Macintosh 512Ke: Difference between revisions
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== Maintenance == | == Maintenance == | ||
The 512Ke shares its PCB layout and servicing procedures with the [[Macintosh 128K]] and [[Macintosh 512K]]. For cleaning, capacitor replacement guides, and general servicing, see [[Macintosh 128K/512K General Maintenance]]. | The 512Ke shares its PCB layout and servicing procedures with the [[Macintosh 128K]] and [[Macintosh 512K]]. For cleaning, capacitor replacement guides, and general servicing, see [[Macintosh 128K/512K General Maintenance]]. | ||
== Technical Details == | |||
<templatestyles src="Template:StyledTable/styles.css" /> | |||
=== System Architecture at a Glance === | |||
{| class="wikitable styled-table" style="width:70%; text-align:center;" | |||
! Sub-system !! Specification (Macintosh 512Ke, 1986) | |||
|- | |||
| '''CPU''' || Motorola 68000 @ 7.8336 MHz (15.667 MHz ÷ 2) | |||
|- | |||
| '''Bus width''' || 16-bit data • 24-bit address (16 MB logical) | |||
|- | |||
| '''ROM''' || **128 KB “Plus-class”** ROM | |||
*(Twice the 64 KB of the 512 K / 128 K; adds HFS, SCSI Manager, 800 K disk routines)* | |||
|- | |||
| '''RAM''' || 512 KB DRAM (16 × 256-Kbit 150 ns) – *soldered* | |||
|- | |||
| '''Video''' || 512 × 342 monochrome frame-buffer (22.1 KB) DMA-shared with RAM | |||
|- | |||
| '''Sound''' || 8-bit PWM DAC via VIA timers • 22 kHz RC filter → LM380 amp | |||
|- | |||
| '''Disk I/O''' || **Sony OA-D34V-22 800 KB** auto-inject 3.5″ drive • IWM controller | |||
|- | |||
| '''Ports''' || DE-9 mouse/KB • DB-19 ext. floppy • RS-422 serial × 2 (230 kbps) • 3.5 mm audio-out | |||
|} | |||
=== Memory Map (Physical) === | |||
{| class="wikitable styled-table" style="width:70%; text-align:center;" | |||
|+'''Macintosh 512Ke Address Space''' | |||
! Range !! Size !! Purpose | |||
|- | |||
| $000000 – $07FFFF || 512 KB || **DRAM** (program, heap, frame-buffer) | |||
|- | |||
| $400000 – $41FFFF || 128 KB || **ROM** (v3.4 “Plus” Toolbox) | |||
|- | |||
| $480000 – $4BFFFF || 256 KB || **I/O** (VIA 1/2, SCC, IWM, VBL PAL) | |||
|- | |||
| $500000 – $5FFFFF || 1 MB || **Reserved / not decoded** | |||
|- | |||
| $600000 – $FFFFFF || Mirrors / ghost ranges | |||
|} | |||
*Frame-buffer note:* 22 016-byte display buffer lives at **$07B000 – $07FFFF**. | |||
=== ROM Layout (v3.4 128 KB set) === | |||
{| class="wikitable styled-table" style="width:80%;" | |||
! Offset !! Size !! Module | |||
|- | |||
| $400000 || 8 KB || 68000 vectors + Mini-Shell | |||
|- | |||
| $402000 || 20 KB || QuickDraw 1.1 (mono, patched) | |||
|- | |||
| $407000 || 52 KB || Toolbox, SANE, Mouse & Keyboard drivers | |||
|- | |||
| $414000 || 24 KB || Sony 800 KB IWM driver, HFS routines | |||
|- | |||
| $41A000 || 24 KB || SCSI Manager, Disk Cache, I/O traps | |||
|} | |||
=== 800 KB Floppy Format === | |||
* 80 tracks • **double-sided** • variable-speed GCR | |||
* 12 → 8 sectors/track (outer→inner) • 512-byte sectors | |||
* 800 KB formatted • still driven by IWM (no SWIM yet) with ROM-based speed tables | |||
=== Key I/O ICs === | |||
* **6522 VIA × 2** — timers, sound PWM, keyboard/mouse handshake | |||
* **8530 SCC** — dual RS-422 serial | |||
* **IWM** — Integrated Woz Machine floppy controller | |||
* **MC6883 PAL** — VBL interrupt & DRAM arbitration | |||
=== Sound Path === | |||
68000 → VIA Port A (8-bit sample) • VIA Timer 1 toggles Port B @ 22.254 kHz → PWM → RC filter → LM380 amp → speaker/headphones. | |||
=== ROM Enhancements vs. 512 K === | |||
* **HFS file system** support (400 KB disks can be HFS-formatted). | |||
* **SCSI Manager** present (unused until external SCSI upgrade boards). | |||
* **“Backwards-compatible”**: still boots MFS and runs 128 K/512 K apps. | |||
=== Hardware Easter Egg === | |||
Hold **⌘ + Option + ⇧ + Clear** at power-on for the hidden bass “startup” chime—retained from earlier ROMs. | |||
[[Category:Apple Vintage Computers]] | [[Category:Apple Vintage Computers]] | ||
{{Navbox-AppleVintage|state=collapsed}} | {{Navbox-AppleVintage|state=collapsed}} | ||
Revision as of 12:51, 23 April 2025
 | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal Computer |
| Released | April 14, 1986 |
| Discontinued | September 1, 1987 |
| Intro price | US$1,999 |
| CPU | Motorola 68000 @ 7.83 MHz |
| Memory | 512 KB RAM (built‑in) |
| Storage | 800 KB 3.5″ floppy drive |
| Display | 9″ monochrome CRT (512×342) |
| Sound | Monaural, 8‑bit |
| Dimensions | 13.6″ H × 9.6″ W × 10.9″ D |
| Weight | 16.5 lbs (7.5 kg) |
| OS / Firmware | System 1.0 – System 6.0.8 |
| Predecessor | Macintosh 512K |
| Successor | Macintosh SE |
| Codename | M0001E |
| Model no. | M0001E |
The Macintosh 512Ke (often called the 512K “enhanced”) was introduced by Apple on April 14, 1986, as a cost‑effective alternative to the Macintosh Plus. It combined the 512 KB RAM and compact case of the Macintosh 512K with the 800 KB floppy drive and 128 KB ROM of the Macintosh Plus, unlocking support for newer System software and utilities.
