

/5.e-tAC~a

15:+ ANs:/i

I~ULTrpL.V

)( BY 3

JMS ~OOP
JMS I IBEG
CLA r:Ll.. CML RTL ISET AC-2
I~ETCH 3)(
TAO ANSWER
IRETURN 3)(.2 TO FAC
DCA AC3
INORMALIZE
JMS I INORM
I--RETURN··
JMP I UUF

1222
3016
4625
5&1210

LOOP,

121

TAD ANSrlER

IAOO At] TO ACCUMUL.ATEO SUM

TAO AC3
DCA ANSwER
J~4P I L.OOP

112116
3222
5&15
12101210
4744
3762

ANSWER, 0
IFJX,
FIX

IBEG,

BEr.FIX

4Et00

I NORM,

ANORM

The following BASIC program calls UUF(X) to print X and
3X+2 for a number of values of X:
READY.

100 FOR X=-3 TO 3 STEP .5
110 PRI~T ~~
120 .'l EXT X
130 END

UUF(~)

RU:\1

-3
-2. 5
-2

11
11
g

- 1. 5

8
5
5
2
2
5
5

- 1

-.5
"0

.5
1

1. 5
2
2. 5

3
8

READY.

Example 2:
This UUF routine is an example of a floating point calculation.
Like example 1, this routine returns a value of UUF(X)=3X+2.
PAGE 1
IUUF 0' a3lt+2
IENTER WITH X IN FAC
IEltIT WIT~ UUF(X) IN FAC
IUSE ~~ING ~~"~NT ARITHMETIC
4435

FENTElh4l£35

2000
0200
0000

FST;:a2000

&000
l£000
001~

31&2
1J&00

ANO~M"Q&00

0000

FIELD 0

1156

*1156

01156

1&00

07&00

7&00
0000
l£435

0"~l2Il

1211&0?
1217603
01&0a
1211605
07&0b

FWO-200
FEXIT=0000
FMPn&000
FAOa4000
AC3 8 16
BEGFIX:;3762

221&

0000
132'S

l£ii4
l£435

CH~07

6il1

07610

2210

07& 11

1217&12

0210121
73i&

1217&13

4224

UUF

FENTER
FST+FWO+X-. ISTORE X FROM FAC INTO Loe, x
FEXIT
.~;:
ClA Cll CMl lAC RAl
ISET AC-3
J~S FLOAT IGET A FLOATING POINT 3 IN THE FAC
FENTER
FMP+FWO+X-.
IMULTIPLY X BY J
FST+FWO+X-.
ISAVE IT FOR lATER
FEXIT
CLA CLL C~L RTl IGET A 2 IN THE FAC
JMS FLOAT

01&14
01&15
07&1&
07fl17

4435
4203
0e'00
5f>00

t'l1b20
07&i?1

)(

010'0

011,22

0000
0000
0000

07&23

121000

TEMP,

- 07&24

0et00
3223
4633
1223
301&
4&34
5&24

FLOAT,

37&2
4600

IBEG,
INOIlM,

01~25

1211&2&
01&21
07&30
01&31
01632
07b33

211611.1

FENTEQ
FAD.FWO.)(-,
FE)(IT
JMP I UUF

IAOD 2 TO 3)(
ILEAVE RESULT IN FAC
I--RETURN-·

OCA TEMP
JMS I IBEG
TAD TEMP
DCA ACl
JMS I INORM
JMP I FLOAT

ISTORE CONSTANT TEMPORARILY
IPREPARE FAC TO RECEIVE VALUE
IPUT CONSTANT IN FAt
INORMALIZE IT
I·-RETURN .. •

BEGFI)(
ANORM

IUUF on -])(.2

PALl-V?

5/25/72

PAGE t-l

s
The following BASIC program"calls UUF(X) to print X and
3X+2 for a number of values of X. The results differ from those
in example 1 because of the capability of floating point arithmetic
to handle fractions.
READY.
100 FOR X=-3 TO 3 STEP • 5
110 PRINT
UUFC X)
120 \JEXT X
130 END

RU\I

-3
-2.5
-2
- 1. 5
- 1
-.5
0
•5
1

-7
- 5. 5
-4
- 2.5
- 1

t. 5

•5
2
3.5
5
6.5

2
2.5

9.5

READY.

Example 3:
This UUF routine computes the square of the argument in floating point format.
IUUF(X)-X·2

IENTER wITH X IN 'AC
IExIT WITH UUFeW) IN FAC
IUSE FLOATING POINT ARITHMETIC
4435
20210
21200

FENTER-4435
FS1-2000
F"'0-200

602121
21000

FMP-&2100
FExIT-0000

21000

FIELD 0

115&

*115&

UUF

0115&

7700

01100
011211
011212
01103

21000
"''''35

"FENTER
FST.F",O.X-,

6203

01104
01105

21000
5100

FMP.FWO.X.,
FEXIT

ISTORE ARGUMENT IN X
IMULTIPlV FAC 8V ~OC.
IRESULT IS IN FAC

JMP I UUF

ltot-RETURN··

01106

0000
0000
0000

7100

01701
011UI

*1100
UlJF,

22214

x (X-X)

0'0,0

The following BASIC program uses the above UUF to produce
a table of squares and square roots:
READY.
100 FOR A=1 TO 10 STEP 1
110 PRI NT AI UUF( A) I SQR( A)
120\J EXT A
130 EN 0

RU:\J
1
2
3
4

5
6
1
8
9
10

4
9
16
25
36
49
64
81
100

1.414214
1.132051
2
2.236068
2.44949
2.645151
2.623427
3
3.162218

READY.

EDITING AND CONTROL COMMANDS
Errors made while typing at the console keyboard are easily corrected. BASIC provides special commands to facilitate the editing
procedure.
Erasing Characters and Lines
SHIFT /0, RUBOUTS, NO RUB OUTS
There are two methods available for erasing a character or
series of characters one at a time. Typing a SHIFT / O' causes the
deletion of the last character typed, and echoes as a back arrow
( ~) on the Teletype. One character is deleted each time the key
is typed.
The RUB OUT key may also be used for deletion of characters
one at a time providing the command:
RUBOUTS

has been typed on the keyboard before the editing is done. This
command enables the RUBOUT key to be used. If the user has
neglected to type this command, he may not use the RUBOUT key.
A later command of:
NO RUBOUTS

disables the key for use. (This is desirable when programs created
on other systems which use rubouts as null characters are to be
read into core. See the section entitled PTP AND LPT under
Listing and Punching a Program.) For example:

The user types a B instead of T and immediately notices the mistake. He may type SHIFT /0 (or RUBOUT key, if enabled) once
to delete the B, and as many times more as characters, including
spaces, are to be deleted. After the correction is made, he may
continue typing the line. The typed line enters the computer only
when the RETURN key is pressed. Before that time any number
of corrections can be made to the line.
53

When the RETURN key is typed, the line is input as:

Notice that spaces, as well as printing characters, may be erased.
The user may erase an entire line (provided the RETURN key
has not been typed) by typing the ALTMODE key (ESCAPE
key on some keyboards). BASIC echos back:
DELETED

at the end of the line to indicate that the line has been removed.
The user continues as though it were a new line. If the RETURN
key has already been typed, the user may still correct the line by
simply typing the line number and retyping the line correctly. He
may delete the line by typing the RETURN key immediately after
the line number, thus removing both the line number and line
from his program.
If the line number of a line not needing correction is accidentally
typed, the SHIFTjO or RUB OUT key may be used to delete the
number(s); the user may then type in the correct numbers. Assume the line:
10 IF A>5 GO TO 230

is correct. The programmer intends to insert a line 15, but instead types:
10 LET

He notices the mistake and makes the correction as follows:
10

LET~~~~~5

LET X=X-3

Line 10 remains unchanged, and line 15 is entered.
Following an attempt to run a program, error messages may be
54

output on the Teletype indicating illegal characters or formats, or
other user errors in the program. Most errors can be corrected by
typing the line number (s ) and the correction (.S ) and then rerunning the program. As many changes or corrections as desired
may be made before runs.

