Specifications

2-24 Hardware
Confidential
7. When a temporary abnormality occurs in the power supply voltage.
8. When an error has occurred.
Reverse mode (data transmission from printer to host)
The STATUS data transmission from the printer to the host proceeds in the Nibble or Byte mode.
❏
Description
This mode allows data transmission from the asynchronous printer under the control of the
host.
Data transmissions in the Nibble Mode are made via the existing control lines in units of
four bits (a nibble). In the Byte Mode, data transmissions proceed by making the eight-bit
data lines bidirectional.
Both modes fail to proceed concurrently in the Compatibility Mode, causing half duplex
transmission.
Interface pin assignments for each mode
Pin Source Compatibility mode Nibble mode Byte mode
1 Host nStrobe HostClk HostClk
2 Host/Ptr Data0 (LSB) Data0 (LSB) Data0 (LSB)
3 Host/Ptr Data1 Data1 Data1
4 Host/Ptr Data2 Data2 Data2
5 Host/Ptr Data3 Data3 Data3
6 Host/Ptr Data4 Data4 Data4
7 Host/Ptr Data5 Data5 Data5
8 Host/Ptr Data6 Data6 Data6
9 Host/Ptr Data7 (MSB) Data7 (MSB) Data7 (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 Hostr nAutoFd HostBusy HostBusy
15 NC ND ND
16 GND GND GND
17 FG FG FG
18 Printer Logic-H Logic-H Logic-H
19 GND GND GND
20 GND GND GND
21 GND GND GND
22 GND GND GND
23 GND GND GND
24 GND GND GND