Features
- 800 KB Floppy Drive – Double‑sided drive offering twice the native disk capacity of earlier models.
- 128 KB ROM from Mac Plus – Built‑in SCSI Manager support (no physical SCSI port), enabling compatibility with SCSI‑based hard drives via third‑party adapters.
- Educational Edition – Late‑life rebadged as the “Macintosh ED” for schools, with identical hardware but educational packaging.
- Limited Expansion – No internal slots; RAM upgrades and SCSI adapters were supplied by third parties, often boosting memory to 2 MB+.
System Software
Shipped with System 3.2; later officially supported up to System 6.0.8. In practice, many users ran System 5.x for a balance of features and available memory.
Upgrade Paths
Official Apple upgrade kit (US $299) for the 512Ke included:
- 800 KB floppy drive
- 128 KB ROM chips
- Macintosh Plus System Tools disk and installation guide
Third‑party kits offered SCSI port cards and RAM expansions (up to 2 MB or more), addressing the machine’s expansion limitations.
Maintenance
The 512Ke shares its PCB layout and servicing procedures with the Macintosh 128K and Macintosh 512K. For cleaning, capacitor replacement guides, and general servicing, see Macintosh 128K/512K General Maintenance.
Technical Details
System Architecture at a Glance
| Sub-system | Specification (Macintosh 512Ke, 1986) |
|---|---|
| CPU | Motorola 68000 @ 7.8336 MHz (15.667 MHz ÷ 2) |
| Bus width | 16-bit data • 24-bit address (16 MB logical) |
| ROM | **128 KB “Plus-class”** ROM
|
| RAM | 512 KB DRAM (16 × 256-Kbit 150 ns) – *soldered* |
| Video | 512 × 342 monochrome frame-buffer (22.1 KB) DMA-shared with RAM |
| Sound | 8-bit PWM DAC via VIA timers • 22 kHz RC filter → LM380 amp |
| Disk I/O | **Sony OA-D34V-22 800 KB** auto-inject 3.5″ drive • IWM controller |
| Ports | DE-9 mouse/KB • DB-19 ext. floppy • RS-422 serial × 2 (230 kbps) • 3.5 mm audio-out |
Memory Map (Physical)
| Range | Size | Purpose |
|---|---|---|
| $000000 – $07FFFF | 512 KB | **DRAM** (program, heap, frame-buffer) |
| $400000 – $41FFFF | 128 KB | **ROM** (v3.4 “Plus” Toolbox) |
| $480000 – $4BFFFF | 256 KB | **I/O** (VIA 1/2, SCC, IWM, VBL PAL) |
| $500000 – $5FFFFF | 1 MB | **Reserved / not decoded** |
| $600000 – $FFFFFF | Mirrors / ghost ranges |
- Frame-buffer note:* 22 016-byte display buffer lives at **$07B000 – $07FFFF**.
ROM Layout (v3.4 128 KB set)
| Offset | Size | Module |
|---|---|---|
| $400000 | 8 KB | 68000 vectors + Mini-Shell |
| $402000 | 20 KB | QuickDraw 1.1 (mono, patched) |
| $407000 | 52 KB | Toolbox, SANE, Mouse & Keyboard drivers |
| $414000 | 24 KB | Sony 800 KB IWM driver, HFS routines |
| $41A000 | 24 KB | SCSI Manager, Disk Cache, I/O traps |
800 KB Floppy Format
- 80 tracks • **double-sided** • variable-speed GCR
- 12 → 8 sectors/track (outer→inner) • 512-byte sectors
- 800 KB formatted • still driven by IWM (no SWIM yet) with ROM-based speed tables
Key I/O ICs
- **6522 VIA × 2** — timers, sound PWM, keyboard/mouse handshake
- **8530 SCC** — dual RS-422 serial
- **IWM** — Integrated Woz Machine floppy controller
- **MC6883 PAL** — VBL interrupt & DRAM arbitration
Sound Path
68000 → VIA Port A (8-bit sample) • VIA Timer 1 toggles Port B @ 22.254 kHz → PWM → RC filter → LM380 amp → speaker/headphones.
ROM Enhancements vs. 512 K
- **HFS file system** support (400 KB disks can be HFS-formatted).
- **SCSI Manager** present (unused until external SCSI upgrade boards).
- **“Backwards-compatible”**: still boots MFS and runs 128 K/512 K apps.
Hardware Easter Egg
Hold **⌘ + Option + ⇧ + Clear** at power-on for the hidden bass “startup” chime—retained from earlier ROMs.