Parallel Port (DB-25 / LPT Interface)
Standard 25-pin D-Sub parallel interface for printers and peripherals. Pin 1 is Strobe, pins 2–9 are bidirectional 8-bit data lines (SPP/EPP/ECP modes), pins 10–13 and 15 are status inputs, pins 14/16/17 are control outputs, and pins 18–25 are signal ground.
Aliase:LPT Port, Parallel Port, DB-25 Printer Port, Centronics Interface, IEEE 1284, D-Sub 25
DB-25 Female Receptacle (PC/Host Side, Front View)
25 Pins
Pinout Table25
| Pin | Signal / Name | Type | Alternative Functions |
|---|---|---|---|
| 1 | /STROBE | Digital | Strobe — Active-Low pulse latches data into device (output from host) |
| 2 | D0 | Digital | Data Bit 0 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 3 | D1 | Digital | Data Bit 1 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 4 | D2 | Digital | Data Bit 2 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 5 | D3 | Digital | Data Bit 3 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 6 | D4 | Digital | Data Bit 4 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 7 | D5 | Digital | Data Bit 5 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 8 | D6 | Digital | Data Bit 6 — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 9 | D7 | Digital | Data Bit 7 (MSB) — Bidirectional data line (SPP: output from host; EPP/ECP: bidirectional) |
| 10 | /ACK | Digital | Acknowledge — Active-Low pulse signals byte received and device ready for next (input to host) |
| 11 | BUSY | Digital | Busy — High = device not ready to accept data; Low = ready (input to host) |
| 12 | PE | Digital | Paper End — High = out of paper or media (input to host) |
| 13 | SELECT | Digital | Select — High = device is online and selected (input to host) |
| 14 | /AUTOFEED | Digital | Auto Feed — Active-Low instructs device to auto-linefeed after each carriage return (output from host) |
| 15 | /ERROR | Digital | Error — Active-Low signals device error condition (input to host) |
| 16 | /INITIALIZE | Digital | Initialize — Active-Low resets the device (output from host) |
| 17 | /SELECT_IN | Digital | Select In — Active-Low selects the device for communication (output from host) |
| 18 | GND | Ground | Signal Ground (return for /STROBE) |
| 19 | GND | Ground | Signal Ground (return for D0) |
| 20 | GND | Ground | Signal Ground (return for D1) |
| 21 | GND | Ground | Signal Ground (return for D2) |
| 22 | GND | Ground | Signal Ground (return for D3) |
| 23 | GND | Ground | Signal Ground (return for D4–D5) |
| 24 | GND | Ground | Signal Ground (return for D6–D7) |
| 25 | GND | Ground | Signal Ground (return for control lines) |