Macintosh 512K
 | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal computer |
| Released | September 1984 |
| Discontinued | April 1986 |
| Intro price | US$3,195 |
| CPU | Motorola 68000 @ 7.83 MHz |
| Memory | 512 KB, soldered, not user-expandable |
| Storage | Internal single-sided 400 KB 3.5-inch floppy drive |
| Display | 9-inch monochrome CRT, 512 × 342 pixels |
| Sound | Four-voice, 8-bit D/A conversion, 22 kHz sampling |
| ROM | 64 KB |
| Ports / interface | DB-19 external floppy; DE-9 mouse; RJ-11 keyboard; 2 × RS-232/RS-422 serial (DE-9) |
| Power | 105–125 V AC, 50–60 Hz, 60 W maximum |
| Dimensions | 13.6 in H × 9.6 in W × 10.9 in D (34.5 × 24.4 × 27.6 cm) |
| Weight | 16 lb 8 oz (7.5 kg) |
| OS / Firmware | System 1.1 – System 4.1 |
| Predecessor | Macintosh 128K |
| Successor | Macintosh 512Ke |
| Codename | Fat Mac |
| Model no. | M0001W |
The Macintosh 512K was introduced in September 1984 as a Macintosh 128K with four times the memory. Everything else — the 68000 processor, the 64 KB ROM, the 9-inch monochrome screen and the single-sided 400 KB floppy drive — is the same, and Apple services the two machines from a single manual.[1] It sold for US$3,195 and was nicknamed the Fat Mac.[2]
The extra memory made the machine usable with the larger applications of the period, but it still had no internal hard disk, no SCSI port and no memory expansion: the RAM is soldered down. The Macintosh Plus addressed all three.
Maintenance
[edit | edit source]The 512K is mechanically and electrically the same machine as the 128K, so its servicing, board layout and schematics are shared. See Macintosh 128K/512K General Maintenance and the Macintosh 128K page.
The machine contains a CRT; read CRT Discharge Procedure before opening the case.
Specifications
[edit | edit source]Every figure in this table is from Apple's own specification pages for the 128K/512K.[1]
| Item | Specification |
|---|---|
| CPU | Motorola 68000, 7.83 MHz |
| RAM | 512 KB (the same manual covers the 128 KB machine) |
| ROM | 64 KB |
| PRAM | CMOS custom chip with 256 bytes of parameter memory, backed by a 4.5 V user-replaceable battery |
| Floppy drive | Internal single-sided 3.5-inch drive, 400 KB |
| External floppy | DB-19 connector |
| Mouse | DE-9 connector; mechanical tracking, optical shaft encoding at 3.54 pulses per mm |
| Keyboard | 58 keys, software mapped, RJ-11 connector |
| Serial | Two RS-232/RS-422 ports, DE-9 connectors |
| Sound | Four-voice, 8-bit digital/analogue conversion, 22 kHz sampling rate |
| Video | 9-inch diagonal screen, 512 × 342 bit-mapped display |
| Line voltage | 105–125 V AC, 50–60 Hz |
| Maximum power | 60 W |
| Dimensions | 13.6 × 9.6 × 10.9 in (34.5 × 24.4 × 27.6 cm) |
| Weight | 16 lb 8 oz (7.5 kg) |
Memory
[edit | edit source]The 512 KB is soldered to the logic board. Apple offered no memory upgrade for this machine, and the RAM configuration is fixed in the logic that decodes it; period third-party boards that fitted Macintosh Plus ROMs and more memory existed, but they are logic board modifications rather than upgrades.[2] The Macintosh Plus, which introduced the four 30-pin SIMM sockets used across the rest of the compact family, is documented on the Macintosh Plus Memory Upgrade Guide.
Power rails
[edit | edit source]Unlike the later compacts, this generation does have a published voltage adjustment. Apple's procedure connects the Macintosh voltage test cable (part number 077-0135) to the external floppy port and adjusts the regulator on the power/sweep board for 11.90–12.75 V on the orange lead and 4.85–5.15 V on the red lead; if both cannot be brought inside those windows the board is replaced.[1] The full procedure, with its warnings, is written up on Macintosh Plus General Maintenance, which uses the same board family.
Known board-level faults
[edit | edit source]The Dead Mac Scrolls documents two faults that present as software problems:[3]
- A 512K or 512Ke that resets a directly connected ImageWriter II on the printer port, or that never appears on an AppleTalk network, usually has a failed 26LS30 line driver at board location B6.
- On an original 128K analogue board that has been paired with an upgraded logic board, repeatable system errors that no other Macintosh shows are a low +5 V rail; the overvoltage reference diode (1N5349B) at CR18 is the part to check.
Related pages
[edit | edit source]- Macintosh 128K
- Macintosh 512Ke
- Macintosh Plus
- Macintosh 128K/512K General Maintenance
- Sad Mac Error Codes and the Sad Mac Decoder
- CRT Discharge Procedure
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Apple Computer, Macintosh 128K/512K Service Source — Specifications, Take Apart and Adjustments chapters. Hosted on this wiki: File:Macintosh 128k.512k.pdf.
- ↑ 2.0 2.1 apple-history.com, Macintosh 512K (secondary source, used for the introduction price, codename and market dates).
- ↑ Larry Pina, The Dead Mac Scrolls, Peachpit Press, 1992, "Early Macs" chapter. Hosted on this wiki: File:The Dead Mac Scrolls 1992.pdf.