nAutoFd/HostBusy/HostAck
Compatibility mode: Not used.
negotiation phase: In order to request 1284 mode, this si gnal is set low and
IEEE 1284active (nSelectln) is set high. Afterwards, thi s signal is set high
when PtrClk (nAck) is set low.
reverse data transfer phase: In nibble mode, setting this signal low
indicates to the printer that the host is ready to receive data. When this
signal is subsequently set high, it indicates that the host received the dat a.
reverse idle phase: This signal is set high in response to a PtrClk (nAc k)
low pulse in order to return to the reverse data phase. If this sign al is set
high at the same time that IEEE 1284active (nSelec t ln) is set low t he IEEE
1284 idle phase is aborted and the interface returns to compati bility mode.
ECP mode: Used for reverse direction flow control. Al so u sed f or
handshaking via PeriphClk (nAck).
NC
Not used.
PeripheralLogicHigh
Parallel B: NC.
Parallel C: Pull up to +5V with 3.9 KΩ.
nlnit/nReverseRequest
Compatibility mode: When a low signal is detected, the prin te r is deemed
to be BUSY until the low signal is released.
negotiation phase: Always high.
reverse data transfer phase: Always high.
ECP mode: Low w hen switching to reverse dir ection. The pe ripheral
device has permission to drive the data signals only when this signal is
low and 1284active is high.
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Technical Specifications A-9