| PC-Pin | SPP-Func | ECP-Func | PC-Dir | PC-Bit | MSP-Port | MSP-Dir | Forward | Reverse | |
|---|---|---|---|---|---|---|---|---|---|
| 1 | -Strobe | HostCLK | Out | Ctrl.0 | P1.0 | In | 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. | unused | |
| 2 | D0 | D0 | I/O | Data.0 | P5.0 | I/O | Data Bus. Bi-directional | ||
| 3 | D1 | D1 | I/O | Data.1 | P5.1 | I/O | |||
| 4 | D2 | D2 | I/O | Data.2 | P5.2 | I/O | |||
| 5 | D3 | D3 | I/O | Data.3 | P5.3 | I/O | |||
| 6 | D4 | D4 | I/O | Data.4 | P5.4 | I/O | |||
| 7 | D5 | D5 | I/O | Data.5 | P5.5 | I/O | |||
| 8 | D6 | D6 | I/O | Data.6 | P5.6 | I/O | |||
| 9 | D7 | D7 | I/O | Data.7 | P5.7 | I/O | |||
| 10 | -ACK | PeriphCLK | In | Stat.6 | P4.0 | Out | 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 | PeriphAck | In | Stat.7 | P4.1 | Out | In forward direction, functions as PeriphAck. | When in reverse direction a HIGH indicates Data, while a LOW indicates a Command Cycle. | |
| 12 | PaperOut | AckReverse | In | Stat.5 | P4.2 | Out | When Low, Device acknowledges Reverse Request. | ||
| 13 | Select | X-Flag | In | Stat.4 | P4.3 | Out | Extensibility Flag | ||
| 14 | AutoFeed | HostAck | Out | Ctrl.1 | P1.2 | In | When in forward direction a HIGH indicates Data, while a LOW indicates a Command Cycle. | In reverse direction, functions as HostAck. | |
| 15 | ErrorIn | PeriphRequest | In | Stat.3 | P4.4 | Out | A LOW set by the device indicates reverse data is available. | ||
| 16 | INIT | ReverseRequest | Out | Ctrl.2 | P1.3 | In | A LOW indicates data is in reverse direction | ||
| 17 | SelectPrinter | 1284 Active | Out | Ctrl.3 | P1.4 | In | A HIGH indicates Host is in 1284 Transfer Mode | ||
| 18-25 | GND | - | - | - | - | - | - | - | |