ProgrammerManual PTX‐S828
AppendixB‐Interfaces 365 260071‐001A
The pins 1 to 14 of the printer are connected to the pins with the same number of the parallel port of the
host.
The pins 19 to 30 of the printer are connected to the pins 18 to 25 of the parallel port of the host.
The pins 31, 32 and 36 of the printer are connected respectively to the pins 16, 15 and 17 of the parallel port
of the host.
1284 Mode signal names are shown with their Compatibility mode (Centronics) names in parenthesis ( ) for
the bidirectional link.
Signal Name Pin N° for Pin N° for
Signal Wire Return Wire Source
HostClk (nStrobe) 1 19 HOST
AD1 (Data 1) 2 20 HOST in Compatibility mode and negotiation
phase.
AD2 (Data 2) 3 21
AD3 (Data 3) 4 22 NOT USED in Nibble mode.
AD4 (Data 4) 5 23
AD5 (Data 5) 6 24 BIDIRECTIONAL in Byte mode.
AD6 (Data 6) 7 25
AD7 (Data 7) 8 26
AD8 (Data 8) 9 27
PrtClk (nAck) 10 28 PRINTER
PrtBusy (Busy) 11 29 PRINTER
AckDataReq (PError) 13 28 PRINTER
Xflag (Select) 14 28 PRINTER
HostBusy (nAutofd) 15 30 HOST
Peripheral Logic High 18 PRINTER
(+5 V)
n.a. (nInit) 31 30 HOST
nDataAvail (NFault) 32 29 PRINTER
1284 Active (NSelectIn) 36 30
Common Logic Ground 16 and Return Wires
Chassis Ground 17
Parallel Interface Signals Behaviour
HostClk /nWrite (nStrobe)
Compatibility Mode: Set Active low to transfer data into printer input latch. Data is valid while nStrobe is
low.
Negotiation Phase: Set active low to transfer extendibility request value into printer input latch. Data is
valid on the falling edge of HostClk.
Reverse Data Transfer Set high during Nibble Mode transfer to avoid latching data into printer. Pulsed
Phase: low during Byte Mode transfers to acknowledge transfer of data from the printer.
The printer shall ensure that this pulse does not transfer a new data into the printer
input latch.
AD1 ... AD8 (Data 1 ... Data 8)
Compatibility Mode: Forward channel data.
Negotiation Phase: Extendibility request value.
Reverse Data Transfer Nibble Mode: NOT USED.
Phase: Byte Mode: Reverse channel data.
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