Rev. 3.02
- 26 -
SRP-270
3-5-3(b) Reverse Mode Specification (Nibble / Byte mode)
Data transmission from the printer to the host computer.
The STATUS data transmission from the printer to the host computer is accomplished in the Nibble or Byte
mode. This mode allows data transmission from the asynchronous printer under the control of the host
computer. Data transmission in the Nibble mode are made via the existing control lines in units of for bits
(Nibble). In the Byte mode, data transmission in accomplished by making the 8-bit data lines bidirectional.
Neither mode can operate at the same time as the compatibility mode, so switching is always required.
3-5-3(c) Signal Specification (Compatibility/Nibble/Byte mode)
Pin No. Source Compatibility Mode Nibble Mode Byte Mode
1 Host nStrobe HostClk HostClk
2 Host / Printer Data 0 (LSB) - Data 0 (LSB)
3 Host / Printer Data 1 - Data 1
4 Host / Printer Data 2 - Data 2
5 Host / Printer Data 3 - Data 3
6 Host / Printer Data 4 - Data 4
7 Host / Printer Data 5 - Data 5
8 Host / Printer Data 6 - Data 6
9 Host / Printer Data 7 (MSB) - Data 7 (MSB)
10 Printer nAck PtrClk PtrClk
11 Printer Busy PtrBusy/Data3,7 PtrBusy
12 Printer Perror AckDataReq /Data2,6 AckDataReq
13 Printer Select Xflag/Data1,5 Xflag
14 Host nAutoFeed HostBusy HostBusy
15 NC ND ND
16 GND GND GND
17 FG FG FG
18 Printer Logic-H Logic-H Logic-H
19~30 GND GND GND
31 Host nlnit nInit nlnit
32 Printer nFault nDataAvail /Data0,4 nDataAvail
33 GND ND ND
34 Printer DK_Status ND ND
35 Printer +5V ND ND
36 Host nSelectln 1284-Active 1284-Active
Table 3-19 IEEE1284 Pin Description
3-5-3(c) IEEE1284 I/F Cable
Host
Side
Printer Centronics
Side 36P
Figure 3-9 IEEE1284 Cable
