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PSI BOX Reference
software the length of the control status string increases. It is
advised that 256 bytes of space are set aside for the IEEE
control status string in your program to allow complete
compatibility with future version of the Mode 7 software. The
format of the data returned is given in below.
_____________________________________ _
Figure 7-2 The IEEE Control Status String.
BYTE RANGE FIELD DESCRIPTION.
____ _____ __________________
1-2
00-30
4-5
00-30
7
0 or 1
9
0 or 1
11
0 or 1
13-14 00-15
16-2 000000-65535 The number of bytes read from bus on last input.
22-26 00000-65535 The number of bytes sent to the bus on last output.
28-30 000-255
32-34 000-255
36-38 000-255
40
0 or 1
42
0 or 1
44-46 000-255
48
0-9
50-51 00-30
53-54 00-30
56-57 00-30
59-61 000-255
63-64 00-15
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Current device IEEE device number
Current device IEEE secondary address. SPACE SPACE
means no sa.
SRQ input line. 1 means SRQ is asserted true by a
device so requesting service.
ATN output line. 1 means that PSI BOX is the active
controller asserting attention.
REN output line. 1 means that the PSI BOX is
asserting REN true. Devices under IEEE control.
IEEE bus status field. 4 bits each representing a
particular state. Bit0 = time out on o/p, bit1 =
time out on i/p, bit2 = EOI/EOS on i/p, bit3 = no
device present.
The SERIAL POLL data for the current device,
current device address as in bytes 1-2.
The SERIAL POLL data for the first device addressed
in the previous SPOLL command.
The PARALLEL POLL data from the previous parallel
poll command.
ON SRQ flag. 1 means an ON SRQ has been auto-
matically performed since IEEE data was last read.
IEEE control data syntax error. 1 means the
previous BUS string written to the PSI BOX
contained an error.
Syntax error byte. This is the position of the
first byte in the previous BUS command that the PSI
BOX did not recognise. Starts counting from the B
in BUS as 1.
ECHO flag. 0 is the default ECHO=OFF. 1 is ECHO=ON.
MLA. The MY LISTEN ADDRESS of the PSI.
MSA. The MY SECONDARY ADDRESS of the PSI. SPACE
SPACE means no MSA.
MTA. The MY TALK ADDRESS of the PSI.
Debug field .. reserved.
The current time out value. 00= wait for ever till
device is ready.
Mode 7 Overview
Chapter 7
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