Macintosh LC III
 | |
| Macintosh LC III (Stephen Edmonds, CC BY-SA 2.5) | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Desktop personal computer |
| Released | 10 February 1993 |
| Discontinued | 14 February 1994 |
| Intro price | US$1,349 (4 MB RAM, 80 MB hard disk) |
| CPU | Motorola 68030 at 25 MHz, 32-bit data path |
| Memory | 4 MB on the logic board plus one 72-pin SIMM slot, 36 MB maximum (80 ns) |
| Storage | 40, 80 or 160 MB internal SCSI hard disk |
| Display | — |
| Sound | 8-bit mono input and output |
| Graphics | Built in (DB-15); 512 KB VRAM on the board, 768 KB with a 256 KB VRAM SIMM |
| ROM | 1 MB |
| FPU / coprocessor | Optional 68882 in a PLCC socket |
| Media | 1.4 MB Apple SuperDrive |
| Ports / interface | ADB, two RS-232/RS-422 serial (mini DIN-8), SCSI (DB-25), video (DB-15), sound in, sound out |
| Expansion | 114-pin processor-direct slot (accepts 96-pin LC cards), 4 W |
| Power | 100–240 V AC auto-configured, 47–63 Hz, 30 W maximum |
| Dimensions | 3.0 × 12.2 × 15.0 in (7.7 × 31.0 × 38.2 cm) |
| Weight | 8.8 lb (4.0 kg) |
| OS / Firmware | System 7.1 to Mac OS 7.6.1 |
| Predecessor | Macintosh LC II |
| Successor | Macintosh LC III+ |
| Model no. | M1254 (Gestalt ID 27) |
The Macintosh LC III is a low-profile desktop Macintosh that Apple sold from February 1993 to February 1994, mainly to education, with the consumer version sold as the Performa 450.[1] It keeps the LC case and power supply but has a 25 MHz 68030 with a 32-bit path to RAM and ROM, a single 72-pin SIMM slot, a socket for a 68882 FPU and a 114-pin processor-direct slot that also takes the 96-pin cards of the LC and LC II. Apple put its overall performance close to that of the Macintosh IIci.[2]
History
[edit | edit source]Apple introduced the LC III and the Performa 450 on 10 February 1993. The LC III was priced at US$1,349 with an 80 MB hard disk.[1] EveryMac lists order number M1312LL/A for the 4 MB, 512 KB VRAM, 80 MB configuration.[3] Apple's Performa 400 series manual lists the Performa 450 with an 80 or 120 MB drive.[4] A 33 MHz version, the Macintosh LC III+, with the Performa 460, 466 and 467, replaced it on 18 October 1993.[1] Apple sold upgrade kits to turn an LC or LC II into an LC III, and an LC III into an LC 475.[5]
Specifications
[edit | edit source]| Item | Figure |
|---|---|
| Processor | Motorola 68030 at 25 MHz, 32-bit internal data bus, burst-mode RAM access, coprocessor socket |
| DRAM | 4 MB standard, expandable to 36 MB (80 ns or faster SIMMs) |
| ROM | Listed as "512K expandable to 1 MB"; see below |
| VRAM | 512K on board, upgradable to 768K |
| Floppy drive | 1.4 MB Apple SuperDrive |
| Hard drive | 40, 80 or 160 MB |
| Serial | Two RS-232/RS-422 ports, mini DIN-8 |
| Sound | Mono input and output ports (mini phono); 8-bit input at 11 or 22 kHz; monophonic 8-bit generator feeding the same signal to both channels |
| Video | DB-15; up to 16-bit colour on 12-, 13- and 16-inch monitors (see the table below for VRAM needs), 8-bit on the 15-inch portrait and 21-inch; NTSC and PAL |
| Expansion | 114-pin processor-direct slot for 020 or 030 direct-slot cards |
| Power | 100–240 V AC, automatically configured, 47–63 Hz; 30 W maximum, not including the monitor |
| Size and weight | 3.0 × 12.2 × 15.0 in (7.7 × 31.0 × 38.2 cm); 8.8 lb (4.0 kg) |
The LC series manual prints "512K expandable to 1 MB" of ROM for the LC III, LC 475 and Quadra 605.[5] Apple's LC III developer note and the Performa 400 series manual give 1 MB: two 40-pin 256K × 16 chips on the logic board.[2][4]
Hardware
[edit | edit source]Logic board and chips
[edit | edit source]Recap-a-Mac's photographed board is marked 820-0650-B, copyright 1992; Console5 lists 820-0650-A and -B.[6][7] The design is built around Sonora, a custom chip that combines the functions of the LC II's V8 gate array and SWIM floppy controller (as SWIM2) with more video modes, and Omega, a programmable clock generator. The 68HC05 microcontroller from the LC and LC II handles ADB, the real-time clock, parameter RAM, power-on reset and the keyboard reset and NMI.[2]
Memory
[edit | edit source]The board has 4 MB of RAM (eight 1M × 4 chips) and one 72-pin SIMM socket for a 1, 2, 4, 8, 16 or 32 MB SIMM, giving 36 MB. The SIMM must be 80 ns fast page mode and built to Apple's LC III specification, which calls for tin contacts, not gold, and dedicated power and ground layers; Apple warns that a SIMM outside the specification can cause system errors. In 24-bit addressing mode only 8 MB can be used.[2]
Video
[edit | edit source]The frame buffer is 512 KB of VRAM soldered to the board, and a 68-pin socket takes a 256 KB VRAM SIMM of 80 ns parts for 768 KB; a larger SIMM gives no more memory. The VRAM path is 16 bits wide.[2]
| Monitor | Resolution | 512 KB VRAM | 768 KB VRAM |
|---|---|---|---|
| 12-inch RGB | 512 × 384 | 16-bit | 16-bit |
