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The 8279 is a general-purpose programmable keyboard and display 1/O interface device designed for use with microprocessors. The keyboard portion can provide a scanned interface to a 64-contact key matrix. The keyboard portion will also interface to an array of sensors or a strobed interface keyboard, such as the hall effect and ferrite variety. Key depressions can be a 2-key lockout or N-key rollover. Keyboard entries are debounced and strobed in an 8 character FIFO. if more than 8 characters are entered, overrun status is set. Key entries set the interrupt output line to the CPU.
8279 Pinout
8279 Pin Configuration
| Pin No | Pin Name | Description |
|---|---|---|
| 1,2,5,6,7,38,39 | RL0-RL7 | Return Line |
| 12-19 | DB0-DB7 | DIRECTIONAL DATA BUS |
| 3 | CLK | CLOCK Pin |
| 9 | RESET | RESET Pin |
| 22 | CS | Chip Select |
| 10,11 | RD/WR | Read/Write Pin |
| 4 | IRAQ | Interrupt Request Pin |
| 20,40 | VCC/VSS | Supply Voltage/Collector Voltage |
| 22-35 | SL0-SL3 | Scan Lines |
| 36 | SHIFT | Shift Pin |
| 37 | CONTROL STB | CONTROL/STROBED INPUT MODE |
| 21 | AD | Buffer Address |
| 24-27 | A0-A3 | Output Address Pin |
| 28-31 | B0-B3 | B Address Pin |
8279 Key Features
- Simultaneous Keyboard Display Operations
- Scanned Keyboard Mode
- Scanned Sensor Mode
- Strobed Input Entry Mode
- 8-Character Keyboard FIFO
- Single 16-Character Display
- Right or Left Entry 16-8yte Display RAM
You can download this datasheet for 8279 Programmable Keyboard/Display Interface – Datasheet from the link given below:
