Macintosh Classic
 | |
| Macintosh Classic with ADB keyboard and mouse (Wikimedia Commons, CC BY-SA 3.0) | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal computer |
| Released | 15 October 1990 |
| Discontinued | 14 September 1992 |
| Intro price | US$999 (floppy only); US$1,499 (40 MB hard disk, 2 MB RAM) |
| CPU | Motorola 68000 @ 7.8336 MHz |
| Memory | 1 MB on the logic board; 4 MB maximum with Apple's memory expansion board |
| Storage | Internal 1.4 MB floppy drive; optional internal 40 MB SCSI hard disk |
| Display | 9-inch monochrome CRT, 512 × 342 pixels |
| Sound | Four-voice, 8-bit D/A conversion, 22 kHz sampling |
| ROM | 512 KB |
| Ports / interface | 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 (220 V power/sweep boards also exist) |
| Dimensions | 13.2 in H × 9.7 in W × 11.2 in D (33.6 × 24.6 × 28.5 cm) |
| Weight | 7.3–7.8 kg (16–17.1 lb) without a hard disk |
| OS / Firmware | System 6.0.7 – System 7.5.5 |
| Predecessor | Macintosh SE |
| Successor | Macintosh Classic II |
| Codename | XO, Civic |
| Model no. | M0420 |
The Macintosh Classic is a compact Macintosh introduced on 15 October 1990 as the first Macintosh to sell for under US$1,000: $999 with a floppy drive only and 1 MB of RAM, or $1,499 with a 40 MB hard disk and 2 MB. It was discontinued on 14 September 1992.[1] It has the 7.8336 MHz 68000 of the Macintosh SE, a 1.4 MB floppy drive and an optional 40 MB hard disk, with one ADB port and no expansion slot other than the connector for Apple's memory expansion board.[2] The front-panel brightness knob of earlier compacts is gone; brightness is set from the Brightness control panel.[1]
Specifications
[edit | edit source]| Item | Specification |
|---|---|
| CPU | Motorola 68000, 7.8336 MHz, 32-bit internal data bus |
| 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 carries two SIMM connectors |
| Floppy | Internal 1.4 MB; optional external 800 KB or 1.4 MB (DB-19) |
| Hard disk | Optional internal 40 MB; external SCSI (DB-25) |
| 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 headphone jack is fed from the mono output, and Apple notes that the Classic does not provide true two-channel output |
| 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 |
The specification pages give only the 100–120 V rating, but the exploded view lists 220 V versions of the power/sweep board as well as 110 V ones (see Service parts).[3]
Memory
[edit | edit source]The logic board carries 1 MB, soldered, and has no SIMM sockets. Apple's optional memory expansion board, for the Classic only, plugs into the 44-pin connector and carries another 1 MB soldered plus a pair of SIMM connectors and a jumper. Fitting two 256 KB or two 1 MB SIMMs (120 ns or faster) and moving the jumper takes the machine to 2.5 MB or 4 MB.[2][4]
Apple's symptom chart for a Sad Mac at start-up names the two usual mistakes: the jumper on the memory expansion board must be set to "SIMMs" or "No SIMMs" to match what is fitted, and a 4 MB Classic needs eight-chip SIMMs, because 1 MB SIMMs with fewer than eight chips will not work in the Macintosh Classic.[5] Low End Mac advises against buying a Classic without the memory expansion board unless another is available.[1] The full procedure is on Macintosh Classic Memory Upgrade Guide.
The ROM disk
[edit | edit source]Holding Command-Option-X-O at start-up boots the Classic from a 357 KB read-only volume in ROM named "Boot Disk", holding System 6.0.3 and Finder 6.1.x. Its only control panels are General, Brightness and Startup Disk, and nothing can be added to it. Low End Mac describes booting from ROM as a feature unique to the Classic.[1]
Service parts
[edit | edit source]| Part | Apple part number |
|---|---|
| Logic board (Classic, 1 MB) | 661-0596 |
| Power/sweep board, 110 V | 661-0597 (Rev. A), 661-0651 (Rev. B) |
| Power/sweep board, 220 V | 661-0599 (Rev. A), 661-0652 (Rev. B) |
| CRT and yoke assembly | 076-0546 |
| Floppy drive | 661-0474 |
| Hard drive, 40 MB | 661-0216 |
| Lithium battery | 742-0011 |
| Floppy drive cable | 590-0167 |
| Hard drive power cable | 590-0521 |
The 110 V and 220 V power/sweep boards are different parts; check which one you have before using a capacitor list.
