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Rebuilt: DELETED fabricated memory map, v3.4 ROM module table, 800KB format detail, MC6883 PAL/LM380 sound path and the easter egg; codename field held a model number; SCSI Manager in ROM clarified (no SCSI hardware); 4.5V alkaline PRAM cell and the 128K/512K voltage procedure cross-referenced; refs and reflist
 
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{{Infobox computer
{{Infobox computer
| name        = Macintosh 512Ke
| name        = Macintosh 512Ke
| image        = [[File:Macintosh128K.jpg|250px]]
| image        = [[File:Macintosh128K.jpg|250px]]
| manufacturer = Apple Computer, Inc.
| manufacturer = Apple Computer, Inc.
| type        = Personal Computer
| type        = Personal computer
| release_date = April 14, 1986
| release_date = April 1986
| discontinued = September 1, 1987
| discontinued = September 1987
| price        = US$1,999
| price        = US$1,999
| cpu          = Motorola 68000 @ 7.83 MHz
| cpu          = Motorola 68000 @ 7.83 MHz
| memory      = 512 KB RAM (built‑in)
| memory      = 512 KB, soldered, not user-expandable
| storage      = 800 KB 3.5″ floppy drive
| rom          = 128 KB
| display      = 9″ monochrome CRT (512×342)
| storage      = Internal double-sided 800 KB 3.5-inch floppy drive
| sound        = Monaural, 8‑bit
| display      = 9-inch monochrome CRT, 512 × 342 pixels
| dimensions  = 13.6″ H × 9.6″ W × 10.9″ D
| sound        = Four-voice, 8-bit D/A conversion, 22 kHz sampling
| weight      = 16.5 lbs (7.5 kg)
| ports        = DB-19 external floppy; DE-9 mouse; RJ-11 keyboard; 2 × serial
| os          = System 1.0 – System 6.0.8
| os          = System 3.2 – System 6.0.8
| predecessor  = [[Macintosh 512K]]
| predecessor  = [[Macintosh 512K]]
| successor    = [[Macintosh Plus]]
| successor    = [[Macintosh Plus]]
| codename    = M0001E
| model        = M0001E
| model        = 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.
The '''Macintosh 512Ke''' — "512K enhanced" — was introduced in April 1986 at US$1,999<ref name="ah">apple-history.com, ''Macintosh 512Ke'' (secondary source, used for the introduction price, market dates and the Macintosh ED education badge).</ref> as the cheap end of the range after the [[Macintosh Plus]] arrived. It is a [[Macintosh 512K]] fitted with the Plus's '''128 KB ROM''' and its '''double-sided 800 KB floppy drive''', which together bring HFS and the 800 KB disk format to the older case and logic board. The memory stays at 512 KB and stays soldered, and there is no SCSI port.


== Features ==
== 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 ==
* '''800 KB double-sided floppy drive''' — twice the capacity of the 400 KB single-sided drive in the 128K and 512K.
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.
* '''128 KB ROM''' — the same ROM used in the Macintosh Plus, which is what allows HFS volumes and the 800 KB format. The SCSI support in that ROM is of no use without the Plus's SCSI hardware, which this machine does not have.
* '''No expansion.''' No slots, no SIMM sockets, no SCSI connector. Third-party SCSI and memory boards existed but are logic board modifications.
* '''Macintosh ED''' — the education-channel badge applied to the same hardware.<ref name="ah" />


== Upgrade Paths ==
== System software ==
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.
Shipped with System 3.2 and supported through System 6.0.8, although 512 KB of memory makes the later systems impractical for real work.


== Maintenance ==
== Upgrades ==
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 ==
Apple's own upgrade path ran the other way: a [[Macintosh 512K]] could be converted to a 512Ke with the 800 KB drive and the 128 KB ROMs, and a 512Ke could be converted to a Macintosh Plus with a Plus logic board.<ref name="dms">Larry Pina, ''The Dead Mac Scrolls'', Peachpit Press, 1992, "Early Macs" chapter, which prices the 512Ke-to-Plus upgrade and documents the board-level faults quoted here. Hosted on this wiki: [[:File:The Dead Mac Scrolls 1992.pdf]].</ref>
<templatestyles src="Template:StyledTable/styles.css" />


