The Negotiation Phase; Signals - InfoPrint 6500 User Manual

Byte Mode
The printer and host send data to each other along eight data lines (one bit
per line).
If bidirectional communication is supported by the printer and the host, the
host will take control of the data transfer.

The Negotiation Phase

The negotiation phase determines which operating mode will be used. At this
time, the host and the printer will sense what devices are attached, the
supported signals available, and which mode to use. The selected mode, in
turn, defines the pins on the 1284 connector.
There are 36 pins on the parallel interface. Each one sends a different signal.
Pin 1, for example, can send a Strobe signal or a HostC1k signal, depending
on the mode selected. See Table 8 for the different connector signals.

Signals

Table 8 lists each of the signals associated with the corresponding pins on the
1284 interface. Descriptions of the signals follow.
Pin Source of Data
1 Host
2 Host/Printer
3 Host/Printer
4 Host/Printer
5 Host/Printer
6 Host/Printer
7 Host/Printer
8 Host/Printer
9 Host/Printer
10 Printer
11 Printer
12 Printer
13 Printer
Table 8. 1284 Signals
Type of Mode
Compatible
nStrobe
Data 1 (LSB)
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
Data 8 (MSB)
nAck
Busy
PError AckDataReq
Select
The Negotiation Phase
Nibble Byte
HostClk Host/Clk
PtrClk PtrClk
PtrBusy PtrBusy
AckDataReq
Xflag Xflag
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