| 13-inch RGB | 640 × 400 | 16-bit | 16-bit |
| 13-inch RGB | 640 × 480 | 8-bit | 16-bit |
| VGA | 640 × 480 | 8-bit | 16-bit |
| Portrait | 640 × 870 | 4-bit | 8-bit |
| 16-inch RGB | 832 × 624 | 8-bit | 8-bit |
The 640 × 400 mode, chosen in the Monitors control panel, gives 16-bit colour on 13-inch and VGA monitors without extra VRAM.[2]
Floating-point unit
[edit | edit source]The board has a PLCC socket for an optional 68882. Apple's developer note says some configurations may have been shipped with an FPU fitted.[2] Recap-a-Mac's photographed board has the socket empty.[6]
Expansion slot
[edit | edit source]The 114-pin processor-direct slot is notched to take the 96-pin cards made for the LC and LC II; LC cards work if they are compatible with the 68030. Apple limits a card to 4 W in total, with at most 800 mA at +5 V, 20 mA at −5 V and 165 mA at +12 V, and recommends that cards ground the /FANSPEED signal for extra cooling.[2]
Battery, power supply and capacitors
[edit | edit source]The PRAM battery is Apple part 742-0011, a lithium cell (3.6 V according to EveryMac); Apple replaces it below 3.0 V.[5][3] The power supply is 661-1733, shared with the whole LC family.[5] The ADB port supplies up to 200 mA at +5 V through a 1 A fuse.[2]
The logic board has eleven surface-mount electrolytic capacitors. One of them, C22 on the −5 V rail, was fitted the wrong way round at the factory, matching an error in the board's silkscreen; replacements must go in the opposite way to the silkscreen marking.[6][8] See Macintosh LC III Capacitor Replacement Guide.
Service notes
[edit | edit source]- There are no programmer's switches. Command-Power sends an NMI and Command-Control-Power forces a hard reset; hold the keys for at least a second.[2]
- The LC III uses the LC family's error chords: an eight-tone chord at startup points to the SIMMs.[5]
- A machine that shuts down or restarts intermittently may be in thermal shutdown: check the vents on the back and top of the case; it should recover after 30 to 40 minutes.[5]
- The fan goes back logo side down; Apple warns that otherwise it may damage the computer.[5]
- DRAM SIMMs from an LC do not fit the LC III. When an LC is upgraded, its VRAM SIMM and expansion card move to the LC III board.[5]
Routine care is on Macintosh LC III General Maintenance and diagnosis on Macintosh LC III Troubleshooting.
Documentation
[edit | edit source]- Macintosh LC Series/Quadra 605 Service Source: Macintosh LC Series/ Quadra 605 Service Source
- Macintosh Performa 400 Series Service Source: Macintosh Performa 400 Series Service Source
- Macintosh LC III Developer Note: Macintosh LC III Developer Note
Related pages
[edit | edit source]- Macintosh LC III General Maintenance
- Macintosh LC III Troubleshooting
- Macintosh LC III Capacitor Replacement Guide
- Macintosh LC II
- Macintosh LC III+
- Macintosh Performa 450
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Macintosh LC III, Wikipedia—link(accessed 2026-09-30) Sold February 1993 to February 1994; US$1,349 with an 80 MB hard disk; Performa 450 introduced 10 February 1993; LC III+ and Performa 460/466/467 introduced 18 October 1993.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Apple Computer, Macintosh LC III Developer Note (1993), File:Macintosh LC III Developer Note.pdf (see Macintosh LC III Developer Note): chapter 1, pp. 2-9 (features, design differences, compatibility, Sonora, ROM, RAM), pp. 14-15 (VRAM, Table 1-4 video modes), p. 28 (ADB), p. 29 (keyboard reset and NMI, PDS), p. 37 (Table 1-16 PDS power budget); chapter 2, p. 42 (Gestalt ID, System 7.1).
- ↑ 3.0 3.1 Apple Macintosh LC III Specs, EveryMac—link(accessed 2026-09-30) Introduced 10 February 1993, discontinued 14 February 1994; model M1254, Gestalt ID 27, order number M1312LL/A; 3.6 V lithium battery; System 7.1 to 7.6.1.
- ↑ 4.0 4.1 Apple Computer, Macintosh Performa 400 Series Service Source, File:Performa 400 series.pdf (see Macintosh Performa 400 Series Service Source), Specifications, PDF pp. 3-15.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 Apple Computer, Macintosh LC Series/Quadra 605 Service Source, File:Quadra 605.lc series.pdf (see Macintosh LC Series/ Quadra 605 Service Source): Specifications, PDF pp. 6-17; symptom charts, PDF pp. 20-36; Take Apart, PDF pp. 38-63; Upgrades, PDF pp. 71-86; Battery Verification, PDF pp. 106-107; Exploded View, PDF p. 112.
- ↑ 6.0 6.1 6.2 Macintosh LC III (Performa 450), Recap-a-Mac—link(accessed 2026-09-30) Annotated photograph of logic board 820-0650-B, hosted here as File:Mac LC III Recap Guide.jpg; note on the reversed capacitor C22.
- ↑ Macintosh LC Series, Console5 TechWiki—link(accessed 2026-09-30) Section "LC III Logic Board: 820-0650-A / 820-0650-B".
- ↑ Doug Brown, "The capacitor that Apple soldered incorrectly at the factory", 26 November 2024.
