Citizen Systems CBM1000 Appendix 4. Parallel Interface, Bidirectional Parallel Interface IEEE1284

APPENDIX 4. PARALLEL INTERFACE

1 Bidirectional Parallel Interface (IEEE1284)

1.1Compatibility Mode (Host → Printer communication: Centronics compliant)

(1)General description

This printer provides Compatibility Mode, which specifies the Centronics interface conventionally used for a wide variety of applications.

(2)Specifications

Data transfer method:	8 bit parallel
Synchronizing method:	Controlled by nStrobe signal externally supplied
Handshaking:	Handled by nAck and Busy signals
Signal level:	All signals are TTL compatible

1.2Reverse Mode (Printer → Host communication)

Data transfer from the printer to the host computer is conducted in Nibble or Byte Mode.

(1)Outline

The reverse mode has been devised to handle data transfer from an asynchronous printer controlled by a host computer.

In Nibble Mode, data is transferred, 4 bits (a nibble) at a time, using traditional control lines. In Byte Mode, data is transferred by making 8 bit data lines bidirectional. Note that either mode cannot work simultaneously with Compatibility Mode, thus resulting in half-duplex transmission.

2. Connector Pin Assignments

Host side

D-Sub 25 pin (Male)

Pin No.	Signal name
1	nStrobe
2—9	Data0—7
10	nAck
11	Busy
12	PError
13	Select
14	nAutoFd
16	nlnit
15	nFault
17	nSelectln
18–25	GND

Printer side IEEE1284-B (Receptacle)

Pin No.	Signal name
1	nStrobe
2—9	Data0—7
10	nAck
11	Busy
12	PError
13	Select
14	nAutoFd
31	nlnit
32	nFault
36	nSelectln
19—30	GND
15—18	N.C.
33—35	N.C.

APPENDIX

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