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iDP3221 User’s Manual
23
CITIZEN
6. PARALLEL INTERFACE
6.1 Bi-directional Parallel Interface (IEEE 1284)
6.1.1 Compatibility Mode (Host →
→→
→ Printer Communication Using the Centronics Interface)
(1) Outline
The familiar Centronics interface is used in the Compatibility mode.
(2) Specifications
Data transfer : 8-bit parallel
Synchronization : External nStrobe signal
Handshaking : nAck and Busy signals
Signal level : All signals TTL compatible
Connector : 57LE-40360 or equivalent (IEEE, 1284 Type B)
6.1.2 Reverse Mode (Printer →
→→
→ Host Communication)
Status data may be transferred from the printer to the host in either the Nibble or Byte mode.
Outline:
It is assumed that data is transferred from an asynchronous printer controlled from the host.
The existing control lines are used in transferring data in the Nibble mode (transferred in 4-bit units
(nibbles)). Data is transferred in both directions on 8 data lines in the Byte mode (8-bit units (bytes)).
As simultaneous execution with the Compatibility mode is not possible, half-duplex communication is
employed. See Appendix 2 for details.