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Rebuilt against Apple Classic/Classic II/Performa 200 Service Source: DELETED fabricated memory map, ROM SIMM module table, SWIM-II/53C80 detail, MacBench benchmark table, Seattle/LittleFish codenames and MacsBug easter egg, and the 512KB 32-bit-clean/HFS+ ROM claim; CPU 8MHz -> 7.8336MHz, ONE ADB port (not two), Apple dimensions and 100W; predecessor SE/30 -> SE; added the real Command-Option-X-O ROM disk; fixed red link to a nonexistent Troubleshooting page; release_date parameter fixed; re...
 
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| caption      = Macintosh Classic
| caption      = Macintosh Classic
| manufacturer = Apple Computer, Inc.
| manufacturer = Apple Computer, Inc.
| type        = Personal Computer
| type        = Personal computer
| release date = October 15, 1990
| release_date = 15 October 1990
| discontinued = September 14, 1992
| discontinued = 14 September 1992
| price        = US$999 – $1,499
| price        = US$999 (floppy only) – US$1,499 (40 MB hard disk, 2 MB RAM)
| cpu          = Motorola 68000 @ 8 MHz
| cpu          = Motorola 68000 @ 7.8336 MHz
| memory      = 1 MB RAM (expandable to 4 MB)
| memory      = 1 MB soldered, expandable to 4 MB with Apple's memory expansion board
| storage      = 1.44 MB 3.5" floppy drive, optional 40 MB SCSI hard drive
| rom          = 512 KB
| display      = 9" monochrome CRT (512×342 pixels)
| storage      = Internal 1.4 MB floppy drive; optional internal 40 MB SCSI hard disk
| sound        = Monaural 8-bit, 22 kHz
| display      = 9-inch monochrome CRT, 512 × 342 pixels
| dimensions  = 13.2" 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        = 1 × ADB (mini-DIN-4); DB-19 external floppy; DB-25 SCSI; 2 × RS-422 serial (mini-DIN-8); headphone
| power        = 100–120 V AC, 47–63 Hz, 100 W maximum
| dimensions  = 13.2 in H × 9.7 in W × 11.2 in D (33.6 × 24.6 × 28.5 cm)
| weight      = 16–17.1 lb (7.3–7.8 kg) without a hard disk
| os          = System 6.0.7 – System 7.5.5
| os          = System 6.0.7 – System 7.5.5
| predecessor  = [[Macintosh SE/30]]
| predecessor  = [[Macintosh SE]]
| successor    = [[Macintosh Classic II]]
| successor    = [[Macintosh Classic II]]
| codename    = Elsie, Skywriter
| codename    = XO, Civic
| model        = M0420
| model        = M0420
}}
}}
The '''Macintosh Classic''' was introduced by Apple on October 15, 1990, as a low-cost alternative in the Macintosh lineup and a spiritual successor to the original Macintosh 128K and SE/30. It retained the same 9-inch monochrome display and compact form factor, but included a 1.44 MB SuperDrive and optional internal SCSI hard drive. It was the first Macintosh to sell for under $1,000, making it a popular choice for schools and home users.
The '''Macintosh Classic''', introduced on 15 October 1990, was the first Macintosh to sell for under US$1,000. It is a cost-reduced compact: the same 68000 at 7.8336 MHz as the [[Macintosh SE]], a 1.4 MB floppy drive, an optional 40 MB hard disk, and — unlike the SE — '''no expansion slot and only one ADB port'''.<ref name="sscl">Apple Computer, ''Macintosh Classic/Classic II/Performa 200 Service Source'' — Specifications, Troubleshooting, Upgrades, Adjustments and Additional Procedures chapters. Hosted on this wiki: [[:File:Classic ii.performa 200.pdf]].</ref><ref name="lem">Low End Mac, ''Mac Classic'' tech specs (secondary source, used for dates, prices, codenames and the ROM disk).</ref>


== General Maintenance ==
== Specifications ==
For cleaning, battery maintenance, board inspection, and power supply tuning, refer to the [[Macintosh Classic General Maintenance]] page.


