PSI BOX PLUS+ Reference
Control Functions
CMD.
Send A Byte With Attention True.
______
______________________________
Purpose.
To send a command byte to the IEEE bus.
__________
CMD is available for the user to send any bytes he wishes
to the IEEE bus, with the ATN line asserted. This means that
the byte is interpreted by the devices as a command rather than
as a data byte. This command is the complement to DATA
which sends a byte with ATN false.
This routine can be used to send any of the standard IEEE
commands. The user must ensure that he has got the sequence of
commands and secondary commands correct.
The PSI BOX asserts ATN, if not already true, and
becomes the active controller
Use NO ATN to drop ATN false again when you have
finished sending your stream of commands.
The bit 7 of the byte values sent is a don’t care bit, but are sent
as entered.
Format.
CMD byte
_________
Params.
One or some.
_________
Returns.
None, ATN is left true.
__________
Example.
________
_
BUS CMD 32 33 63
:REM ISSUE COMMAND
Bus Activity.
___________
_
assert ATN if not already so
LISTEN 0 (=command 32)
LISTEN 1 (=command 33)
UNLISTEN (=command 63)
CMD Equivalents Of IEEE Bus Commands.
______________________________________
_
1 or 129 GTL GO TO LOCAL.
4 or 132 SDC SELECTIVE DEVICE CLEAR.
5 or 133 PPC PARALLEL POLL CLEAR.
8 or 136 GET GROUP EXECUTE CLEAR.
9 or 137 TCT TAKE CONTROL.
Page 90
Chapter 8
