| Pin | Name | Description | 
| 1 | /STROBE | A low on this line indicates, that there is valid data at the host. When this pin is de-asserted, the +ve clock edge should be used to shift the data into the device. | 
| 2 | Data 0 | Address, Data or RLE Data Bit 0 | 
| 3 | Data 1 | Address, Data or RLE Data Bit 1 | 
| 4 | Data 2 | Address, Data or RLE Data Bit 2 | 
| 5 | Data 3 | Address, Data or RLE Data Bit 3 | 
| 6 | Data 4 | Address, Data or RLE Data Bit 4 | 
| 7 | Data 5 | Address, Data or RLE Data Bit 5 | 
| 8 | Data 6 | Address, Data or RLE Data Bit 6 | 
| 9 | Data 7 | Address, Data or RLE Data Bit 7 | 
| 10 | Ack | A low on this line indicates, that there is valid data at the Device. When this pin is de-asserted, the +ve clock edge should be used to shift the data into the Host. | 
| 11 | Busy | When in reverse direction a HIGH indicates Data, while a LOW indicates a Command Cycle. | 
| 12 | Paper Out / End | When Low, Device acknowledges Reverse Request. | 
| 13 | Select | Extensibility Flag | 
| 14 | Auto Linefeed | When in forward direction a HIGH indicates Data, while a LOW indicates a Command Cycle. | 
| 15 | Error / Fault | A LOW set by the device indicates reverse data is available | 
| 16 | Initialize | A LOW indicates data is in reverse direction | 
| 17 | Select Printer | A HIGH indicates Host is in 1284 Transfer Mode. Taken low to terminate. | 
| 18 | GND | Signal Ground | 
| 19 | GND | Signal Ground | 
| 20 | GND | Signal Ground | 
| 21 | GND | Signal Ground | 
| 22 | GND | Signal Ground | 
| 23 | GND | Signal Ground | 
| 24 | GND | Signal Ground | 
| 25 | GND | Signal Ground |