| Type | Keyboard connector | ||
|---|---|---|---|
| Production history | |||
| Designer | IBM | ||
| Designed | 1984 | ||
| Superseded by | PS/2 connector Universal Serial Bus | ||
| General specifications | |||
| Pins | 5 | ||
| Connector | Male at the keyboard side, DIN connector | ||
| Data | |||
| Data signal | Serial data at 10 to 16 kHz with 1 stop bit, 1 start bit, 1 parity bit (odd) | ||
| Pin out | |||
| Female (at the computer side, viewed from front) | |||
| Pin 1 | CLK | Clock signal | |
| Pin 2 | DATA | Data | |
| Pin 3 | N/C | Not connected. Reset on older keyboards | |
| Pin 4 | GND | Ground | |
| Pin 5 | VCC | +5V DC | |
The AT keyboard was a keyboard with 84 keys introduced with the IBM PC/AT computer. It succeeded the 83-key PC/XT keyboard and therefore did not have many of the features seen on modern keyboards such as arrow keys and dual ctrl and alt keys. It was later replaced with the 101-key Enhanced keyboard. Nonetheless, "AT keyboard" remains a popular name for any keyboard that uses the five-pin DIN connector. This connector is often considered a Legacy port. Many Enhanced keyboards used this, though it was eventually superseded by the PS/2 connector and many modern computers use Universal Serial Bus (USB) connectors instead.
Compared to the 83-key XT keyboard, the AT keyboard uses a different communication protocol and a different set of scancodes. Despite having the same connector, the two are not interchangeable.