RCA 301, Programmer'S Reference Manual, Page: 170 / 235

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5 Tape Read Forwar d Simultaneous (RFS)
General Description
This instruction is used to receive data into the HSM of one processor from the HSM of another processor
provided both are equipped with a Data Exchange Control. This instruction operates in the Simultaneous Mode.
Receipt of data will terminate when the terminate signal is received from the sending computer or by AB equality.
Format
Operation — 5
N —H (first unit)
I (second unit)
A Address — Location in HSM which is to receive the first diad transferred. This address must be even.
B Address — Location in HSM which is to receive the last diad transferred. This address must be even.
Direction of Operation
Left to right.
Outline of Operation
Same as the Tape Read Forward Simultaneous instruction (pg. IX-6) with the following exceptions:
1. The EF/ED Simultaneous Indicator is not affected.
2. When this instruction is staticized, a flip-flop is set in the sending computer which, when sensed, will
indicate that this computer is in the receive mode.
3. All characters received by the Data Exchange Control are checked for correct parity. If a character
with incorrect parity is received, octal 57 is substituted for it and placed in HSM, the IOS flip-flop
(Ao
23)
is set in each Data Exchange Control, and data transmission continues.
4. This instruction is terminated by AB equality or by receipt of a terminate signal from the sending
computer.
Final Register Contents
If the instruction is terminated by AB equality:
(S)i = (B), + 2
(T)
f
= (B)j
If the instruction is terminated by receipt of the terminate signal:
(S)
f
= (A)[ + the number of characters transferred + 2.
(T)
t
= (B),
Timing
The data transfer rate is dependent upon the mode in which the transfer is made and the availability of status
levels in both processors.
XIII-4