Service manual and schematics
[edit | edit source]
Apple's Macintosh Classic/Classic II/Performa 200 Service Source (115 pages, embedded above) is described at Macintosh Classic/ Classic II/Performa 200 Service Source. Its Light Meter Setup covers three meter models (R77, L-248 and 246).[2]
The manual settles two points for this machine. The clock battery is lithium and is replaced below 3.0 V, measured on the 10 V DC range with the cover off, the CRT discharged and the logic board removed.[6] And there is no power-supply voltage adjustment: the Adjustments chapter covers light meter setup, video and yoke only, so the rail-tolerance figures published for the Macintosh 128K, 512K and Plus do not apply here.[7]
The cover comes off after removing four Torx case screws and separating the cover with a case spreader; the two black screws go in the bottom and the two silver screws in the top when it is refitted. Apple warns that the edges of the metal chassis may be sharp.[8]
Logic board and power/sweep board
[edit | edit source]| Logic board | Power/sweep board |
|---|---|
 |
 |
Apple's manual calls the Classic's combined power supply and deflection board the power/sweep board.[9] BOMARC's schematics of the two 110 V power/sweep boards, 820-0395-A and 820-0525-A, are at the start of File:MacintoshClassic LogicBoard Schematic.pdf (PDF pp. 1–3 and 4–6), ahead of the logic board, 820-0390-B (PDF pp. 7–11). They were drawn by BOMARC Services from the boards and are not Apple documents.[10] The file File:Classic Analog Board Schematic.pdf is not a Classic document: its internal title is SE30_Analog_Board, and it shows an analogue board fed from a separate power supply, as in the Macintosh SE/30.
Maintenance, capacitors and troubleshooting
[edit | edit source]- Macintosh Classic / Classic II General Maintenance: cleaning, the lithium battery and its 3.0 V replacement threshold, and the rails.
- Macintosh Classic Capacitor Replacement Guide: values and positions.
- Macintosh Classic / Classic II Troubleshooting: symptom-led diagnosis.
- CRT Discharge Procedure: read before opening the case.
- Retrobrite: for a yellowed case.
The Dead Mac Scrolls, a component-level reference for the earlier compacts, does not cover the Classic: its author says the Classic, Classic II and other machines still under warranty when it was written are not covered in that edition.[11]
Sad Mac codes are decoded on Sad Mac Error Codes and with the Sad Mac Decoder.
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 Mac Classic, Low End Mac—link(accessed 2026-09-30) Dates, prices, code names XO and Civic, order number M0420, System 6.0.7 to 7.5.5, ROM disk, brightness control panel, memory card.
- ↑ 2.0 2.1 2.2 2.3 Apple Computer, Macintosh Classic/Classic II/Performa 200 Service Source, Specifications, pp. 1-8 (PDF pp. 5-12). Hosted as File:Classic ii.performa 200.pdf; see Macintosh Classic/ Classic II/Performa 200 Service Source.
- ↑ 3.0 3.1 Macintosh Classic/Classic II/Performa 200 Service Source, Exploded View (PDF p. 115).
- ↑ Macintosh Classic/Classic II/Performa 200 Service Source, Upgrades, Memory Expansion Board and Memory Upgrade, pp. 1-6 (PDF pp. 68-73).
- ↑ Macintosh Classic/Classic II/Performa 200 Service Source, Troubleshooting, Symptom Charts, Miscellaneous, pp. 12-14 (PDF pp. 25-27).
- ↑ Macintosh Classic/Classic II/Performa 200 Service Source, Additional Procedures, Battery Verification, pp. 1-4 (PDF pp. 81-84).
- ↑ Macintosh Classic/Classic II/Performa 200 Service Source, Adjustments, pp. 1-24 (PDF pp. 90-113).
- ↑ Macintosh Classic/Classic II/Performa 200 Service Source, Take Apart, Cover, pp. 1-3 (PDF pp. 30-32).
- ↑ Macintosh Classic/Classic II/Performa 200 Service Source, Take Apart, Power/Sweep Board, pp. 4-11 (PDF pp. 33-40).
- ↑ BOMARC Services, schematics of the "Macintosh Classic" series computer power supply / 9-inch monitor, boards 820-0395-A and 820-0525-A (PDF pp. 1–3 and 4–6), and of the Classic logic board 820-0390-B (PDF pp. 7–11). Hosted as File:MacintoshClassic LogicBoard Schematic.pdf. Reverse-engineered, not Apple documentation.
- ↑ Larry Pina, The Dead Mac Scrolls, Peachpit Press, 1992, Introduction (PDF p. 8). Hosted as File:The Dead Mac Scrolls 1992.pdf; see The Dead Mac Scrolls.