Listing and Punching a Program
LIST
An indirect program or data can be listed on the active output
device by typing the command:
LIST

followed by the RETURN key. The entire program (or data) will
be listed.
A part of a program may be listed by typing LIST followed by
a line number. This causes that line and all following lines in the
program to be listed. For example:
LIST 100

will list line 100 and all remaining lines in the program.
PTP AND LPT
The LIST command may be issued in conjunction with the LPT
or PTP commands as follows:
PTP
LIST

LPT
LIST

This will list the current program on the high-speed paper tape
punch or line printer respectively. Control is reset to the Teletype
after the listing is completed.
Occasionally, when 8K BASIC is reading in a program from the
low-speed reader, it may drop a character since the Teletype
buffer cannot accept input at a prolonged fast rate. To eliminate
this possibility, use LIST as follows when punching out paper
tapes:
55

PTP

LIST*

This inserts null characters after carriage returns and is recommended when punching any tapes that will later be read in from
the low-speed paper tape reader. (8K BASIC does not use rubouts as null characters.)
Reading a Program

PTR
The PTR command can be issued to read in a paper tape from
the high-speed reader. This mode is particularly useful for reading
in a user-coded "load and go" BASIC program. The tape should
be positioned in the reader before the command is issued; if not, or
if the reader runs out of tape, BASIC prints;
TTY

on the Teletype to indicate that there is no more input from the
high-speed reader, and that it is waiting for input from the Teletype.
The user may cause tapes to be read in from the low-speed
reader by simply placing the tape over the sprocket wheel and
setting the reader to START.
Running a Program

RUN
After a BASIC program has been typed and is in core, it is
ready to be run. This is accomplished by simply typing the command:
RUN

followed by the RETURN key. The program will begin execution.
If errors are encountered, appropriate error messages will be typed
on the keyboard; otherwise, the program will run to completion,
printing whatever output was requested. When the END statement is reached, BASIC stops execution and prints:
READY.

PTP AND LPT
Either the high-speed paper tape punch or LP08 line printer, if
available, can be used in conjunction with the RUN command.
After the command is issued, all output during program execution
is diverted from the Teletype to the specified. device. The command sequence is:
PTP

LPT

RUN

This procedure eliminates the need to insert the PTP (or LPT)
statement within the program. Output returns to the Teletype
after execution.

Stopping a Run
CTRLjC
To stop a program during execution or to return to BASIC at
any time, type a CTRL/C (accomplished by typing the CTRL
key and the C simultaneously). This causes the current operation
to be aborted immediately, and the message:
STOP.

READY.

to be printed indicating that an 8K BASIC command can now be
issued.
CTRL/O
The command CTRLjO (caused by typing the CTRL and 0
keys down simultaneously) is used to stop output temporarily. The
program will continue to execute but output will not be printed on
any output device unless an error occurs or unless BASIC is
waiting for a command or for data from an input statement. In the
latter case, the Teletype is the expected input device. This feature
is particularly useful for programs that print lengthy introductions
and then request a user-specified parameter. Typing CTRL/O
after the program is started will cause BASIC to bypass printing
the introduction and wait until the parameter is specified, thereby
saving the time required to print the message. A second CTRLj 0
will resume output.
57

NOTE
For most programs that do not wait for
input from the Teletype, processing of the
program after an initial CTRLjO will be
completed before a second CTRL/O can be
typed. Thus, it is very possible for no output
to be printed rather than the anticipated
partial output.
Erasing a Program in Core
SCR
The command:
SCRATCH

or
SCR

is provided to allow the programmer to clear his storage area,
deleting any commands, or a program which may have been
previously entered, and leaving a clean area in which to work. If
the storage area is not cleared before entering a new program,
lines from previous programs may be executed along with the
new program, causing errors or misinformation. The SCRATCH
command eliminates all old statements and numbers and should
be used before any tapes are read into core, or new programs
created.
LOADING AND OPERATING PROCEDURES
BASIC Compiler
The following procedure may be used to load in the 8K BASIC
binary tape.
1. Toggle the RIM Loader into field 0 and, using the appro-

priate reader, read the Binary Loader into field O. (Refer
to Appendix A for details.) 8K BASIC will not use locations 7600 to 7777, thereby preserving the Binary Loader if
it is present.
2. Place the 8K BASIC binary tape in the appropriate reader;
set switches 6-8 == 0, and 9-11 == 0; press EXTD ADDRess
LOAD.
3. Set the Switch Register == 7777 and press ADDRess LOAD.
58

4. If using high-speed reader, set the Switch Register =
3777 and press CLEAR and CONTinue; otherwise, simply press CLEAR and CONTinue.
S. After the tape has read in, set the S~tch Register = 1000.
6. Press ADDRess LOAD, and CLEAR and CONTinue.
BASIC responds by typing READY.
7. BASIC programs on paper tapes may be read in using the
PTR command explained earlier, or created on-line.
User- Defined Function
The following procedure may be used to load in a user-defined
function.
1. Load the Binary Loader into field 1.
2. Load BASIC into field O.
3. Load the user-function (binary paper tape overlay) into
field O~·~/i~.~, ~ r t'" .,{ ~ .,"/ .~.
4. Set Switch Register = 1000; press ADDRess LOAD and
START.
'~ "'.:"''" ,';. L
\

Note that the Binary Loader is destroyed. To reload BASIC,
steps 1 through 6 must be repeated.
8K BASIC ERROR MESSAGES
The computer checks all commands before executing them. If
for some reason it cannot execute the command, it indicates this
by typing one of the error messages. The number of the line in
which the error was found is also typed out. The form is:
ERROR MESSAGE AT LINE XXXX
Table 3 lists the errors 8K BASIC checks for and reports
before execution:
Table 3

8K BASIC Error Messages

Message

Meaning

ARGUMENT ERROR

A function has been given an illegal argument;
for example:
SQRC-l)

DATA ERROR

There are no more items in the data list.

FOR ERROR

FOR loops are nested too deeply.

FUNCTION ERROR

The user has attempted to call a function which
has not been defined.

