The Interface Boards

Handshaking

timing

 

 

 

 

 

 

 

 

Print buffer

area

Printer

status

Printer output

 

 

 

Vacant area = 256 bytes

Cannot receive input data

S e n d s X - O F F c o d e o r

 

 

 

 

sets DTR flag to "1"

 

 

 

 

Vacant area = 528 bytes

Can receive

input data

Sends X-ON code or

 

 

 

 

resets DTR flag to "0"

 

 

 

 

 

Error handling

When a parity error is detected, your printer prints an asterisk (*). All other errors are ignored.

A-10 Appendix