- (address bus) /MREQ, /IORQ, /RD, /WR, /RFSH, /M1, /WAIT, /HALT, /INT, /NMI, /
BUSRQ, /RESET (Z80
control signals) /BAI, /BOA /BUSACK (bus
priority chain) /IEI...
- Out CPU
status 40
STATUS 0 Out CPU
status 41
BUSAK Out Bus
acknowledge 42
BUSRQ In Bus
request 43
INTAK Out
Interrupt acknowledge 44
INTRQ In Interrupt...
- 74LS688 can
decode A11...4 to
locate I/O
slave boards at 16-byte boundaries.
BUSRQ/ and BUSAK/: Bus
Requests and Bus Acknowledge. Optional, used by multi-master...
- ADRSTB* Tri-state DATSTB* Tri-state DATACK* Open
collector / Open
drain BUSRQ[1..0]* Open
collector / Open
drain TFRERR* Open
collector / Open
drain ATNREQ[7...
-
other machines of the time, was to
temporarily stop the CPU
using the "WAIT/
BUSRQ" (Z80) "WAIT" (6809) or "SYNC" (6502)
control signal whenever the CPU tried...
