RCA 301 Programmer's Reference Manual page 46

Description of Instructions
Information pertaining to each instruction is described under the headings as given below. Special explanation
for some of these is also included.
Instructive Symbol (OP Code)
Name and Abbreviation of Instruction
Repeatable (if applicable)
General Description
Format of Instruction
Direction of Operation
Standard Location, if used
Outline of Operation
Final Registers Contents
PRI settings (where applicable)
Timing
Example
DIRECTION OF OPERATION
A Direction of Operation subsection appears in all applicable instructions and defines the direction of operation
in HSM.
OPERATION
An Outline of Operation subsection supplements the General Description prefacing the instruction. Internal
logic is described not in every detail, but only to the extent that it contributes to the attainment of the objectives
of a programmers' reference manual: (1) to help the programmer gain a better understanding of Computer operation,
(2) to permit the programmer to modify the instructions and their application for individual problem solution and
(3) to enable the programmer to develop advanced programming techniques.
TIMING
Due to the variable item length concept in the RCA 301 System, instruction times can be expressed only as a
function of the number of characters involved in a given operation. For example, the time required to write out to
tape depends on the number of characters to be written, and the time required to add two numbers together depends
on the number of digits in the operands.
The time, or timing formula, listed for each instruction includes staticizing time, and STA or STP where
applicable. Indirect addressing requires an additional 14 microseconds per indirect address.
Each time a repeatable instruction is repeated there are three additional status levels (21 microseconds) required
when the contents of the N
when the N (Repeat) Register contents are zero.
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EXAMPLES
Wherever possible, the examples that accompany the instruction include representation of the unaffected portion
or portions of the High-Speed Memory. The content of the HSM locations are shown by bit values in some of the
instructions and as alphanumeric characters in other instructions.
In each example, the subheading "HSM before Instruction is Executed" is to be interpreted as before execution
but after staticizing. The contents of the memory locations are not affected by staticizing. The initial register settings
of A,, Bi, T Si however, reflect register contents after staticizing.
i(
IV-2
(REPEAT) Register exceed zero, and one additional status level (7 microseconds)
R