Macintosh LC III
 | |
| Macintosh LC III | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal Computer |
| Released | February 10, 1993 |
| Discontinued | February 14, 1994 |
| Intro price | US$1,349 |
| CPU | Motorola 68030 @ 25 MHz |
| Memory | 4 MB RAM (expandable to 36 MB) |
| Storage | 80 MB SCSI HDD, 1.44 MB SuperDrive |
| Display | 640×480 8-bit (512K VRAM) or 16-bit (768K VRAM) |
| Sound | 8-bit stereo input/output |
| Dimensions | 2.9" H × 12.2" W × 15.3" D |
| Weight | 8.8 lbs (4.0 kg) |
| OS / Firmware | System 7.1 – System 7.6.1 |
| Predecessor | Macintosh LC II |
| Successor | Macintosh LC III+ |
| Codename | Vail, Elsie III |
| Model no. | M1254 |
The Macintosh LC III is a personal computer released by Apple on February 10, 1993.[1] The LC III addressed the main performance limitation of earlier LC models by implementing a full 32-bit data bus, providing a substantial performance improvement over the Macintosh LC II.[2]
Model Variants
[edit | edit source]The LC III was sold as the Performa 450 in consumer markets with bundled software.
Architecture and Processor
[edit | edit source]The LC III uses a Motorola 68030 processor running at 25 MHz with a full 32-bit data bus—a significant improvement over the 16-bit bus of the LC and LC II. This change substantially improved memory performance and overall system responsiveness.[3]
The LC III includes a socket for an optional Motorola 68882 FPU (Floating Point Unit), the first LC to offer FPU support.
The Gestalt ID for the Macintosh LC III is 27.
Memory and Storage
[edit | edit source]RAM Configuration
[edit | edit source]The LC III shipped with 4 MB of RAM standard, expandable to 36 MB. A significant change from earlier LCs: the LC III uses a single 72-pin SIMM slot instead of 30-pin SIMM pairs.
| Configuration | SIMM Required |
|---|---|
| 4 MB | 4 MB 72-pin SIMM (or 4 MB onboard) |
| 8 MB | 4 MB onboard + 4 MB SIMM |
| 12 MB | 4 MB onboard + 8 MB SIMM |
| 20 MB | 4 MB onboard + 16 MB SIMM |
| 36 MB | 4 MB onboard + 32 MB SIMM |
Video RAM
[edit | edit source]The LC III includes 512 KB of VRAM onboard, expandable to 768 KB with a 256 KB VRAM SIMM:
- 512 KB VRAM: 640×480 at 8-bit (256 colors)
- 768 KB VRAM: 640×480 at 16-bit (thousands of colors)
ROM
[edit | edit source]The LC III contains 1 MB of ROM, double that of earlier LC models.
Storage Systems
[edit | edit source]Standard storage included:
- 80 MB internal SCSI hard drive
- 1.44 MB SuperDrive
Input/Output and Expansion
[edit | edit source]Port Configuration
[edit | edit source]- 1× Apple Desktop Bus (ADB) port
- 1× External SCSI (DB-25)
- 1× Audio input (3.5mm stereo minijack)
- 1× Audio output (3.5mm stereo minijack)
- 2× Serial ports (Mini DIN-8)
- 1× Video output (DA-15)
Expansion
[edit | edit source]The LC III features a single LC Processor Direct Slot (LC PDS) and an FPU socket (PGA) for the 68882 coprocessor.
General Maintenance
[edit | edit source]For detailed maintenance practices including cleaning, PRAM battery management, and connector care, refer to the dedicated Macintosh LC III General Maintenance page.
Troubleshooting
[edit | edit source]A comprehensive troubleshooting guide addressing common issues with the Macintosh LC III is available on the Macintosh LC III Troubleshooting page.
Capacitor Replacement
[edit | edit source]The Macintosh LC III logic board contains surface-mount electrolytic capacitors that commonly fail due to age. Detailed replacement guidelines can be found on the Macintosh LC III Capacitor Replacement Guide page.
Important: The LC III has a known factory defect where capacitor C22 was installed with reversed polarity due to a silkscreen error. See the capacitor replacement guide for details.
Technical Details
[edit | edit source]| Component | Specification |
|---|---|
| CPU | Motorola 68030 @ 25 MHz |
| FPU | Optional 68882 (socket provided) |
| PMMU | Integrated in 68030 |
| Data Bus | 32-bit |
| System Bus | 25 MHz |
| ROM | 1 MB |
| RAM | 4 MB (max 36 MB) |
| VRAM | 512 KB (max 768 KB) |