UniDisk 5.25
Beige half-height 5.25 in drive with a pass-through port: two per controller card, one on a IIc.
Open the UniDisk 5.25 in Retro Bench- Also
- UniDisk 5.25 A9M0104: half-height, captive DB-19 cable plus a DB-19 daisy-chain socket; on the UniDisk (5.25 Drive) controller card in a II, II Plus or IIe, or on the Apple IIc external drive port (drive 2, driven by the IIc IWM)
- Year
- 1984
- CPU
- none (dumb drive)
- ROM
- On the controller card: P5 341-0027 and P6 341-0028 (Disk II circuit); on a IIc the IWM and the IIc ROM do the work
- OS
- DOS 3.3 / ProDOS
Chips
| Chip | Where | Role |
|---|---|---|
| IWM 344-0041 Integrated Woz Machine | In the host Apple IIc (main board), not in the drive | Floppy disk controller |
| P6 state-sequencer PROM 341-0028 (256 × 8, 6309 type) | PROM P6 on the 5.25 controller card (II/IIe hosts only) | Logic state sequencer program (the "state machine") |
| P5 boot PROM 341-0027 (256 × 8, 6309 type) | PROM P5 on the 5.25 controller card (II/IIe hosts only) | Controller boot code at $Cn00-$CnFF |
| 74LS323 8-bit universal shift/storage register | 74LS323 on the 5.25 controller card (II/IIe hosts only) | Controller data register (shifts disk bits in and out) |
| 74LS259 8-bit addressable latch (9334) | 74LS259 on the 5.25 controller card (II/IIe hosts only) | Controller soft switches $C080-$C08F,X: phases, motor, drive select, Q6, Q7 |
| 74LS174 hex D flip-flop | 74LS174 on the 5.25 controller card (II/IIe hosts only) | Sequencer state latch and read-pulse synchronizer |
Ports and connectors
- DB-19 drive port (controller card plate or IIc rear), DB-19 socket the UniDisk cable plugs into (the drive's captive cable ends in the mating plug)
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | 4.75-5.25 V | uni-db19 pin 6 |
| +12 V | 10.8-13.2 V (+12 V ±10 %, IIc TRM Table 11-4) | uni-db19 pins 7, 8 |
| -12 V | -12 V | uni-db19 pin 5 |
Symptoms
- Third or fourth UniDisk not seen
- Will not boot from the UniDisk on a IIc: check IWM
- Drive dead on a IIc, built-in drive fine: check IWM
- Spins but will not boot on a II/IIe: check P6, 74LS174, 74LS323