Compuprint 10200 Programmer Manual - Manual (Page 217)

Interfaces
213
AD1 … AD8 (Data 1 … Data 8)
Compatibility Mode: Forward channel data.
Negotiation Phase: Extendibility request value.
Nibble Mode: NOT USED. Reverse Data Transfer
Phase:
Byte Mode: Reverse channel data.
PrtClk (nAck)
Compatibility Mode: Pulsed low by the printer to acknowledge the transfer of a data from the
host.
Negotiation Phase: Set low to acknowledge 1284 support, then set high to indicate that the
Xflag (Select) and data available flags may be read.
Reverse Data Transfer
Phase: Used in both Nibble and Byte Modes to qualify data being sent to the host.