IBM Series 1 User Manual page 239

TNL: GN34-0368 to GA34-0033-0 (February 4, 1977)
write Control. A Write command has the following format:
Bits 0-3
0101
Bits 4-7
OOOX
Bit 7 of a Write command controls the Write Control
output. If a Write command is issued with bit 7=1, the Write
Control output will close and remain closed until either (a)
a Write command is issued with bit 7=0, or (b) the attach-
ment is reset.
If a Write command is issued with bit 7=0, the Write
Control output will open and remain open until a Write
command is issued with bit 7=1.
Any system reset or device reset will cause the Write
Control output to open and remain open until a Read command
is issued with bit 7=1.
A Write command can change the state of the Write
Control output if the
010
condition code response to the
command is condition code 1 (write busy) or 7 (command
accepted) .
A Write command cannot change the state of the Write
Control output if the
010
condition code response to the
command is condition code
0
(device not attached),
3
(command reject), or
5
(interface data check). The Tele-
typewriter attachment does not use condition codes 2, 4,
or 6.
Write Control Timing. The Write Control output can change
state only during the first 0.2 microsecond of the start bit
of a transmit operation. It will be opened by a system reset
or device reset.
4-16.2 GA34-0033
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