82091AA Datasheet, PDF (23/204 Pages) Intel Corporation – ADVANCED INTEGRATED PERIPHERAL (AIP)

82091AA
2 6 3 BYTE MODE SIGNAL DESCRIPTION
The Byte protocol assigns the following signal operation to the parallel port pins The name in bold at the
beginning of the signal description column is the Byte protocol signal name The terms assert and negate are
used in accordance with the 82091AA signal name as described at the beginning of Section 2 0 For example
STROBE (HostClk) asserted refers to STROBE (HostClk) at a low level
82091AA
Signal Name
STROBE
BUSY
ACK
SELECT
PERROR
FAULT
INIT
AUTOFD
PD 7 0
SELECTIN
Type
O
I
I
I
I
I
O
O
O
IO
Byte Protocol Signal Name and Description
HOST CLOCK (HostClk) This signal is strobed low by the host to acknowledge
receipt of data Note that the peripheral must not interpret this as a latch strobe
for forward channel data
PRINTER BUSY (PtrBusy) The peripheral device asserts BUSY (PtrBusy) to
provide forward channel peripheral busy status The status of this signal line is
reported in the PSTAT Register
PRINTER CLOCK (PtrClk) The peripheral device asserts ACK (PtrClk) to
indicate to the host that data is available The signal is subsequently asserted to
qualify data being sent to the host The status of this signal line is reported in the
PSTAT Register If interrupts are enabled via the PCON Register the assertion
of this signal causes a host interrupt to be generated
XFLAG SELECT (XFLAG) is asserted by the peripheral device to indicate that
the device is on line The status of this signal line is reported in the PSTAT
Register
ACKNOWLEDGE DATA REQUEST (AckDataReq) This signal is initially high
The peripheral device drives this signal low to acknowledge HostBusy assertion
The status of this signal line is reported in the PSTAT Register
DATA AVAILABILITY (DataAvail) The peripheral device asserts FAULT
(DataAvail) to indicate data availability The status of this signal line is reported in
the PSTAT Register
INITIALIZE The host controls this signal via the PCON Register and INIT
should be held in the negated state
HOST BUSY (HostBusy) The host negates AUTOFD (HostBusy) in response
to ACK being asserted The signal is subsequently driven low to enable the
peripheral to transfer data to the host AUTOFD is then driven high to
acknowledge receipt of nibble data This signal is controlled via the PCON
Register
DATA This 8-bit data bus is used for bi-directional data transfer
SELECT INPUT This signal is controlled by the PCON Register
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