RCA 301, Programmer'S Reference Manual

Page: 107 / 235

S Input/Output Sense (IOS)
General Description
This instruction tests the desired status of the selected card device and chooses one of two sequences of
instructions.
Format
Operation — S
N
— Selects the card device to be tested according to the following:
Device
N
Card Reader or Read Unit of Card Reader-Punch
(
Card Punch or Punch Unit of Card Reader-Punch
)
A Address — A
0
specifies the tests to be performed as follows:
"1" Bit
In
Numeric
Equivalent
Tests
2°
2
1
1
2
Is the selected device inoperable?
Is the selected device operating?
— A,, A
2
, A
3
— Must be zeros (000).
B Address — HSM location of the next instruction to be executed if the condition or conditions being tested
are present.
Standard Location
STP (on transfer only)
Outline of Operation
The test (or tests) called for by the one bits in A„ are performed on the device selected by N. If any one of the
conditions tested is present, the contents of the P Register are transferred to STP and the contents of the B Register
are then transferred to the P Register. If no tested condition is present, the next instruction in sequence will be
executed.
Final Register Contents
(A)
f
— (A) ,
( B )
f
= ( B ) ,
Timing
56 ^s if a transfer is executed.
42 fxs if no transfer takes place.
VIII-21