GOSUB ERROR

Subroutines are nested too deeply.

LINE NO ERROR

A GOTO, GOSUB, or IF references a nonexistent line.

NEXT ERROR

FOR and NEXT statements are not properly
paired.

RETURN ERROR

RETURN statement issued when not under
control of a GOSUB.

SUBSCRIPT ERROR

A subscript has been used which is outside
the bounds defined in the DIM statement.

SYNTAX ERROR

The command does not correspond to the
language syntax. Common examples of syntax
errors are misspelled commands, unmatched
parentheses, and other typographical errors.
Reference to an undefined UUF will also produce this diagnostic.

TOO-BIG ERROR

The combination of program size and number
of variables exceeds the capacity of the computer. Reducing one or the other may help.
If the program has undergone extensive revision, punching it out, typing SCRATCH
and reloading should be tried.

The following programming errors are not reported by 8K
BASIC, but instead are used in the computation as specified. They
are included here for the programmer's reference.
1. Attempting to use a number in a computation which is too
large for BASIC to handle will produce a result which is meaningless.
2. Attempting to use a number in a computation which is too
small for BASIC to handle will result in the value zero being used
instead.
3. Attempting to divide by zero will produce a result which is
meaningless.

BASIC SYMBOL TABLE
Table 4 lists 8K BASIC's symbols and their values. This
information IS useful when writing user-coded (machine language) functions.
Table 4
A3CJEr
A3DGET
A30P
ASS
AC1
A:2
A:3
ACCEPT
A:E
ACN
AC:OUNT
ACS
A::JA1
AJA2
AJA3
AJACPT
AJ8
AJC
AJGCOR
AGCl
AJCUNT
AOCX
AJLJRES
AJLE
AJL"1
AJRB
Al)RS
AJSE
AJSK
AJST
AGET
ALl
ALG\JL.P
ALL3
ALlOC
AI.. Ti"IOD
AMATCH
A\jOR~

AP0T
A?0 T1
APUT2
ARl

1750

BARROW

e0~6

BCDE~G

~325

BCKWOS
BEGFIX
SIDLE
BKWD
BREAK
BSKIP
BUSY
CARRET
CCINTK
CCXRA
CDEVCO
CDINP
CHECKW
CHKFIT
CLAB
CLBA
CLC
CLCA
CLEAR
CL.EARV
CL.EN
CLKSTS
CL.OCKI
CL.OE
CLRCNT
CL.S
CL.SA
CL.SK
CL.T(MP
CltE
CNCLR
CNTLCF'
CNTLCR
Ct'-lTL2
CODELO

6425
2020
0017
~016

7473
0025
4417
e~22

0024
Ck'J25
e026
e'''27
e0f2l7
7477
7477
012164
6530
~01"

e012

e067
6536
6531
6533
6537
6535
6534
6532
0301
4654
4466
3146
1461
2663
6506
46021
2'263
0.023
0024
44~2

A~GERR

7363

ARRlOC
ATE"1P
ATEMP2
ArlINE
ATN
ATNSI::;
AT~~ L0 i'J
AT\I"JOT
AUTEHP

e!323
0324
6451
6200
6265
6220
6237

~003

~063

COLU~N

COMMON
COMPAR
CONST
COS
COWT
COWTFP
COL-HLP
COWTO
COWTW
CRINTX
CRL.r
CRLrPR
CTl
CT2

8K BASIC Symbol Table
CT3
CVTLOO
DATAER
DBAD
DBBAD
DBGOT
DBISRT

2666
1757
4502
3762
6713
f2l60~

6522
2730
6737

DB~IT

DBPUT
DDLAST
DECEXP
DECFRA
DEEPER
DEF'
DELAY
DELETE

27"'~

7465
7:542
~00~

7445
2346
640~

6133
6136
7477
6137
7432
2462
6134
012103
0175
6132

DE~OUT

DEVCOM
DEVCON
DICD
DIGIN
DIGIT
DIGLUP
DILC
DILE
OILX
DILY
DIM
DIMF'LA
OINP

036~

7477
6135
6131
0~11

DIRE

613J
0143
67021

OISAUT
DISB
DIS0
DIVL.P
DIVXTE
OIXY
DLAST
DOAO
DOADLP
DOITNO
DOTtER
DPF"L.AG
DCINTX
DSCREW
DVL,OOP
EDIT
END
ENOLIN
ENONUM
ENDPDl
EOF'AD

667~

0133
0004
0126
340~

2136
1367
5616
7326
7343
7331
734~

7344
3076
6531
374;:'
0016
f2l2J15

~IiH4
50~4

1667
1513
'5~2

1420
1547
7526
1556
7512
~043

33~6

0526
1516
1463
6501
0142
7175
71'6
6051
3224
32~4

6557
6050
6056
621'33
6054
6472
0~:54

7511
62157
012115
0136
621'2
~705

33&4
6055
1511
~362
~366

1247
13'1
33&5
31'0
03'5
5245
2405
2'~7

7643
3331
111.'J4
45~6

EPTR
ERROR
EVAL
EVALGO
EX£CUT
ExIT
EXP
ExPGOO
EXPLON
EXPOK
F'AD
F'ADEXT
tAD I
F'ATNAX
F'ATNC
F'ATNC1
F'ATNC2
F"ATNC3
F"ATNC4
F'ATNC5
rATNC6
F'ATNC7
F'ATNCS
rATNC9
F'ATNCH
rATNCJ
F'ATNSX
F'ATNT
F"ATNTT
F'CNTLC
F"CNTLO
F'DIGIT
F"DV
rDVI
F'ENTER
F'EXIT
F'EXPC1
F'EXPC2
F'EXPC3
F"E)(PC4
F'EXPC5
F'E)CPC6
F'E)(PF'
F'EXPI
F'E)CPU
F'INDIT
F'INDLU
F'IX
F'IXEXI
F'IXITU
rl)CLIN
F'IXLUP

~056

4142
10214
10217
0213
24212
60211lJ
5242
5'64
5265
40210
1314
4400
6273
6337
63214
63217
6312
6315
63221
6323
6326
6331
6334
6342
6345
62'12
6276
6301
6665
6103
3360
700(21
7400
4435
21000
6012
62115
6Hl(21
61213
61216
611i
6067
6061
6064
rlJ5'7
1lJ5&5
4144
41'3
5200
2113
4"0

FIXU~

F"JMP
FJMPI
FJUMP
FLO
F"lO!
FLOGel
FLOGC2
F"LOGC3
FLOGC4
FMP
F'~PI

F'1T1
FMT2
n1T3
FMTENF
FN
F~E~R

FNEXIT
FOR
FORCT
F'ORDON
FORERR
F'~RLIM

F"ORLIS
F'ORSTE
FORVAR
F'OUND
F'OURLF
FPADo
FPADoR
F'POIV
FPDOIT
FPFlAG
FPGOTO
FPJMP
FPJUMP
FPLAC
FPLOOP
FPMUL
FPNOAD
FPOPER
F'PPGZ!
F"PSKIP
F'PSTO
FPSUB
FPT
FPTEMP
F'PTR
F'PlDIV
F'RNDX
FRSTNE

