IBM Series 1 User Manual page 90

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PROCESSOR I/O CHANNEL PHYSICAL CHARACTERISTICS
This section presents I/O pin and cable assignments for all
standard channel signals, voltages, and special reserved
lines. It also provides basic data for the basic physical
components of the channel.
Sig~l ~in ~~
Cable Assignmeo!§
Figures 2-28 and 2-29 list all I/O channel and special lines
and their corresponding pin and cable assignments.
Figure 2-28 defines the signal lines with their
corresponding cable assignments and the I/O pin assignments.
Figure 2-29 defines the voltage/ground/special pin
assignments and gives a comparison between a typical I/O
slot position and the A-slot position. The corresponding
I/O cable pin assignments are also given in this table.
When connecting to an I/O expansion unit, four standard
I/O
channel cables must be used in order to obtain all signal
lines. These cables leave the 4955 processor unit via the
A-socket position on the board or via a repover card
contained on the board, depending on the configuration. The
4953 processor unit can only be cabled out via a repower
feature. In an I/O expansion unit, socket-A is restricted
for use as the entry point for the I/O channel cables.
Each cable carries twenty signal lines. They are
arranged in such a way that cable .1 plugs into the top of
tbe A-socket and cable'4 plugs into the bottom of the
socket.
Processor I/O Channel 2-75