Address Mirroring Disab1E/Enable - Vector ZCB User Manual

Vector ZCB Single Board COJ.Tq?uter
2.4.2 Address mirroring disable/enable
Jumper area 0
connections as manufactured: function enabled: pad 3 connected to pad 2
Function: emulates 8080 address mirroring: 8-bit I/O port address is mirrored
on the high address bus during an I/O instruction.
Options: To disable address mirroring, cut the jumper between pads
3
and
2
and
jumper I and 2 together. 'Ibis will place the I/O device address on the lower
half of the address bus am the value of the contents of the accumulator on the
upper half of the address bus during a direct I/O instruction. During indirect
I/O instructions (including block moves), the value of the contents of register
C is placed on the lower half of the address bus (device address) while the
value of the contents of register
B
is placed to the upper half of the address
bus.
Rev. I-B 6/11/80
2-9