5146
10210
14eJ0
113"
3212121
34121"
6175
6156
6161
6164
6"0121
64021
5125
5"53
513"
5123
5453
0352
12fZ1"
0413
"12163
"663
fZl501
0721
7705
0724
0452
~575

3557
4456
4304
4667
4231
0156
4273
4317
4274
4351
4202
453k'l
42721
4305
4227
4314
4322
4453
42021
4576
0057
4736
5404
2155

FSB
FSBI
FSEQ
FSGE
FSGT
FSHIFT
FSINll21
FSINC1
F'SINC3
F'SINC4
F'SINC5
FSINC6
FSINC7
FSINM4
FSINOK
FSINr
FSINt~

F'SlE
F'SlT
FSNE
FSQRX
FST
FSTI
FTANTl
F'TANT2
FUNTAB
FUPRC1
FWD
FXXPFX
GALT
GDIM2
GET
GETADD
GETARY
GET8LK
GETCH
GETJ
GETLIN
GETLRE
GETOPR
GETVAR
·GETWD
GLOOP
GOBOTH
GOlIST
GOSUS
GOTEMP
GOTO
GOTOPR
GOTSS
GOTSTE
GOUT

5~~~

GP'iP

540~

G~B
G~OElA

~1215~

GSBEND
GSBPTR
GSS1
.GSS2
GTBKLP
GTEMP

0100
fZl14~

7443
5641
5713
5716
5721
5124
5727
5732
5735
5657
57a5
5110
fZl150
al1fZ1
12104121
54fZ17
2fZ1a21
24fZ10
5677
571212
1131
5162
fZl2fZ1fZ1
6B23
7247
1564
IlJB"l

GW~ERE

HF'OUND
HIGHWD
HL.OOP
HPTR
H~CHAR
H~LOP

HRMES
IAMLES
IOL.EAC
ICL.ECo
IOLECI
IOL.ElK
IOLEPC
IF'
IGNORE
I I XR
P1MED
IN
iNCHAR
INCEV
INOEXl
INOEX2
INLCTM
INL.OOP
INI.UPF
INODUN
INOPPP
INOTTT
INPLUP
INPPTR
INPUT
INSERT
INSRT5
INT
INTAC
INTCDF
INTCIF
INTECD
INTEMP
INTER
INTEXT
INTL

1421~

7462
1674
72fZ11
1770
26"3
26Z0
112115
0311
0177
2711
1lJ532

1725
05"5
0Z53
fZl517
12"2
1174
"634
7251

2112160
1224
1222
1155
0165
1562
1'63
11i2J
12!!J.4
12'121
1321
4333
2722
IUI61
12'6
13m2
1323
21'6
6732
6725
6126
6731
6733
121315
2115
7414
24'4
34!1
'2~5

18127

12112113

ml2l!.

412165
fZl5'2
rll432
671QJ
6641
6645
4034
412163
4mQl7
212132
2121!2J
6434
6134
61'21
6711
6162
67!6
66~QJ

6744
6735

INTOU
INWDTM
IPNOPE
IPOINT
ISOEF'2
ISOIG
ISOIM
%S[T
IS1T
ISITOF'
ISITF'U
ISITlI
ISLIT
ISSOME
ISUMIN
ITSDEF'
ITSDP
ITSE
ITSOP
ITSF
JBPENT
JOIGIT
JISOIG
JMATCH
JPUTCH
JTXXIT
JuSTa
JUSTrllF'
JUSTI!P
JUST1
JUST2
KEYWD
L4LUP
LBEGIN
LOF'
LET
I.EToO
LETTER
LF'XLUP
L~.LF'

LIMIT
L.INBUF'
LINENO
LINF'IX
LIST
LIST2
LIST3
LIST4
LIST'
LISTAL
LISTLU
L.ISTSO

6765
42164
42124
12134
3512
6532
1473
14137
4566
1215,a
l11a
41134
4133
1644
112113
3514
3256
3263
122121
33mB
37m7
3124
3367
2;66
121777
3123
31,a
316a
3163
3145
.3147
21231
3664
'563
6662
"312
1212185
3446
2333
3B;"
12121213
'512
1210'2
2331
36~QJ

36421
36'5
366136;6
3616
3621
3617

L.ITRAL
L.LLJMP
L.L.LJMS
L.L.LUUU
L.LS
L.NOEND
LOADED
L.OCCTR
LOCTEM
L.OCTMP
L.OG
L.OGACE
L.OGF"WD
L.OGOKW
L.OWL.OC
L.PTOUT
L.SF"
L.STL.OC
L.UP
L.UPF"
MACHIN
MAYi!ER
MENDL.I
MENOF'D
MEVAL.
MEVAL.G
MGOL.IS
MGSBEN
MINUS
ML.BEGI
ML.ENO
ML.INBU
MNSONE
MOREOI
MOREIN
MORERO
MOVE
MOVLUP
MPy
MPYLUP
MTXXIT
MULCL.R
MULEXP
MUL.XTE
MU5TBE
NOELAY
NEwCHA
NEWLIN
NExT
NEXT[R
NEXTVA
NINTEC

3131
7457
7446
7141lJ
6666
363121
4127
21045
12J671
1673
6114
617"
6167
6172
2171
7163
6661
216121
34215
21426
1lJ01210
4612
12J041
2363
7415
7431
121720
fl)525
1316
0173
121174
004f1)
121736
64711
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1621
2f1)12
21172
5321
4552
32l2Jl
4571
3346
3363
4570
7421
2615
2611
12J6211lJ
12J673
1631
1457

NOBUMP
NOCOMM
NOINT
NON8LN
NONlER
NOPARE
NOPCR
NORLFT
NORMED
NORMIT
NORUBO
NOSSl
NOSS2
NOT
NOTBAO
NOT8IG
NOTCR
NOTF"RS
NOTHER
NOTKWO
NOTNOW
NOTSGN
NOTTXT
NOTVAR
NOTX11lJ
NPSPER
NSYMTA
NULCMO
NULJOB
NULL.OF'
NUM8UF"
o lQJfI) 121
011
0110
012
0122
013
0132
0137
014
0140A
01418
0143
017
01742
0175
0177
01774
02
02fJfI)
02140.
02162

0QJ11lJ
0212
0QJIlI?
0215
023
1366
0233
3"2
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024"
02'3
51'1lJ
51tl
02'5
51~6
02'6A
02'68
65"
0111
026"
33'21
02'
03QJ5
51'2
032
3121
. 27.7
036
03'378 27'3
03'54
1162
03'155
12'3
03'7
01lJ'1
04
0160
041
21'0
o 4f1)fI) 1
7525
04114
1163
042
31~6
0421UJ
311115
04213
1164
054f1)fI)
5347
06211A 66!5
062118 71lJ1lI5
06212
67'5
01
01'2
070
67'4
07111lJ
12'2
011l1QJfI)A 2'611
O'lIlf1)B 34'"
0'11110C ;"!l6
071177
12"
01'2f1)
51!13
0'1'45
4"7
64!16
0"71
07'77
4"7
01'778
0'61f1)
43 .. 5
01611
'2611
0'1'1lJ3
21'4
01611
5:5"
07612
'262
01641A 187.,
07'411B 2763
076411C '263
01673
33{6
017
211'11
01716A 6'.4

4633
12J335
12J134
311121
51lJ16
lQJ35
2216
6423
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5212J7
5574
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3427
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21313
2f1)IlJQJ
3311J1
2236
11"5
5236
7555
IlJfI)I2J6
7454
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743121
5335
355121
05"4
2361
0165
2771
1'67
7265
7261
236"
12J775
2772
7266
5147
3315
7267
211121
3376
1162
21155
3373
5344

", ..

