HP 2500C Series - Manual (Page 19)

Product Information 1-11
Specifications
The Centronics Parallel Cable has only 8 data lines, 5 status lines, 4 ground lines and
ground connections between the host PC and the peripheral. Each of the signal lines has a
corresponding bit position in a memory address (register) in the host where data is read or
written. Sending data to the printer follows the sequence below:
§ Host places data in Data Out register
§ Host sends pulse on Strobe line
§ Printer sends pulse on Busy in response to pulse on Strobe
§ Printer reads data on Data Out lines
§ Printer sends pulse on ACK (Acknowledge) line after data is read
This method of data transfer is also known as the Compatibility mode and the transfer
rate of data is slow. The printer while operating in compatibility mode is capable of
indicating limited printer error feedback to the host computer. Such feedback includes:
§ Paper jam
§ Out of paper
§ Printer on or off line
§ Time out