5 PIN DIN 180° (DIN41524) FEMALE at the computer.
The IBM PC XT (Model 5160) keyboard connector is a 5-pin DIN 180° (DIN41524) socket located at the rear of the system unit. Introduced with the XT in 1983, it uses a one-directional synchronous serial protocol: the keyboard (driven by an Intel 8048 microcomputer) generates the clock and transmits make and break scan codes to the host; the host cannot send data back. Pin 3 carries an active-low keyboard reset signal, which was seldom connected by keyboards and was later repurposed as a spare pin on the IBM PC AT. All signal lines are open-collector, pulled to the +5 Vdc supply on pin 5.
| Pin | Name | Description | Technical |
|---|---|---|---|
| 1 | CLK | Clock | CLK/CTS, Open-collector |
| 2 | DATA | Data | RxD, Open-collector |
| 3 | /RESET | Reset | |
| 4 | GND | Ground | |
| 5 | VCC | +5 VDC |
Notes
The connector is physically identical to the 5-pin DIN used on the IBM PC AT; however, the protocols are incompatible. The XT protocol is one-directional (keyboard to host only), whereas the AT protocol is bidirectional. Pin 3 carries an active-low reset signal on the XT but is designated Spare on the AT. The keyboard cable is permanently attached and shielded, comprising four conductors: power, ground, and the two signal lines.
Signals
- CLK — Clock generated by the keyboard; synchronises the serial data stream. Open-collector, TTL level, pulled to +5 Vdc.
- DATA — Serial data line carrying make and break scan codes from the keyboard to the host. Open-collector, TTL level, pulled to +5 Vdc.
- /RESET — Active-low keyboard reset output from the host. Rarely connected by keyboards; not used in the standard XT keyboard.
- GND — Signal and power return; 0 V reference.
- VCC — +5 Vdc supply to the keyboard.