RCA 301, Programmer'S Reference Manual

Page: 133 / 235

S Input/Out put Sense (IOS)
General Description
This instruction tests the desired status of the selected printer and chooses one of two sequences of instructions.
Format
Operation —S
N — Selects the printer to be tested according to the following:
Device
N
Device
Unit #1
Unit #2
On-Line Printer
7
G
A Address — A
0
specifies the tests to be performed as follows:
Device
"1" Bit
Numeric
Tests
Device
In
Equivalent
Tests
On-Line Printer
2°
1
Is the selected device inoperable?
(Unbuffered)
2
1
2
Is a line being printed?
2
4
&
Is the paper advancing?
On-Line Printer
2°
I
Is the selected device inoperable?
(Buffered)
2
1
2
Is the printer busy? (This indicator is set at the
start of buffer loading and remains set through
completion of the last scan. It is also set when
the printer cover is open.)
2
2
4
Is the low paper flip-flop set? (Has end of paper
supply passed the low paper photocell?)
2
4
&
Is the paper advancing?
— A
1;
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
0
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), = (B)i
Timing
56 ju.s if a transfer is executed.
42 fj.s if no transfer takes place.
X-7