IBM Series 1 - Page 20

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The I/O Channel signal lines can be subsetted depending upon
the level of fU,nction reguired by the I/O att.achment. In
order of increasing level of function, these subsets are:
• Basic subset
• Interrupt subset
• Cycle Steal/IPL subset
Attachment to a subset is a prerequisite for attachment
to the next higher level subset.
The basic subset consists of the busses and tags to support
functions initiated by the processor; that is, DPC (direct
program control) commands. This includes the data transfers
associated with the ope command itselt. The basic subset
supports DPC devices that do not interrupt.
The I/O signal lines in the basic subset are listed in
Figure 2-3.
Figure 2-3 (Part 1 of 2).
~asi£ Subset--Ser.!i~ GrQ'!!£ ~~gn~l 1in~
Address bus bit
Address bus bit
Data bus *2
Address gate
00-15 *1
16
Address gate return
Condition code in bus
Da ta strobe
Halt or MCHK
System reset
Power on reset
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<------
<------
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16
1
18
1
1
]
1
1
1
1
Processor I/O Channel 2-5