== PCB Schematics & Service Manual ==
Apple's own specification pages for this family.<ref name="sscl" />


The Macintosh Classic includes two main PCBs: a unified logic board and an analog board. Below are the schematics and Apple’s official service manual.
=== Apple Service Manual ===
<pdf width="800" height="500">File:Macintosh_Classic_-_Classic_II.pdf</pdf>
All Apple Service Manuals can be found on the [[:Category:Apple Service Source|Apple Service Source]] page.
=== Logic Board & Analog Board Schematics ===
{| class="wikitable" style="width:50%; text-align:center;"
|+'''Macintosh Classic PCB Schematics'''
|-
! style="background-color:#f2f2f2; width:30%;"| Logic Board
! style="background-color:#f2f2f2; width:30%;"| Analog Board
|-
| [[File:MacintoshClassicLogicBoard.jpg|thumb|center|250px|Macintosh Classic Logic Board]][[File:MacintoshClassic LogicBoard Schematic.pdf|center|thumb|Macintosh Classic Logic Board Schematic]]
| [[File:MacintoshClassic AnalogBoard.jpg|center|thumb|250x250px|Macintosh Classic Analog Board]][[File:Classic Analog Board Schematic.pdf|center|thumb|Macintosh Classic Analog Board Schematic]]
|}
== Capacitor Replacement Guide ==
Full details on logic and analog board recapping can be found at the [[Macintosh Classic Capacitor Replacement Guide]].
== Retrobrite ==
To restore the beige color of the Classic’s case, refer to the safe plastic whitening procedures outlined on the [[Retrobrite]] page.
== Troubleshooting ==
For diagnosis and solutions to common issues including no startup, checkerboard patterns, floppy drive problems, and failed PRAM batteries, see the [[Macintosh Classic Troubleshooting]] guide.
== Technical Details ==
<templatestyles src="Template:StyledTable/styles.css" />
<templatestyles src="Template:StyledTable/styles.css" />
 
{| class="wikitable styled-table" style="width:85%;"
=== System Architecture at a Glance ===
! Item !! Specification
{| class="wikitable styled-table" style="width:90%; text-align:center;"
! Sub-system !! Specification (Macintosh Classic, Oct 1990)
|-
| '''CPU''' || Motorola 68000 @ 7.8336 MHz (15.667 MHz ÷ 2)
|-
| '''FPU''' || — (none; not socketed)
|-
|-
| '''Bus width''' || 16-bit data • 24-bit address (16 MB logical)
| CPU || Motorola 68000, 7.8336 MHz, 32-bit internal data bus, 256-byte instruction and data caches
|-
|-
| '''ROM''' || '''512 KB “SE/30-class”''' ROM SIMM (v7.0) — 32-bit clean, HFS+, Color QD
| RAM || 1 MB, expandable to 4 MB (120 ns or faster SIMMs)
|-
|-
| '''RAM''' || 1 MB soldered • '''Expansion card adds 1 MB + 2 × 30-pin SIMM slots → 4 MB max'''
| ROM || 512 KB
|-
|-
| '''Video''' || 512 × 342 monochrome — 22.1 KB DMA steal from main DRAM
| PRAM || 256 bytes
|-
|-
| '''Sound''' || 8-bit PWM DAC via VIA timers • 22 kHz → RC filter → LM380 amp
| Expansion connector || 44-pin connector for the optional memory expansion board, which itself carries two SIMM connectors
|-
|-
| '''Disks''' || Internal Sony SWIM-II 800 KB (FDHD option 1.44 MB) • 40 MB SCSI HDD (BTO)
| Floppy || Internal 1.4 MB; optional external 800 KB or 1.4 MB
|-
|-
| '''Ports''' || ADB • DB-19 ext. floppy • DB-25 SCSI-1 • Geo/SCC serial × 2 • 3.5 mm audio-out
| Hard disk || Optional internal 40 MB; external SCSI supported
|-
|-
| '''Expansion''' || '''No PDS'''; memory–I/O expansion via proprietary 96-pin mezzanine card
| ADB || '''One''' port, mini-DIN-4
|}
 
=== Memory Map (Physical) ===
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+ '''Macintosh Classic Address Space'''
! Range !! Size !! Purpose
|-
|-
| $0000 00 – $0FFF FF || 1 MB || '''On-board DRAM'''
| Serial || Two RS-422 ports, mini-DIN-8
|-
|-
| $1000 00 – $4FFF FF || 4 MB || '''Expansion DRAM''' (if present → 4 MB ceiling)
| Sound || Four-voice, 8-bit D/A conversion, 22 kHz sampling. The Classic does not provide true two-channel output, although a stereo jack may be used
|-
|-
| $4000 00 – $47FF FF || 512 KB || '''ROM SIMM''' (v7.0)
| Video || 9-inch diagonal, 512 × 342 bit-mapped monochrome
|-
|-
| $5000 00 – $50FF FF || 64 KB || '''I/O bank A''' – VIA 1/2, SCC, SWIM-II, ADB, VBL PAL
| Line voltage || 100–120 V AC
|-
|-
| $5800 00 – $58FF FF || 64 KB || '''SCSI NCR 53C80 regs + glue'''
| Frequency || 47–63 Hz, single phase
|-
|-
| $5C00 00 – $5FFF FF || 256 KB || '''Expansion card decode''' (memory & option EEPROM)
| Maximum power || 100 W
|-
|-
| $9000 00 – $9000 FF || 256 B || Frame-buffer shift register (mirrored)
| Dimensions || 13.2 × 9.7 × 11.2 in (33.6 × 24.6 × 28.5 cm)
|-
|-
| $C000 00 – $FF FF FF || Mirrors / reserved
| Weight || 16–17.1 lb (7.3–7.8 kg), excluding an internal hard disk
|}
|}


