Specifications

Theory of Operation
BOARD SELECT OPTION
A ZT 8832 occupies 32 Kbytes of STD bus memory address space
and 16 bytes of STD bus I/O address space. The memory is jumper
selectable to any 32 Kbyte block and the I/O is jumper selectable to
any of 16 possible locations. Systems using multiple ZT 8832s can
map each one to a unique memory and I/O address range. However,
in some systems this may not be possible because of limited STD bus
resources. The board select option solves this problem by reducing
the memory and I/O requirements of up to seven ZT 8832s to those of
a single ZT 8832; up to 14 ZT 8832s to those of two ZT 8832s; and
so on.
Follow the steps listed below to begin using the board select option.
The mapping options discussed below are found in the jumper table
beginning on page A-2.
1. Map the dual port RAM of each ZT 8832 to the same STD bus
memory addressing range.
2. Map the STD bus control port, board select port, and interrupt
status port of each ZT 8832 to the same STD bus I/O address
range.
3. Jumper program a unique board select address for each
ZT 8832. Please note that with three jumpers there are eight
combinations. One combination is used to disable the board
select feature, leaving seven unique combinations for up to
seven boards.
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