Macintosh Performa 476
The Macintosh Performa 476 is a consumer-oriented personal computer released by Apple in October 1993.[1] It shares the same logic board and compact "pizza box" enclosure as the Quadra 605 and LC 475, distinguished from the Performa 475 by its larger 230 MB hard drive and regional availability.
 | |
| Macintosh Performa 476 | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Personal Computer |
| Released | October 21, 1993 |
| Discontinued | October 17, 1994 |
| Intro price | US$1,460 |
| CPU | Motorola 68LC040 @ 25 MHz |
| Memory | 4 MB RAM (expandable to 36 MB) |
| Storage | 230 MB IDE hard drive, 1.44 MB floppy |
| Display | Supports 640×480 16-bit, 832×624 8-bit |
| Sound | Apple Sound Chip, stereo 16-bit |
| Dimensions | 2.9" H × 16.5" W × 12.6" D |
| Weight | 8.0 lbs (3.6 kg) |
| OS / Firmware | System 7.1 – Mac OS 8.1 |
| Successor | Performa 580 |
| Codename | Aladdin |
| Model no. | M1476 |
The Performa 476 was bundled with 4 MB of RAM, a 230 MB hard drive, and consumer software including ClarisWorks, At Ease, and various entertainment titles. Like its siblings, it features a Motorola 68LC040 processor running at 25 MHz—the "LC" variant lacking the integrated floating-point unit found in the full 68040.
Model Variants
The Performa 476 is one of several models based on identical hardware:
- Quadra 605 — Business/professional variant
- LC 475 — Education market variant
- Performa 475 — Consumer variant (160 MB HD)
- Performa 476 — Consumer variant with larger storage (this model)
All share the same logic board, making maintenance and troubleshooting procedures interchangeable.
Architecture and Processor
The Performa 476 uses the Motorola 68LC040 processor clocked at 25 MHz. The 68LC040 is a cost-reduced version of the 68040, with the floating-point unit disabled. Software requiring FPU functionality requires third-party software emulation.
The processor connects via a 32-bit data bus and 32-bit address bus. A 16 KB unified instruction and data cache is integrated into the processor.
Memory and Storage
RAM Configuration
The Performa 476 ships with 4 MB of RAM soldered to the logic board. A single 72-pin SIMM slot accepts modules from 4 MB to 32 MB, allowing a maximum of 36 MB total system RAM.[2]
Storage
A 230 MB IDE hard drive is standard—larger than the 160 MB drive in the Performa 475. The internal 2.5" drive bay accepts IDE drives up to the capacity limits of the System Software version installed. A 1.44 MB SuperDrive provides floppy disk support.
Display and Graphics
Video is provided by an integrated graphics controller with 512 KB of VRAM soldered to the logic board, expandable to 1 MB via a VRAM expansion slot. Display capabilities include:
- 640×480 at 16-bit color (thousands of colors)
- 832×624 at 8-bit color (256 colors) with 1 MB VRAM
An HDI-45 connector provides video output compatible with Apple monitors.
Audio Capabilities
The Apple Sound Chip (ASC) provides 16-bit stereo audio input and output at 22.254 kHz sample rate. A 3.5 mm stereo output jack is located on the rear panel. An internal speaker provides mono audio when headphones are not connected.
Input/Output and Expansion
Port Configuration
- 2× Mini DIN-8 serial ports (printer and modem)
- 1× ADB port (keyboard and mouse)
- 1× HDI-45 video port
- 1× 3.5 mm stereo audio output
- 1× 3.5 mm audio input
Expansion
One LC Processor Direct Slot (LC PDS) provides expansion capability for network cards, video capture cards, and other peripherals. The slot uses the 68040 bus protocol rather than the NuBus protocol found in higher-end Macintosh systems.
General Maintenance
For detailed maintenance practices including cleaning, PRAM battery management, connector corrosion prevention, and general care, refer to the dedicated Macintosh Quadra 605 General Maintenance page. The Performa 476 shares identical internal hardware with the Quadra 605.
Capacitor Replacement Guide
Electrolytic capacitors on the logic board require replacement after approximately 30 years. Detailed capacitor specifications and replacement procedures can be found on the Macintosh Quadra 605 Capacitor Replacement Guide page.
Troubleshooting
A comprehensive troubleshooting guide addressing common issues including startup problems, video issues, and Sad Mac errors is available on the Macintosh Quadra 605 Troubleshooting page.
Technical Details
System Architecture at a Glance
| Sub-system | Specification (Macintosh Performa 476, October 1993) |
|---|---|
| CPU | Motorola 68LC040 @ 25 MHz |
| FPU | None (LC variant) |
| Bus width | 32-bit data • 32-bit address |
| L1 Cache | 16 KB unified (on-chip) |
| RAM | 4 MB soldered + 1× 72-pin SIMM (max 36 MB) |
| VRAM | 512 KB (expandable to 1 MB) |
| Storage | 230 MB IDE, 1.44 MB floppy |
| Ports | 2× Serial, 1× ADB, HDI-45 video, Audio I/O |
| Expansion | 1× LC PDS |