Apple Floppy Disk Drive
| Apple Floppy Disk Drive | |
|---|---|
 |
|
| Macintosh 800K External Drive (Model M0131) | |
| Manufacturer | Apple Computer, Inc. (Sony mechanism) |
| Type | Floppy disk drive |
| Discontinued | 1989 |
| Price | US$429 |
| Interface | DE-19 floppy port |
| Compatible | Macintosh Plus and later, Apple IIGS |
| Dimensions | ~200 mm × 180 mm × 35 mm |
| Weight | ~700 g |
| Predecessor | Macintosh External Disk Drive (M0130) |
| Successor | Apple SuperDrive |
| Model | M0131 |
The Macintosh 800K External Drive (model M0131) was Apple's double-sided 800 KB external floppy drive, introduced in January 1986 alongside the Macintosh Plus. It doubled the storage capacity of the original 400K drive while maintaining backward compatibility with single-sided disks. The slimmer beige case was later replaced by the Platinum gray Apple 3.5 Drive in 1986.
Background
The 800K drive used Sony's double-sided drive mechanism, already shipping in the Apple UniDisk 3.5 for Apple II since September 1985. Apple delayed the Macintosh version to coincide with the introduction of HFS (Hierarchical File System), which required the Macintosh Plus's 128K ROM.
Design
Physical Construction
The M0131 features a slimmer profile than the original M0130:
- Beige case matching Macintosh Plus
- Single DE-19 connector
- Auto-eject mechanism
- No daisy-chain port
Sony Mechanism
The internal drive mechanism features:
- Double-sided read/write heads
- GCR (Group Coded Recording) format
- Variable speed (5 zones)
- Faster access than 400K predecessor
- Quieter operation
Format Support
| Format | Capacity | Sides | Notes |
|---|---|---|---|
| 800K | 800 KB | Double-sided | Native format, HFS |
| 400K | 400 KB | Single-sided | Backward compatible, MFS |
The drive uses Apple's GCR variable-speed format:
- Inner tracks: 8 sectors, slower rotation
- Outer tracks: 12 sectors, faster rotation
- 80 tracks per side
- Higher capacity than PC's 720K MFM format
Compatibility
Native Support
Systems with 128K ROM:
- Macintosh Plus
- Macintosh SE
- Macintosh II series
Software Support Required
Systems with 64K ROM (via HD20 INIT):
- Macintosh 512Ke
- Original Macintosh 512K (with software)
Not Compatible
- Macintosh 128K (cannot load HFS)
Cross-Platform
The later Apple 3.5 Drive (A9M0106) replaced the M0131 and added Apple II compatibility. The M0131 is Macintosh-only.
Specifications
| Parameter | Value |
|---|---|
| Model number | M0131 |
| Part number | 825-1174-A |
| Capacity | 800 KB (double-sided) / 400 KB (single-sided) |
| Media | 3.5-inch DD floppy |
| Encoding | GCR variable speed |
| Tracks | 80 per side |
| Sectors | 8-12 per track (zoned) |
| Interface | DE-19 floppy port |
| Case color | Beige (early) / Platinum (later) |
| Mechanism | Sony auto-inject |
Speed Control
Unlike the 400K drive, the 800K drive controls its own rotational speed:
- Internal speed control circuitry
- No external speed signal required
- Universal mechanisms need speed signal isolation
Some "universal" mechanisms (also used in Apple II) require special cables when used on Macintosh to isolate speed control signals.
Maintenance
Head Cleaning
Use a 3.5-inch head cleaning disk periodically, especially if read errors increase.
Eject Mechanism
The auto-eject motor is a common failure point:
- Symptoms: Disk won't eject, motor buzzing
- Emergency eject: Insert paperclip into small hole
- Repair: Motor replacement
Common Issues
| Problem | Cause | Solution |
|---|---|---|
| Won't read | Dirty heads | Clean with cleaning disk |
| Won't eject | Eject motor failure | Paperclip or repair |
| Read errors | Worn heads | Replace mechanism |
| Not recognized | 64K ROM Mac | Install HD20 software |
| Speed issues | Universal mechanism | Use isolating cable |
Transition to Apple 3.5 Drive
In September 1986, Apple introduced the Apple 3.5 Drive (A9M0106):
- Platinum gray case (Snow White design)
- Cross-platform (Mac and Apple II)
- Daisy-chain connector
- Manual eject button
The M0131 was discontinued as the 3.5 Drive provided identical functionality with broader compatibility.
Collecting
Identification
- Model M0131 on label
- Beige case (Platinum for late production)
- DE-19 connector
- Slimmer than M0130 (400K)
Condition Assessment
- Mint: Original box, fully functional
- Excellent: Reads/writes reliably, clean
- Good: Functional, minor cosmetic wear
- Fair: Functions but occasional errors
- Poor: Non-functional or damaged
Testing
- Test with 800K formatted disk (read/write)
- Test with 400K formatted disk (backward compatibility)
- Verify eject mechanism works
See Also
References
- Wikipedia — Macintosh External Disk Drive
- Apple Technical Documentation