Compuprint 9058 Programmer Manual User Manual
Page 138
The Parallel Interface
A78408098-003
C.9
HostBusy (nAutofd) (cont.)
Reverse Idle Phase:
Set high in response to PtrClk (nAck) low pulse
to re-enter reverse data transfer phase. Is set
high with 1284 Active (nSelectIn) being set low,
the 1284 idle phase is being aborted and the
interface returns to Compatibility Mode.
Peripheral Logic High (+ 5V)
Set high to indicate that all other signals sourced by the printer are in
valid state. Set low to indicate the printer is off.
pppppp
n.a. (nInit)
Compatibility Mode:
Pulsed low in conjunction with 1284 Active low
to reset the interface and force to return to
Compatibility Mode idle phase.
Negotiation Phase:
Set HIGH.
Reverse Data Transfer
Phase:
Set HIGH.
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nDataAvail (NFault)
Compatibility Mode:
Set low to indicate that an internal printer error
has occurred.
Negotiation Phase:
Set high to acknowledge 1284 compatibility. In
Nibble or Byte Mode it is then set low to indicate
printer-to-host data is available following host
setting HostBusy (nAutoFd) high.
Reverse Data
Transfer Phase:
Nibble
Mode:
Set low to indicate that printer is
ready to send to host. Then used
to send data bits 0 then 4.
Byte Mode:
Used to indicate that data is
available.
Reverse Idle Phase:
Used to indicate that data is available.
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