0111lJ6C
07115
0"25A
01'2'8
01'37
0114QJ
01141
01'43
07145
07146
07153
0;162
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07'64B
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01'71lJ
07171
07172
07'73
07'174
01175
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07'177
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OBL.OW

oeop

ace

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OCOUNT

ootv

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OF"LOW
OJUMP
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ONE
ONEOIM
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00'16111
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opt

OP2
OP3
OPOONE

OPE

OPERAN

34;3
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IIIi3
11112
11121
12i3
11131
111'3

OPNUL
OPOINT
OPOTAB
OPRST
OPS
OPUTC
OTEMP
OTHER
OTSTl
OUTD2
OUTDEL
OUTDEV
OUTIT
OUTNUM
OV
PAeN
PALl
PANORM
PAR'l
PAAGER
PASSCR
PASSUM
PBEGF'I
PBIDL.E
PBOMB
PBUSY
PCCUNT
PCHKF'I
PCOMMO
PCOWT
PDEVCO
POL
POLIST
PEOIT
PERMSY
PERROR
PEVAL.
PEVALG
PEXECU
PEXP
PF"INOI
PF'IX
PF"NERR
PFPLOO
PGET AD.
PGETeL
PGETCH
PGETLI
PGETL,R
PGETOP
PGETVA
PGOLIS

1067
7~65

7073
7155
0026
7141
1271
3010
1112
1211'30
7146
121131
7QJ43
5QJI0
I2IQJ12
4742
"'1'0
121146
121147
I2IQJ47
0472
744'"
1716
7161
0367
7157
0744
0163
3357
0141
7442
I2IQJ36
7644
0120
1022
0QJ77
011211
2240
0103
5776
121672
01"6
5546
4575
0102
0115
0QJ32
0124
3QJ22
0111
0113
0164.

PGOTOP
PHRCHA
PIGNOR
PINCHA
PINT
PISITL
PJSET
PLBEGI
PLETDO
PLETTE
PLIMIT
PL.INBU
PLINFI
PL.IST
PL.ITRA
PL.OG
PLoOT
PL.OTB
PLUS
PMEVAL.
PMPY
PNBF"6
PNOCR
PNONBL.
PNOTNO
PNUMBU
POADD
POF"LAG
POP
POP3
POPERA
POTHER
POUTIT
POUTNU
PPACl
PPAC2
PPAC3
PPACE
PPACS
PPASSC
PPOLIS
PPERMS
PPF"LOO
PPF"ORI.
PPINT
PPOP
PPRINR
PPRINT
PPRINU
PPUSH
PPUTCH
PPXRA

PRENT
PAESET
PRINBL.
PRINCO
PAINHA
PRINQU
PRINRE
PRINSE
PRINT
PRINTC
PRINTG
PAINTH
PRINTX
PAINUM
PRINVA
PAL.OOP
PRSUBR
PRTEMP
PATXRE
PSON
PSI<IPI
PSL.OOP
PSP'ACE
PSTICK
PSTOVA
PS)(ERR
PSYMTA
PTABDE
PTASF"L
PTASL.E
PT£N
PTEXT
PTI'OUT
PTAIN
PTUBIG
PUSERF'
PUSH
PUTCOF"
PUTCH
PUTCIN
PUTER
PUTJ
PUTL.CC
PUTI.P
PUTXRA
PxrORL
PXI.INB
PXXCRL
PXXEOF
PXXEXI
PXXL,IT
PXXTHE

0Ul7
6140
0471
6141
5676
121175
2461
0172
121204
3UJ3
2561
121037
121161
2563
3377
5175
141210
1514
1312
1441
5160
5161
0157
0122
2566
0144
0157
6742
3551
4434
3127
2776
6743
0117
0042
0043
12'044
12'045
121046
01121
0125
2565
4141
1760
6160
1105
2241
0114
1123
011214
1133
716~

23i6
013'
22'7
2303
2261
22~5

2242
23J2
~1 3
2217
2216
22!2
3712
37.'
36'3
37ii
3724
IUJ42
37t2
'615
i6!7
0116
15.,
01tl
01i2
0liu,
0115
5511
55'1
27'7
12114'
0"'6
7164
71'2
31121
5'45
2364
'1137
1741
'''23

'11'0
1'61
21'2
'1107
17'6
21"6
37~6

312'
2'64
3126
31S1
2'62

PieRDO ,5.'
QBIDL.E ;2"
QE"ROR 41;i
QHACHA 71'6
RANDAE ·14;i
R8SWCH 1135
REAO
1623
R[AOL.O 1'.6
READY
'5i5
REAL.Tl 74;3
REJECT 74'3
REL.ATE 13'2
REMPAC 3",43
RESETl 7116
RESET2 71.i
REITOR 3773
RETNEA 1113
RETURN
RHAL.r
311'.
RMLErT 6413
53;3
RNO
RNOJMP 53;'"
RTERR
73'3
RuBO
5573
RUN
2"2
RUN2IN 25'3
RUN2LU 25{4
RUN2NO 2537
RUNIN
2503
RUNLUP 2.65
RUNNOT 2';'
SC~MOR
1"7
seRATC 24.1
SEARCH 1"1
S[TCLO 74'3
SETRAT 7.;3
S[TSGN 4'12
SETUP
'.11
SGN
0'26
SIMPLY 3"6
SIN
"24
SINCHA 71'2
SJUMP
12.11
SKIPIT 14'7
SLASH
1332
SLOOP
27.7
SLSHTM 1331
SNUMrL. 11164
SPACER 13;1
SPECIN 12114m
SPL.ErT 11.4
SQ[XIT '451

1'"

SQLOOP
SQR
SSERR
SSF"IX
SSONE
SSTWO
STAR
START
STICI(I
STOP
STOVAR
SueR A
SXERR
TA8
TABOES
TABOO
TABF"LG
TABOI(
TABT~R

TAN
TB£G,.1
TEN
THESI(I
THISTX
TIM
TIMl
TIM2
T~p

TOOLON
TPRINT
TRAL.UP
TRANSF"
TRYAGI
TRYSTE
TST
TSTF"X
TSTP
TTYIN
TTYOUT
TU81G
TWIOTH
TWOSS
TXTPAK
Ull21
UlllJl2I
U11
U177
U1P
U2P
U411217
U5a11lJ
U7

