Editing Apple Floppy Disk Drive

{{Infobox computer peripheral
| image = [[File:Apple Floppy Disk Drive.jpg]]
| caption = Macintosh 800K External Drive (Model M0131)
| manufacturer = Apple Computer, Inc. (Sony mechanism)
| type = Floppy disk drive
| released = January 1986
| 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 = [[Apple 400K Drive|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 ==

{| class="wikitable"
|-
! 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 ==

{| class="wikitable"
|-
! 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 ===

{| class="wikitable"
|-
! 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 ==
* [[Apple 400K Drive]]
* [[Apple 3.5 Drive]]
* [[Apple SuperDrive]]
* [[Apple UniDisk 3.5]]

== References ==
* Wikipedia — Macintosh External Disk Drive
* Apple Technical Documentation

[[Category:Apple Vintage Accessories]]

{{Navbox-AppleVintageAccessories}}