| Data port (read-write) Base address + 0 |
Status port (read-only) Base address + 1 |
Control port (read-write) Base address + 2 |
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Note :
All data port signals are true logic : 1 -> +5 volts, 0 -> 0 volts.
-STROBE, -AUTOFEED, -SELECT IN, -ERROR and -ACK are inverted : 1 -> 0 volts, 0 -> 5 volts,
every other control and status signals are true logic.
Only C3-C0 and S7-S3 are connected to paraller port connector.
| Register | Connector DB25 | Signal | PC IN/OUT |
|---|---|---|---|
| D0 | 2 | Data, bit 0 | Out |
| D1 | 3 | Data, bit 1 | Out |
| D2 | 4 | Data, bit 2 | Out |
| D3 | 5 | Data, bit 3 | Out |
| D4 | 6 | Data, bit 4 | Out |
| D5 | 7 | Data, bit 5 | Out |
| D6 | 8 | Data, bit 6 | Out |
| D7 | 9 | Data, bit 7 | Out |
| C0 | 1 | -STROBE | Out |
| C1 | 14 | -AUTOFEED | Out |
| C2 | 16 | INIT | Out |
| C3 | 17 | -SELECT IN | Out |
| S3 | 15 | -ERROR | In |
| S4 | 13 | SELECT | In |
| S5 | 12 | PE | In |
| S6 | 10 | -ACK | In |
| S7 | 11 | BUSY | In |
| GND | 25 | GND |