=== ROM SIMM Layout (512 KB, v7.0) ===
== Memory ==
{| class="wikitable styled-table" style="width:90%;"
 
! Offset !! Size !! Module
There are no SIMM sockets on the Classic's logic board. The 1 MB on board is soldered, and expansion happens on Apple's optional memory expansion board: 1 MB soldered plus a pair of 30-pin SIMM sockets and a configuration jumper, giving 2 MB, 2.5 MB or 4 MB.<ref name="sscl" />
|-
 
| $4000 00 || 16 KB || 68000 vectors & Mini-Shell
Two rules from Apple that cause most of the trouble:
|-
* the jumper must match what is fitted — "SIMMs" or "No SIMMs";
| $4004 00 || 64 KB || QuickDraw 1.3 (monochrome & color, 32-bit)
* on a 4 MB machine the modules must be '''eight-chip''' SIMMs. Apple states that 1 MB SIMMs with fewer than eight chips will not work in the Macintosh Classic.<ref name="sscl" />
|-
 
| $4014 00 || 192 KB || Toolbox, Window/Menu mgrs., SANE FP
Full procedure: [[Macintosh Classic Memory Upgrade Guide]].
|-
 
| $4044 00 || 80 KB || SWIM-II floppy, ASC sound, ADB Egret
== The ROM disk ==
|-
 
| $405E 00 || 96 KB || SCSI Manager 4.3, Disk Cache, HFS/HFS+
The Classic is the only Macintosh that can boot from its own ROM. Holding '''Command-Option-X-O''' at startup mounts a 357 KB read-only volume named "Boot Disk" containing System 6.0.3 and Finder 6.1.x — a reference to the machine's XO codename. It is genuinely useful for diagnosis: a Classic that will not boot from a disk but does boot from ROM has a working logic board, ROM, RAM and video.<ref name="lem" /><ref name="eeggs">The Macintosh Easter Egg List and Low End Mac both document the Command-Option-X-O ROM disk, its contents and its 357 KB size (secondary sources).</ref>
|}


=== SWIM-II Floppy Controller ===
== Service manual and schematics ==
* 800 KB GCR variable-speed (standard) 
* FDHD build-to-order: 1.44 MB MFM + 800 KB GCR (autodetect) 
* Supports intelligent-step motor timing; faster reads on outer tracks.


=== SCSI & Mass-Storage ===
=== Apple service manual ===
* '''NCR 53C80''' 8-bit controller — 5 MB s⁻¹ sync (≈1.1 MB s⁻¹ async real-world) 
<pdf width="800" height="500">File:Macintosh_Classic_-_Classic_II.pdf</pdf>
* “Pseudo-DMA” using block-moves by CPU; internal drive on 50-pin ribbon.


=== Key I/O ICs ===
All the Apple service manuals are on the [[:Category:Apple Service Source|Apple Service Source]] page.
* '''6522 VIA × 2''' — system timers, sound PWM, keyboard‐handshake 
* '''8530 SCC''' — dual RS-422 serial (up to 230 kbps) 
* '''SWIM-II''' — floppy & GCR/MFM selector 
* '''NCR 53C80''' — SCSI 
* '''Egret (68HC05)''' — ADB, soft-power, PRAM battery 


=== Sound Path ===
=== Logic board and analogue board ===
68000 → VIA Port A (8-bit sample) • VIA Timer 1 @ 22.254 kHz toggles Port B → PWM → RC filter → LM380 → speaker / rear jack.


