PSI BOX Reference
Modes 1-6 & 8.
The Mode 1+2 IEEE Handshake.
_____________________________
The controlling computer needs to address the PSI BOX as
a listener or a talker, at the end of a data transfer sequence the
PSI BOX should be un-addressed by the unlisten or the untalk
command. When the PSI BOX is a listener, receiving data, it
recognises that EOI is the end of stream terminator. When
addressed to talk the PSI BOX uses EOI to flag the end of its
data stream to the controller.
In modes 1 and 2 the Data transfer to the IEEE port from the
controlling computer is:
PSI BOX listen address, from IEEE controller computer.
Data bytes.. from IEEE controller computer.
Last data byte + EOI from IEEE controller computer.
Unlisten, from IEEE controller computer.
In modes 1 and 2 the Data from the IEEE port to the controlling
computer is:
PSI BOX talk address, from IEEE controller computer.
Data bytes.. from PSI.
Last data byte + EOI from PSI box.
Untalk, from IEEE controller computer.
The Mode 1+2 Secondary Addresses.
________________________________
When working in Mode 1 and Mode 2 the IEEE port
recognises several secondary addresses.
The IEEE device number, the IEEE primary address, of the
PSI BOX is as set on the front panel DIP switches. Secondary
addresses are specified in the OPEN statement that is sent from
the CBM PET computer or HP computer. By requesting or
sending data using these special secondary addresses the PSI
Box can communicate its status and other information to the
IEEE controlling computer. The secondary address in use are as
follows:-
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Chapter 6
