INTRODUCTION TO THE RCA 70/25
Assembly is an automatic program-
ming system designed to translate a
machine-oriented program into a machine-coded
program for subsequent execution on the RCA
system. The source language consists of one-line
statements written on the RCA Spectra
Program Form. Each single-line statement per-
forms one of the following functions:
Generates an object program instruction.
Allocates data areas or constants.
Notifies the assembler to perform a specific
Every statement, except a line used solely for an
output listing comment, must have an entry in the
OPERATION field (Cols.
specifying one of
the above three functions.
The NAME field (Cols. 1-6 only) may be used when
it is desired to symbolically identify the leftmost
location of the field generated by the statement. The
NAME entry symbol must consist of at least one
alphabetic (A-Z) character followed by any combina-
tion of alphabetic and/or numeric
that do not exceed a total of six characters. The
only exception to the symbol entry above is that an
asterisk may appear in Col.
the statement line
is to be used for an output listing comment.
The OPERAND field has entries as required by the
OPERATION field. Thus, if the OPERATION field
specifies that a constant is being defined,
OPERAND field entry is the value of the constant.
If an instruction Operation Code appears,
OPERAND field must follow the prescribed format
for that particular instruction.
A comment may appear in any statement line fol-
lowing the OPERAND entry. It must be separated
from the required OPERAND entry by at least one
blank column. The entire statement line (to Col. 71)
may be used for a comment if an asterisk appears
in Column 1.
The contents of the IDENTIFICATION field has two
functions. In the START statement, the first four
may contain a name to be
assigned to the object program. If the last four
are numeric, the contents
is used as the initial setting ofthe Assembly sequence
counter. If not numeric, the counter starts at all
Each object instruction has a sequence
number either derived from the value in columns
or from zeros.
A symbolic name is the most frequently used means
of addressing and referencing a location.
symbol has been used in the NAME field to define a
may be referenced as frequently as de-
sired in the OPERAND field. The value assigned is
the address of the left end of the data field or in-
struction on the 'NAMEd' line of assembly coding.
As stated previously, the symbol may be any com-
bination of the alphabetics (A-Z) or numerics
There are two restrictions:
no name may exceed
the first character must be al-
The following are examples of valid and invalid
(Space invalid character)
(Too many characters)
(First character not alphabetic)
(Period invalid character)
The Assembler builds a table containing all the
symbolics that appear in the name field. A specific
HSM address is assigned to each symbolic. The
LOCATION COUNTER, a program counter main-
tained by the Assembler, generates these addresses
and makes assignments. Assume a routine is to
begin at HSM location