=== RAM Expansion Notes ===
{| class="wikitable" style="width:50%; text-align:center;"
{| class="wikitable styled-table" style="width:75%; text-align:center;"
|+'''Macintosh Classic PCB images'''
! Total RAM !! Expansion Card SIMMs !! Jumper
|-
| 2 MB || none (card only) || “No SIMMs” (JP top) 
|-
|-
| 2.5 MB || 2 × 256 KB || “With SIMMs” (JP bottom) 
! style="background-color:#f2f2f2; width:30%;"| Logic board
! style="background-color:#f2f2f2; width:30%;"| Analogue board
|-
|-
| 4 MB || 2 × 1 MB || “With SIMMs” (JP bottom) 
| [[File:MacintoshClassicLogicBoard.jpg|thumb|center|250px|Macintosh Classic logic board]][[File:MacintoshClassic LogicBoard Schematic.pdf|center|thumb|Macintosh Classic logic board schematic]]
| [[File:MacintoshClassic AnalogBoard.jpg|center|thumb|250x250px|Macintosh Classic analogue board]][[File:Classic Analog Board Schematic.pdf|center|thumb|Macintosh Classic analogue board schematic]]
|}
|}


* SIMMs: 30-pin, 120 ns, 8-chip, non-parity only. 
== Maintenance, capacitors and troubleshooting ==
* Mixed sizes not supported; SIMMs must match pair.


=== Performance Benchmarks ===
* '''[[Macintosh Classic / Classic II General Maintenance]]''' — cleaning, the 3.6 V lithium cell and its 3.0 V replacement threshold, and what Apple does and does not publish about the rails.
{| class="wikitable styled-table" style="width:70%; text-align:center;"
* '''[[Macintosh Classic Capacitor Replacement Guide]]''' — values and positions.
! Test (MacBench 1.0) !! Score !! vs Mac Plus
* '''[[Macintosh Classic / Classic II Troubleshooting]]''' — symptom-led diagnosis.
|-
* '''[[CRT Discharge Procedure]]''' — read before opening the case.
| CPU integer || 115 || × 1.43 
* '''[[Retrobrite]]''' — for the yellowed case.
|-
 
| Disk (40 MB SCSI) || 230 || × 1.92 
'''Apple publishes no rail tolerance and no power-supply adjustment for this machine.''' Its Adjustments chapter is video and yoke work only — light meter setup, cutoff, brightness and contrast, centring, size, focus.<ref name="sscl" /> Note also that ''The Dead Mac Scrolls'', the standard component-level reference for the earlier compacts, explicitly does not cover the Classic.<ref name="dms">Larry Pina, ''The Dead Mac Scrolls'', Peachpit Press, 1992, introduction. Hosted on this wiki: [[:File:The Dead Mac Scrolls 1992.pdf]].</ref>
|-
 
| Graphics (QD) || 100 || × 1.00 
Sad Mac codes are decoded on [[Sad Mac Error Codes]] and with the [[Sad Mac Decoder]].
|-
 
| Overall || 123 || × 1.53 
== Related pages ==
|}
* [[Macintosh SE]] and [[Macintosh SE/30]]
* [[Macintosh Classic II]]
* [[Macintosh Color Classic]]


=== Hardware Trivia ===
== References ==
* Last '''68000-based''' Macintosh; ROM identical to SE/30 but 32-bit addressing disabled. 
<references />
* “*Seattle*” logic board codename; early EVT boards silk-screened “LittleFish”. 
* Easter egg: type '''`G 40E053`''' in MacsBug to reveal the original compact-Mac developers list.


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

Latest revision as of 18:18, 23 September 2026

Macintosh Classic
Macintosh Classic
Specifications
ManufacturerApple Computer, Inc.
TypePersonal computer
Released15 October 1990
Discontinued14 September 1992
Intro priceUS$999 (floppy only) – US$1,499 (40 MB hard disk, 2 MB RAM)
CPUMotorola 68000 @ 7.8336 MHz
Memory1 MB soldered, expandable to 4 MB with Apple's memory expansion board
StorageInternal 1.4 MB floppy drive; optional internal 40 MB SCSI hard disk
Display9-inch monochrome CRT, 512 × 342 pixels
SoundFour-voice, 8-bit D/A conversion, 22 kHz sampling
ROM512 KB
Ports / interface1 × ADB (mini-DIN-4); DB-19 external floppy; DB-25 SCSI; 2 × RS-422 serial (mini-DIN-8); headphone
Power100–120 V AC, 47–63 Hz, 100 W maximum
Dimensions13.2 in H × 9.7 in W × 11.2 in D (33.6 × 24.6 × 28.5 cm)
Weight16–17.1 lb (7.3–7.8 kg) without a hard disk
OS / FirmwareSystem 6.0.7 – System 7.5.5
PredecessorMacintosh SE
SuccessorMacintosh Classic II
CodenameXO, Civic
Model no.M0420

