Disk II Cable Pinout
This table shows the pinout of the original 1979 Disk II controller and newer 1983 Uni/Duo Disk I/O controller (655-0101).
The circuitry of these two controllers are identical. The Disk II header pin numbering is per the Disk II controller card silkscreen and the circuit schematic given in the DOS 3.3 manual. The Uni/Duo Disk D-19 pinout is taken from the Apple //c Reference Manual, Volume 1.
| Disk II Header Pin | DuoDisk/Disk IIc/UniDisk/Apple Disk D-19 Pin | DuoDisk/UniDisk/Apple Disk Controller Card Cable Color | Signal Name | Description |
|---|---|---|---|---|
| 1,3,5,7 | 1,2,3,4 | Brown,Orange,Green,Violet | GND | Ground reference and supply |
| 2 | 11 | Red | SEEKPH0 | Phase 0 stepper motor signal |
| 4 | 12 | Yellow | SEEKPH1 | Phase 1 stepper motor signal |
| 6 | 13 | Blue | SEEKPH2 | Phase 2 stepper motor signal |
| 8 | 14 | Grey | SEEKPH3 | Phase 3 stepper motor signal |
| 9 | 5 | White | -12V | -12 volt supply |
| 10 | 15 | Black | WRREQ* | Write request signal |
| 11,12 | 6,16 | Brown,Red | +5V | +5 volt supply |
| 13,15,17,19 | 7,8 | Orange,Green | +12V | +12 volt supply |
| 14 | 17 | Yellow | DR2* (ENABLE*) | Drive 2 select/Drive enable signal |
| 16 | 18 | Blue | RDDATA | Read data signal |
| 18 | 19 | Grey | WRDATA | Write data signal |
| 20 | 10 | White | WRPROT | Write protect signal |
| x | 9 | Violet | EXINT* | External interrupt |
NOTES:
- Active low signals are suffixed with a "*"
- Since most signals are shared with both drive 1 and drive 2, the logic in each drive uses the ENABLE* signal to activate appropriately.
- Pin 14 for Disk II drive 1 and drive 2 have separate enable signals (14a and 14b)
- Pin 17 for Uni/Duo Disk is chained to first drive (drive 1) and second drive (drive 2) is enabled via other logic in the first drive.
- The EXTINT* signal is not present on the Disk II controller card. In the Apple //c computer, it is routed to the DSR* signal of the internal 6551 ACIA (UART) chip.
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