5435
5412
1570
4775
0344
0345
1327
1000
6430
2570
0341
2161
6441
5547
6367
6350
2345
6360
2362
5600
5572
0000
1353
3107
7477
0Q104
00135
02131
5162
63721
2105
2103
5133
0626
7421
7417
7431
7173
1165
2657
2357
11lJ77
32146
212136
02113
01lJ47
02111
1503
1504
021221
121 IlJ 34
02133

U7760
U7767
U7775
U7777
UABAD
UAC1
UAC2
UAC3
UACCPT
UA,DCB
UADCIN
UADCMY
UADCN
UCLC
UCLOQP
UCLS
ueEVCO
UDOAD
UOOPER
UF"F"UD
UF'JMP
UGETWO
UGH1
uIEXT
UIEXT2
UIEXT3
UIEXT4
UlNAe
UJMP
UJMS
UMEVAI.
UMOPER
UNOERF'
UPAGET
UPARR2
UPARRO
UPARRX
UPCOMe
UPF'IX
UPF'UN
UPJMP
UREAL
UREJT
uSE
USERF"N
USETC
USETF"
USETM
USETR
USI<IPI
UTEMP
UTIM

UUAC1
UUAC2
UUAC3
UUOATA
UUOEVC
UUrUOG
UUJMP
UUJMS
UUMEVA
UUNOAD
UUftF"IX
UUSETF'
UUUJMP
UUUJMS
UUULLL
UVP
UWAIT
UWAITC
VA"
VARTEM

0052
0Q135
0Q121
0Q150
062"

02137

0040
0Q141
",453
0600
0613
0615
0622
0345
0217
0340
0Q156
0051
1363
121756
0757
02157
3562
0234
0243
0245
0260
1lJ631

VSC~lN

VSCHLU
VSCHNO
WAIT
WAITC
WOTEMP
WORD
XEXECU
XCISIT
XCMUST
xISIT
XMUST
XRESTA
XXABS
xxACPT
XXA08
XXAOC
XXATN
XXBSLS
XXCL.C
XXCLEA
XXCL.OS
XXCLS
X)(COMM
xxeos
XXCRL.F'
XXOATA
XXOEF
XXOEL.A
XXDIM
XXEG
xxEL.

02154

IlJI55
1lJ131
1321
4645
0653
4365
6457
5740
1lJ731
1132
0747
21136
0460
0456
7446
1620
1lJ411
0550
1lJ416
040a
,.61
0153
a'41

06'4
13661
13666
"'67
011'
131~'

O122
01i7
06'3
146O
06'7
00~0

0130
187tl
1lJ3~2

"12
0437
tlJ4~12I

0343
0"3
35t4
34'5
3,tllJ

'4'3
"'3

iI"

01'1lJ
1lJ412
41"
'34'
4"3

'312

1113
;1S4
'466
7223
'1'6
'ltllJ
72321
'221lJ
7486
'.'6
;215
"'2
71{2
'226
'3.3
'333
'412
'3~6

'1.6

'Itl

XxENO
XXEOF'
XXEQ
XXEXIT
XXEXP
XX'INI
XXF'N
XxF'OR
XX~E

XXGET
XXGOSU
XXGOTO
XX~T

XXIF"
XXINPU
XXINT
XXL.BFU
XXI.E
XXI.ET
XXI.IS
XXI.IST
XXI.ITI
XXL.OG
XXLPT
XXI.T
)(XMINU
XXNE
XXNEXT
XXNRUB
XXOPEN
xxflLOT
XXflLUS
XxflRIN
XX'TP
XXftTR
xxPUT
XXR8RA
XX~EAD
)(X~EAI.

XXfIt·[JT
XXfltEM
XXfltETR
XXfltNO
XXfltSTO
XXfltUB
XXfltUN
XXICR
XxSEMI
XXIETC
XX.ETR
XXIGN
XxllN

7Z32
7'82
7Q1;4
7,jS
;126
"14
71187
72S'
7Q1'QI
71;3
7241
72.6
'0.1lJ
7Z.IlJ
72'3
7142
'118'
7Q1S'
72'1lJ
71.2
'1;6
"i6
;123
13'1
,QI;,
712'
;143
72;.
73'7
1113
;~i2

'li3
7311lJ
13'4
13'7
11i3
71'i
;337
1~i6

7~;3

73i7
73ii,
71.'
73i2
13;2
7165
;l'i
''''4
, •• 3

;.35
;137
;1irl

XXSL.AS
XXSQR
XXSTAR
XX5TE:P
XXSTOP
XX,TA8
XXTAN
XX TEXT
XXTHEN
XXTIME
XXTO
XXTTV
XXTTVI
XXTTVO
XXUCOM
XXUNAR
XXUPAR
XXuSE
XXUUP'
XXWA1T
YYWA1T
i!ERDON
i!ERO
i!F'IXEX
i!i!ADB
i!i!AOC

7131
7131
7127
7176
7312
7217
7115
7511
72'3
7214
7172
7211
7347
73'4
7462
7513
7133
7416
7212
7452
7456
5144
rlJ152

4767
0775
rlJ770

STATEMENT AND COMMAND SUMMARIES
Summaries of the editing and program control commands
available in 8K BASIC are presented below.
Edit and Control Commands
Command

Abbreviation

Action

CTRL/C

Stops a running program. and
returns to the editing phase of
BASIC.

CTRL/O

Stops output of a running BASIC
program. Remains in this state
until BASIC requests INPUT, an
error occurs, or until another
CTRL/O is typed.

LIST

LIS

Lists the entire program in core.

LIS n

Lists line n through end of program.

NO RUBOUTS

Disables the RUBOUT key.

RUBOUTS

Enables the RUBOUT key.

RUN

Compiles and runs the program
currently in core.

SCRATCH

SCR

Erases the current program from
core.

BASIC Statements
Statement

Example of Form

DATA

DATA nl, n2,
... nn

Numbers nl through nn are to be
associated with corresponding variables in a READ statement.

DEF

DEF FNB (x) ==
f(x)
DEF FNB (x, y)
==f(x, y)

The user may define his own function to be called within his program by putting a DEF statement
at the beginning of a program. The
function name begins with FN and
must have three letters. The function is then equated to a formula
f(x) which must be only one line
long.

Explanation

Statement

Example of Form

DIM

DIM v(s)

Enables the user to create a table
or array with the specified number
of elements where v is the variable
name and s is the maximum subscript value. Any number of arrays can be dimensioned in a
single DIM statement.

END

Last statement in the program.
Signals completion of the program.

FOR-TOSTEP

FOR v==fl TO f2
STEP f3

Used to implement loops; the variable v is set equal to the formula
fl. From this point the loop cycle
is completed following which v is
incremented after each cycle by f3
until its value is greater than f2.
If STEP f3 is omitted, f3 is assumed to be + 1. f3 may also be
negative.

GOSUB

GOSUB n

Allows the user to enter a subroutine at several points in the
program. Control transfers to line

Explanation

n.
GOTO

GOTO n

Transfers control to line nand
continues execution from there.

IF-GOTO

IF fIr f2 GOTO n

Same as IF-THEN.