The Macintosh Classic, introduced on 15 October 1990, was the first Macintosh to sell for under US$1,000. It is a cost-reduced compact: the same 68000 at 7.8336 MHz as the Macintosh SE, a 1.4 MB floppy drive, an optional 40 MB hard disk, and — unlike the SE — no expansion slot and only one ADB port.[1][2]

Specifications

[edit | edit source]

Apple's own specification pages for this family.[1]

Item Specification
CPU Motorola 68000, 7.8336 MHz, 32-bit internal data bus, 256-byte instruction and data caches
RAM 1 MB, expandable to 4 MB (120 ns or faster SIMMs)
ROM 512 KB
PRAM 256 bytes
Expansion connector 44-pin connector for the optional memory expansion board, which itself carries two SIMM connectors
Floppy Internal 1.4 MB; optional external 800 KB or 1.4 MB
Hard disk Optional internal 40 MB; external SCSI supported
ADB One port, mini-DIN-4
Serial Two RS-422 ports, mini-DIN-8
Sound Four-voice, 8-bit D/A conversion, 22 kHz sampling. The Classic does not provide true two-channel output, although a stereo jack may be used
Video 9-inch diagonal, 512 × 342 bit-mapped monochrome
Line voltage 100–120 V AC
Frequency 47–63 Hz, single phase
Maximum power 100 W
Dimensions 13.2 × 9.7 × 11.2 in (33.6 × 24.6 × 28.5 cm)
Weight 16–17.1 lb (7.3–7.8 kg), excluding an internal hard disk

Memory

[edit | edit source]

There are no SIMM sockets on the Classic's logic board. The 1 MB on board is soldered, and expansion happens on Apple's optional memory expansion board: 1 MB soldered plus a pair of 30-pin SIMM sockets and a configuration jumper, giving 2 MB, 2.5 MB or 4 MB.[1]

Two rules from Apple that cause most of the trouble:

  • the jumper must match what is fitted — "SIMMs" or "No SIMMs";
  • on a 4 MB machine the modules must be eight-chip SIMMs. Apple states that 1 MB SIMMs with fewer than eight chips will not work in the Macintosh Classic.[1]

Full procedure: Macintosh Classic Memory Upgrade Guide.

The ROM disk

[edit | edit source]

The Classic is the only Macintosh that can boot from its own ROM. Holding Command-Option-X-O at startup mounts a 357 KB read-only volume named "Boot Disk" containing System 6.0.3 and Finder 6.1.x — a reference to the machine's XO codename. It is genuinely useful for diagnosis: a Classic that will not boot from a disk but does boot from ROM has a working logic board, ROM, RAM and video.[2][3]

Service manual and schematics

[edit | edit source]

Apple service manual

[edit | edit source]

All the Apple service manuals are on the Apple Service Source page.

Logic board and analogue board

[edit | edit source]
Macintosh Classic PCB images
Logic board Analogue board
Macintosh Classic logic board
File:MacintoshClassic LogicBoard Schematic.pdf
Macintosh Classic analogue board
File:Classic Analog Board Schematic.pdf

Maintenance, capacitors and troubleshooting

[edit | edit source]

Apple publishes no rail tolerance and no power-supply adjustment for this machine. Its Adjustments chapter is video and yoke work only — light meter setup, cutoff, brightness and contrast, centring, size, focus.[1] Note also that The Dead Mac Scrolls, the standard component-level reference for the earlier compacts, explicitly does not cover the Classic.[4]

Sad Mac codes are decoded on Sad Mac Error Codes and with the Sad Mac Decoder.

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 Apple Computer, Macintosh Classic/Classic II/Performa 200 Service Source — Specifications, Troubleshooting, Upgrades, Adjustments and Additional Procedures chapters. Hosted on this wiki: File:Classic ii.performa 200.pdf.
  2. ↑ 2.0 2.1 Low End Mac, Mac Classic tech specs (secondary source, used for dates, prices, codenames and the ROM disk).
  3. ↑ The Macintosh Easter Egg List and Low End Mac both document the Command-Option-X-O ROM disk, its contents and its 357 KB size (secondary sources).
  4. ↑ Larry Pina, The Dead Mac Scrolls, Peachpit Press, 1992, introduction. Hosted on this wiki: File:The Dead Mac Scrolls 1992.pdf.


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