| STROBE: | Active low pulse used to transfer data into the printer. | Pulse with must be between 0.5 and 500 microseconds for most printers. |
| Dn: | Data lines, high is a one. | |
| ACK: | Active low pulse indicates that data has been received and the printer is ready to accept more. | |
| BUSY: | A high signal indicates that the printer cannot receive data. | |
| PE: | A high signal indicates that the printer is out of paper (Paper End) | |
| SELECT OUT: | A high signal indicates that the printer is on-line | |
| AUTO FEED: | A low signal indicates to the printer that a line feed is required after each Carriage return. | This signal is used as a ground line by some manufacturers. |
| OSCXT: | A 100-200 KHz signal used by true Centronics printers only. | |
| +5V: | +5Vdc | Not provided by all manufacturers |
| PRIME: | A low signal resets the printer to its power-up state and the printer buffer is cleared | |
| FAULT: | A low signal indicates that the printer is in an off-line or error state | |
| LINE COUNT: | Used by true Centronics printers only. | Most of the time not used |
| SELECT IN: | A high signal indicates to the printer that a DC1/ DC3 code is valid. | This signal is used by a few manufacturers |