IF-THEN

IF fl r f2 THEN n

If the relationship r between the
formulas f1 and f2 is true, trans-

fers control to line n (n may also'
represent an operation); if not, continues in regular sequence.
INPUT

INPUT vI, v2,
... vn

Causes typeout of a ? to the user
and waits for the user to supply
the values of the variables vI
through vn.

LET

LET v==f

Assigns the value of the formula f
to the variable v.

LPT

Assigns line printer as output device.

NEXT v

Used to tell the computer to return to the FOR statement and
execute the loop again until v is
greater than or equal to f2.

Statement

Example of Form

Explanation

PRINT aI, a2,
... an

Prints the values of the specified
arguments, which may be variables,
text or format control characters
(, or ;).

PTP

Assigns high-speed paper
punch as output device.

tape

PTR

Assigns high-speed paper
reader as input device.

tape

READ

READ vI, v2,
... vn

Variables v I through vn are assigned the value of the corresponding numbers in the DATA string.

REM

When typed as the first three letters of a line, allows typing of
remarks within the program.

RESTORE

Sets pointer back to the beginning
of the string of DATA values.

RETURN

Must be at the end of each subroutine to enable control to be
transferred to the statement follQwing the last GOSUB.

STOP

Terminates execution at that point
at which the statement is reached
in the program.

TTY IN

Assigns a console terminal as input
device.

TTY OUT

Assigns a console treminal as output device.

During input to the editor or when executing an INPUT command, the following messages may be printed in response to
the input:
Message

Explanation

LINE TOO LONG

The line just typed exceeded the available core
buffer and must be retyped.

DELETED

The line has been deleted in response to an
AL TMODE character and must be retyped.
Back arrow is printed any time a RUBOUT or
SHIFT/0 is used. The previous character is
deleted.

TTY

BASIC prints TTY to indicate that there is no
more input from the high-speed reader and
that it is waiting for input from the Teletype.

appendix a
loading procedures

Initializing the system
Before using the computer system, it is good practice to initialize
all units. To initialize the system, ensure that all switches and controls are as specified below.
1. Main power cord is properly plugged in.
2. Teletype is turned OFF.
3. Low-speed punch is OFF.
4. Low-speed reader is set to FREE.
5. Computer POWER key is ON.
6. PANEL LOCK is unlocked.
7. Console switches are set to O.
8. SING STEP is not set.
9. High-speed punch is OFF.
10. DECtape REMOTE lamps OFF.
The system is now initialized and ready for your use.
Loaders
READ-IN MODE (RIM) LOADER
When a .computer in the PDP-8 series is first received, it is nothing more than a piece of hardware; its core memory is completely
demagnetized. The computer "knows" absolutely nothing, not even
how to receive input. However, the programmer can manually
load data directly into core using the console switches.
The RIM Loader is the very first program loaded into the computer, and it is loaded by the programmer using the console

A-I

switches. The RIM Loader instructs the computer to receive and
store, in core, data punched on paper tape in RIM coded format
(RIM Loader is used to load the BIN Loader descrJbed below.)
There are two RIM loader programs: one is used when the input is to be from the low-speed paper tape reader, and the other
is used when input is to be from the high-speed paper tape reader.
The locations and corresponding instructions for both loaders are
listed in Table A-I.
The procedure for loading (toggling) the RIM Loader into core
is illustrated in Figure A-I.
Table A-I.

RIM Loader Programs
Instruction

Location

Low-Speed Reader

High-Speed Reader

7756
7757
7760
7761
7762
7763
7764
7765
7766
7767
7770
7771
7772
7773
7774
7775
7776

6032
6031
5357
6036
7106
7006
7510
5357
7006
6031
5367
6034
7420
3776
3376
5356
0000

6014
6011
5357
6016
7106
7006
7510
5374
7006
6011
5367
6016
7420
3776
3376
5357
0000

After RIM has been loaded, it is good programming practice to
verify that all instructions were stored properly. This can be done
by performing the steps illustrated in Figure A-2, which also
shows how to correct an incorrectly stored instruction.
When loaded, the RIM Loader occupies absolute locations 7756
through 7776.
A-2

SET SWITCHES 6-8
TO DESIRED
NSTRUCTION FIELD*

*DECTAPE USERS SHOULD
LOAD RIM INTO FIELD 0

.Figure A-I.

Loading the RIM Loader

A-3

SET SWITCHES
6-8 TO FIELD IN
WHICH RIM HAS
8EEN LOADED

Figure A-2.

Checking the RIM Loader

BINARY (BIN) LOADERThe BIN Loader is a short utility program which, when in core,
instructs the computer to read binary-coded data punched on paper
tape and store it in core memory. BIN is used primarily to load the
programs furnished in the software package (excluding the loaders
and certain subroutines) and the programmer's binary tapes.
BIN is furnished to the programmer on punched paper tape in
RIM -coded format. Therefore, RIM must be in core before BIN
can be loaded. Figure A-3 illustrates the steps necessary to properly load BIN. And when loading, the input device (low- or highspeed reader) must be that which was selected when loading RIM.
A-4

- - - -1

Figure A-3

See FIOU"I' C2-1.C2-21

Loading the BIN Loader

A-5

When stored in core, BIN resides on the last page of core, occupying absolute locations 7625 through 7752 and 7777.
BIN was purposely placed on the last page of core so that it
would always be available for use-the programs in DEC's software package do not use the last page of core (excluding the Disk
Monitor) . The programmer must be aware that if he writes a
program which uses the last page of core, BIN will be wiped out when that program runs on the computer. When this
happens, the programmer must load RIM and then BIN before
he can load another binary tape.
Binary tapes to be loaded should be started on the leader-trailer
code (Code 200), otherwise zeros may be loaded into core, destroying previous instructions.
Figure A-4 lilustrates the procedure for loading binary tapes
into core.

A-6

- - ~ SEE FIGURE C2-31

F:gure A-4.

Loading A Binary Tape Using BIN

A-7

appendixb
character codes
ASCII-I! Character Set
8-Bit
Character Octal

6-Bit
Octal

301
302
303
304
305
306
307
310
311
312
313
314
315
316
317
320
321
322
323
324
325
326
327
330
331
332
260
261
262
263
264
265
266
267
270
271

01
02
03
04
05
06
07
10

A
B
C
D
E
F
G
H
I
J

K
L
M
N

a
P

R
S
T
U
V
W

X
Y
Z

0
1
2
3
4
5
6
7
8
9

12
13
14
15
16
17
20
21
22
23
24
25
26
27
30
31
32
60
61
62
63
64
65
66
67
70
71

Decimal
Equivalent
(AI Format)

Character

96
160
224
#
288
$
352
%
416
&
480
544
(
608
)
672
*
736
+
,
800
864
928
992
/
1056
1120
1184
<
1248
1312
>?
1376
1440
@
1504
[
1568
1632
]
1696
t(A)~
~(-):!
·-992
Leader/Trailer
-928
LINE FEED
-864
-800 Carriage RETURN
SPACE
-736
RUBOUT
-672
Blank
-608
BELL
-544
TAB
-480
FORM
-416

