7406 hex inverter buffer/driver (open collector) pinout
DIP-14. Serial bus line drivers (CLK, DATA, ATN acknowledge), stepper phase and LED drivers
Six open-collector inverters that pull the serial bus lines LOW. A partial failure is the classic "SEARCHING FOR" hang with the computer frozen: check the 7406 and the 74LS14 receivers next to the serial VIA (Ray Carlsen). A shorted output holds DATA or CLK LOW and hangs every device on the bus.
Open the interactive 7406 pinoutPins
| Pin | Name | Type | Signal |
|---|---|---|---|
| 1 | 1A | io | Inverter 1 input. |
| 2 | 1Y | io | Inverter 1 open-collector output. |
| 3 | 2A | io | Inverter 2 input. |
| 4 | 2Y | io | Inverter 2 open-collector output. |
| 5 | 3A | io | Inverter 3 input. |
| 6 | 3Y | io | Inverter 3 open-collector output. |
| 7 | GND | ground | Ground. |
| 8 | 4Y | io | Inverter 4 open-collector output. |
| 9 | 4A | io | Inverter 4 input. |
| 10 | 5Y | io | Inverter 5 open-collector output. |
| 11 | 5A | io | Inverter 5 input. |
| 12 | 6Y | io | Inverter 6 open-collector output. |
| 13 | 6A | io | Inverter 6 input. |
| 14 | VCC | power | +5 V supply. |
Fitted in
- Commodore 1541 disk drive UB1 and UD1 (short boards 251748); UA1 (1541C 250448); U7 (1541-II)
- Commodore 1571 disk drive U8, U16 (schematic 310420)
- Commodore 1581 disk drive U8, U12