Arcom SC88T, Техническое руководство

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Section 5. I/O Devices
The chip-selects for I/O devices are generated by the 80188, and it is vital to set
the 80188 up in software as part of the initialisation sequence. If this is not done
the board will not function correctly. See section 7 for information on how to do
this.
There are three types of I/O devices which the 80188 can access.
1. I/O boards on the STEbus
The STEbus 4k I/O space is accessed in the lower 32k of the 80188’s 64k I/O
address space. The selection is automatic, and the programmer should not
relocate any of the programmable I/O chip selects in this space.
2. The on-board SCC for serial communications
The on-board SCC is controlled by two programmable chip-selects. PCS1 is the
chip-select which accesses the registers. Accessing PCS2 will assert INTA*, the
SCC interrupt acknowledge input. This must be done to acknowledge the SCC
interrupt generated on INT2 of the 80188, because the 80188 in its most useful
interrupt mode does not generate an acknowledge. A read from PCS2 will read
the interrupt vector from the SCC and reset the SCC ready for the next interrupt.
3. The 80188 on-chip peripherals (counter/timers, DMA etc)
These integrated peripherals (and the address of PCS1 and PCS2) are controlled
by the Internal Control Block. Even the I/O base location of this block of
peripherals is controlled by the relocation register within the block. It is
recommended that you do not alter this block unless you are sure what you are
doing.
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J90 SC88T 2192-08819-000-000