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The Coding Sheet
The General Assembly Program coding sheet is divided into six fields: symbol, operation,
operand, X, remarks, and sequence. The numbers 1- 80 in the header information on each sheet
correspond to the column numbers of a standard 80-column punched card. When a symbolic
program is punched into cards, columns
7
and 21 are not used; these blank columns separate
fields used in the program assembly.
SYMBOL FIELD
Columns 1-
6
constitute the symbol field.
Symbols may consist of from 1 to
6
characters. At
least,
one of the characters in the symbol field must be alphabetic. HOPE and CONST3 are
legitimate symbols; 345 is not a legitimate symbol.
A symbol may be either to the right or
left in the symbol field; that is, the symbol AB in columns 1 and 2 is the same symbol as AB
in columns
5
and
6.
The plus and minus signs cannot be used in the symbol field, because· they
are used in the operand field for relative addressing. A blank (space) in the symbol field is
ignored by the General Assembly Program assembler:
OPERATION FIELD
Columns 8, 9, and 10 make up the operation field. Any of the mnemonic codes for the normal
computer instructions (LDA, BRU, etc.) or for the pseudo-operations (ORG, DEC, etc.) can be
placed in this field. An invalid mnemonic causes an error notation during assembly.
OPERAND FIELD
Columns 12 - 19 constitute the operand field.
Operands may be alphabetic or alphanumeric
symbols up to six characters in length or a decimal number, and can be positioned anywhere
in the operand field.
A
single asterisk may be placed in this field to denote reference to this
instruction address.
(This is equivalent to writing the same symbolic name in both the symbol
and operand fields on one line.)
Symbols may also consist of arithmetic combinations not to
exceed eight characters of sums and differences of numbers, symbols, and asterisks. Arithmetic
expressions permit relative referencing to a specified symbol (for example, *-1 which means
self minus one) to reduce the number of symbols used. The plus and minus signs are used only
in the operand field and only when expressing a relative address or a signed constant. The
subject of relative addressing is discussed later.
All numbers appearing in the operand field
are considered to be decimal except when following the operation OCT, ALF, LOC, and EQO.
Numbers following OCT,
LOC, and EQO are assumed to be octal and are converted to their
binary equivalent.
Digits following ALF are converted to their binary-coded decimal (BCD)
equivalents.
Blanks (spaces) in the operand field are ignored, unless they follow the operation
ALF or NAL.
X
FIELD
Indirect addressing is specified by an X in column 20.
If
a character other than a blank appears
in column 20, the General Assembly Program inserts the indirect address bit into the absolute
instruction word being assembled.
However, if the character in the X field is not an "X" or a
blank, an error will be flagged by the assembly program. A blank in column 20 indicates that
no indirect addressing is to be performed.
[IDruu&~~uc:J ~®------------
V-63
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