8-Bit
Octal
241
242
243
244
245
246
247
250
251
252
253
254
255
256
257
272
273
274
275
276
277
300
333
334
335
336
337
200
212
215
240
377
000
207
211
214

Decimal
6-Bit Equivalent
Octal (AI Format)
41
42
43
44
45
46
47
50
51
52
53
54
55
56
57
72
73
74
75
76
77
33
34
35
36
37

-1952
-1888
-1824
-1760
-1696
-1632
-1568
-1504
-1440
-1376
-1312
-1248
-1184
-1120
-1056
-352
-288
-224
-160
-96
-32
32
1760
1824
1888
1952
2016

-2016

1 An abbreviation for American Standard Code for Information Interchange.

2 The character in parentheses is printed on some Teletypes.

B-1

INDEX

AC1, 44
AC2, 44
AC3, 44
Acceptable nesting
techniques, 25
ACE, 44
ACS, 44
Addressing, 45
Indirect relative, 47
Relative, 45
ALTMODE, 54
ANORM, 48
Argument, 36
Arithmetic operations, 3
Priority of, 4
Arithmetic statement, 10
Array, 25
Maximum size of an, 28
ASCII character set, B-1
Backslash, 9
BASIC compiler, 58
BEGFIX, 48
BIN loader, A-4
loading the, A-5
loading a binary tape,
A-7
BKWD, 45
Character codes, B-1
Character set, B-1
Characters,
Format control, 15
Checking the RIM loader,
A-4
Coding formats (UUF), 43
Command,
LET, 6
LIST, 55
LPT, 55, 57
PRINT, 6
PTP, 55, 57
PTR, 56
RUN, 56
SCR, 58
Command summary, 67
Commands,
Editing and Control, 53,
67
Commenting the program, 9
Conditional transfer, 24,
30
Control characters,
Format, 15
Control commands,
Editing and, 53, 67
CTRL/C, 36, 57
CTRL/O, 57

DATA statement, 11
DEF statement, 42
Devices,
I/O, 22
DIM statement, 27
Directing program control,
29
Dummy variable, 13, 39, 42
E-type notation, 2
Editing and Control
commands, 53, 67
END statement, 9
Equal sign,
Meaning of the, 5
Erasing a program in core,
58
Erasing characters and
lines, 53
Error messages, 59
Evaluation,
Order of, 4
Example Program, 7
Examples (UUF), 48
Exponential notation, 2
FAC, 44
FENTER, 44
FEXIT, 44
Field, 24
FIX, 48
Floating accumulator, 44
Floating-point format, 44
Floating-point instruction
set, 45
Floating-point interpreter,
45
Floating-point package, 43
FNA function, 42
FOR statement, 22
Format control characters,
15
comma, 16
semicolon, 17
Fo~ats, coding (UUF), 43
Formatting output, 41
Formula, 22, 24
Function, 34
FNA, 42
GET, 39
INT, 35
PUT, 39
RND, 36

SGN, 35
TAB, 36
User-defined, 59
UUF, 43
Functions, 34
FWD, 45

X-I

Generating random numbers
over any range, 37
GET function, 39
GOSUB nesting,
maximum level of, 33
GOSUB statement, 30, 31
GOTO statement, 29
I/O devices, 22
IF GOTO statement, 30
IF THEN statement, 30
Immediate mode, 6
Incremental value, 22
Index, 22
Indirect relative
addressing, 47
Initial value, 22
Initializing the system,
A-l
INPUT statement, 14
Input/Output statements, 11
Instruction set,
Floating-point, 45
INT function, 35
Integer function, 35
Introduction, 1
LET cormnand, 6
LET statement, 10
Level of GOSUB nesting, 33
List, 25
LIST command, 55
Listing and punching
program, 55
Loaders, A-l
Loading a binary tape
(using BIN), A-7
Loading and operating
procedures, 58
Loading procedures, A-l
Loading the BIN loader, A-5
Loading the RIM loader, A-3
Loops, 22
Nesting, 24
LPT command, 55, 57
LPT statement, 19
Mass storage devices, 47
Maximum level of GOSUB
nesting, 33
Maximum size of an array,
28
Meaning of the equal sign,
5

Minimum system
configuration, 1
Mode,
Immediate, 6

Nesting loops, 24
Nesting subroutines, 33
Nesting techniques,
Acceptable, 25
Unacceptable, 25
Nesting, maximum level of
GOSUB, 33
NEXT statement, 22, 23
NO RUBOUTS, 53
Normalized form, 44
Numbers, 2
Operating procedures,
Loading and, 58
Operators, 3
Relational, 5
Order of evaluation, 4
Output,
Formatting, 41
Parentheses, 4
PRINT command, 6
Print positions, 37
PRINT statement, 15
Print zones, 16
Priority of arithmetic
operations, 4
Program control,
Directing, 29
Programming errors, 60
PTP command, 55, 57
PTP statement, 20
PTR corranand, 56
PTR statement, 14
PUT function, 39
Random number function, 36
READ statement, 11
Reading a program, 56
Relational operators, 5
Relative addressing, 45
Indirect, 47
REM statement, 9
RESTORE statement, 12
RETURN, 54
RETURN statement, 31
RIM, A-l
RIM loader,
Checking the, A-4
Loading the, A-3
RIM loader programs, A-2
&~D function, 36
Rounding numbers, 36
RUBOUT, 53
RUN cormnand, 56
Running a program, 56
SCR command, 58
SGN function, 35
SHIFT/L, 9

X-2

SHIFT/O, 53
Sign function, 35
Sign-magnitude convention,
43

Statement,
Arithmetic, 10
DATA, 11
DEF, 42
DIM, 27
END, 9
FOR, 22
GOSUB, 30, 31
GOTO, 29
IF GOTO, 30
IF THEN, 30
INPUT, 14
LET, 10
LPT, 19
NEXT, 22, 23
PRINT, 15
PTP, 20
PTR, 14
READ, 11
REM, 9
RESTORE, 12
RETURN, 31
STEP, 23
STOP, 10
TTY IN, 20
TTY OUT, 20
Statement numbers, 8
Statement summary, 67
Statements, 7, 67
Input/Output, 11
Transfer of control, 29
STEP statement, 23
STOP statement, 10
Stopping a run, 57
Subroutines, 30
Nesting, 33

Subscript, 27
Subscripted variables, 22,
25
Summary,
Command, 67
Statement, 67
Supported options, 2
Symbol Table, 62-66
System configuration,
minimum, 1

TAB function, 36
Table,
Symbol, 62
Terminal value, 22
Terminating the program, 9
Transfer,
Conditional, 24, 30
Unconditional, 29
Transfer of control
statements, 29
TTY IN statement, 20
TTY OUT statement, 20
Two-dimensional matrix, 26
Unacceptable nesting
techniques, 25
Unconditional transfer, 29
User-defined function, 59,
43

UUF function, 43
Variable, 3
Dummy, 13, 39, 42
Subscripted, 22, 25
Writing the program, 47

X-3

8K BASIC
DEC-08-LBSMA-A-D
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