=== System Architecture at a Glance ===
== Maintenance ==
{| 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) ===
The 512Ke shares its chassis, analogue board and servicing procedures with the [[Macintosh 128K]] and [[Macintosh 512K]]. See '''[[Macintosh 128K/512K General Maintenance]]'''.
{| 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 ===
The machine contains a CRT; read [[CRT Discharge Procedure]] before opening the case. Apple's published voltage procedure for this board family — voltage test cable 077-0135 on the external floppy port, '''11.90–12.75 V''' and '''4.85–5.15 V''' — is written up with its warnings on [[Macintosh Plus General Maintenance]].<ref name="ss128">Apple Computer, ''Macintosh 128K/512K Service Source'' — Specifications and Adjustments chapters. Hosted on this wiki: [[:File:Macintosh 128k.512k.pdf]].</ref>
* 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 ===
The PRAM cell is the same '''4.5 V user-replaceable alkaline''' type as the 128K and 512K, in a compartment on the rear of the case.<ref name="ss128" /> Alkaline leakage is neutralised with vinegar — unlike the lithium cells in the [[Macintosh SE]] and later compacts, which need bicarbonate.
* '''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 ===
== Known board-level faults ==
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 ===
A 512K or 512Ke that resets a directly connected ImageWriter II on the printer port, or that never shows up on an AppleTalk network while otherwise behaving normally, usually has a failed '''26LS30''' line driver at board location '''B6'''.<ref name="dms" />
* '''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 ===
== Related pages ==
Hold '''⌘ + Option + ⇧ + Clear''' at power-on for the hidden bass “startup” chime—retained from earlier ROMs.
* [[Macintosh 512K]]
* [[Macintosh 128K]]
* [[Macintosh Plus]]
* [[Macintosh 128K/512K General Maintenance]]
* [[Sad Mac Error Codes]] and the [[Sad Mac Decoder]]
* [[CRT Discharge Procedure]]


== References ==
<references />


[[Category:Apple Vintage Computers]]
[[Category:Apple Vintage Computers]]
{{Navbox-AppleVintage|state=collapsed}}
{{Navbox-AppleVintage|state=collapsed}}

Latest revision as of 18:16, 23 September 2026

Macintosh 512Ke
Specifications
ManufacturerApple Computer, Inc.
TypePersonal computer
ReleasedApril 1986
DiscontinuedSeptember 1987
Intro priceUS$1,999
CPUMotorola 68000 @ 7.83 MHz
Memory512 KB, soldered, not user-expandable
StorageInternal double-sided 800 KB 3.5-inch floppy drive
Display9-inch monochrome CRT, 512 × 342 pixels
SoundFour-voice, 8-bit D/A conversion, 22 kHz sampling
ROM128 KB
Ports / interfaceDB-19 external floppy; DE-9 mouse; RJ-11 keyboard; 2 × serial
OS / FirmwareSystem 3.2 – System 6.0.8
PredecessorMacintosh 512K
SuccessorMacintosh Plus
Model no.M0001E

The Macintosh 512Ke — "512K enhanced" — was introduced in April 1986 at US$1,999[1] as the cheap end of the range after the Macintosh Plus arrived. It is a Macintosh 512K fitted with the Plus's 128 KB ROM and its double-sided 800 KB floppy drive, which together bring HFS and the 800 KB disk format to the older case and logic board. The memory stays at 512 KB and stays soldered, and there is no SCSI port.

Features

[edit | edit source]
  • 800 KB double-sided floppy drive — twice the capacity of the 400 KB single-sided drive in the 128K and 512K.
  • 128 KB ROM — the same ROM used in the Macintosh Plus, which is what allows HFS volumes and the 800 KB format. The SCSI support in that ROM is of no use without the Plus's SCSI hardware, which this machine does not have.
  • No expansion. No slots, no SIMM sockets, no SCSI connector. Third-party SCSI and memory boards existed but are logic board modifications.
  • Macintosh ED — the education-channel badge applied to the same hardware.[1]

System software

[edit | edit source]

Shipped with System 3.2 and supported through System 6.0.8, although 512 KB of memory makes the later systems impractical for real work.

Upgrades

[edit | edit source]

Apple's own upgrade path ran the other way: a Macintosh 512K could be converted to a 512Ke with the 800 KB drive and the 128 KB ROMs, and a 512Ke could be converted to a Macintosh Plus with a Plus logic board.[2]

Maintenance

[edit | edit source]

The 512Ke shares its chassis, analogue board and servicing procedures with the Macintosh 128K and Macintosh 512K. See Macintosh 128K/512K General Maintenance.

The machine contains a CRT; read CRT Discharge Procedure before opening the case. Apple's published voltage procedure for this board family — voltage test cable 077-0135 on the external floppy port, 11.90–12.75 V and 4.85–5.15 V — is written up with its warnings on Macintosh Plus General Maintenance.[3]

The PRAM cell is the same 4.5 V user-replaceable alkaline type as the 128K and 512K, in a compartment on the rear of the case.[3] Alkaline leakage is neutralised with vinegar — unlike the lithium cells in the Macintosh SE and later compacts, which need bicarbonate.

Known board-level faults

[edit | edit source]

A 512K or 512Ke that resets a directly connected ImageWriter II on the printer port, or that never shows up on an AppleTalk network while otherwise behaving normally, usually has a failed 26LS30 line driver at board location B6.[2]

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 apple-history.com, Macintosh 512Ke (secondary source, used for the introduction price, market dates and the Macintosh ED education badge).
  2. ↑ 2.0 2.1 Larry Pina, The Dead Mac Scrolls, Peachpit Press, 1992, "Early Macs" chapter, which prices the 512Ke-to-Plus upgrade and documents the board-level faults quoted here. Hosted on this wiki: File:The Dead Mac Scrolls 1992.pdf.
  3. ↑ 3.0 3.1 Apple Computer, Macintosh 128K/512K Service Source — Specifications and Adjustments chapters. Hosted on this wiki: File:Macintosh 128k.512k.pdf.
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