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Error Recognition - RCA Spectra 70 Training Manual

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PRINTER Control Byte
;!
l
=
COUNT
23
2
1
o
1
NOT USED
Examples
of
Write Control
Advance the paper up to fifteen
single spaces, or selection of
Paper Tape Loop
Channel
(1-11) .
Paper advance following next
print action.
Paper advance immediately.
Paper advance by 2 0 -22 count.
Paper advance by Paper Tape
Loop as selected by the 2 0 -22
count.
Assuming the following bytes in memory:
CTL1
CTL2
CTL3
00000001
00001000
01000010
(01)16
(08h6
(C2)r 6
The instructions: (Base Addresses implied)
NAME
OPERATION
OPERAND
WRC
1(1) , CTL1, CTL1
WRC
4(3) , CTL2, CTL2
WRC
3(1), CTL3, CTL3
will:
51
1.
Select Output Stacker #1 on the Card Reader
2.
Unwind one gap on Magnetic Tape 3
3.
Advance the paper on the printer two lines im-
mediately.
ERROR RECOGNITION
An error condition that develops during the execution
of an I/O instruction does not halt the computer.
If the selected device is busy the instruction is
~
staticized until the device is available. I/O instruc-
tions set the Condition Code to one of three conditions.
If the device is inoperable, the instruction terminates
and the Condition Code is set to one (1). If the in-
struction has been accepted for execution by the Con-
trol Electronics, the Condition Code is set to zero
(0), and the normal mode is free to staticize the next
instruction in sequence. If an interrupt is pending
on a device, and an instruction selects that device,
the instruction terminates and the Condition Code
is set to (2).
Note:
If inter rupt is inhibited on an I/O channel, the
termination interrupt generated by the end of
a command using that channel, will be pending
and the channel will remain busy until a Post
Status Instruction resets the busy bit in the
Control Electronics.

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