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Macintosh Quadra 605

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Macintosh Quadra 605
Macintosh Quadra 605
Specifications
ManufacturerApple Computer, Inc.
TypePersonal Computer
ReleasedOctober 21, 1993
DiscontinuedOctober 17, 1994
Intro priceUS$900 (4 MB/80 MB), US$1,300 (8 MB/160 MB)
CPUMotorola 68LC040 @ 25 MHz
Memory4 MB RAM soldered + 1 SIMM slot (up to 36 MB)
Storage80 MB or 160 MB SCSI hard drive, 1.44 MB floppy
Display512×384 to 1152×870
Sound8-bit stereo
Dimensions2.9" H × 12.2" W × 15.3" D (7.4 × 31 × 38.9 cm)
Weight8.8 lbs (4 kg)
OS / FirmwareSystem 7.1 – Mac OS 8.1
Model no.M1476

The Macintosh Quadra 605 is a personal computer introduced by Apple Computer on October 21, 1993.[1] It was the smallest and least expensive member of the Quadra line, housed in a compact "pizza box" case shared with the LC series.

The Quadra 605 targeted business users, while Apple sold essentially the same hardware to educational markets as the LC 475 and to consumers as the Performa 475 and Performa 476.[2] All three product lines share the same logic board design.

Model Variants

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The Quadra 605 shares its logic board with several other Apple models:

  • LC 475 – Education market variant
  • Performa 475 – Consumer market variant
  • Performa 476 – Consumer market variant (bundled with different software/peripherals)

The primary differences between these models are case color, bundled software, and distribution channel. The LC 475 case has a slightly different appearance, but the internal hardware is identical.

Architecture and Processor

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The Quadra 605 uses a Motorola 68LC040 processor running at 25 MHz.[3] The "LC" designation indicates this is a cost-reduced version of the 68040 that lacks a floating-point unit (FPU). The processor is socketed and can be upgraded to a full 68040 with FPU, or to a PowerPC 601 via third-party upgrade cards.

The system bus runs at 25 MHz. The 68LC040 includes 8 KB of on-chip cache. An optional 256 KB L2 cache card could be installed on a riser card that plugged into the CPU socket.

ROM and System Software

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The Quadra 605 contains a 1 MB ROM. It shipped with System 7.1 and officially supports up to Mac OS 8.1.

Memory and Storage

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RAM Configuration

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The Quadra 605 has 4 MB of RAM soldered to the logic board. A single 72-pin SIMM slot allows expansion. Apple officially supports up to 32 MB SIMMs for a maximum of 36 MB total RAM. Third-party testing has demonstrated compatibility with 128 MB SIMMs, allowing up to 132 MB total.

RAM must be 80 ns or faster.

Storage Systems

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The Quadra 605 shipped with either an 80 MB or 160 MB internal SCSI hard drive. A single 1.44 MB 3.5" manual-inject floppy drive is standard. External SCSI devices can be connected via the rear panel SCSI port.

Display and Graphics

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The Quadra 605 has dedicated video with two VRAM SIMM slots. Standard configuration includes 512 KB of VRAM (two 256 KB SIMMs). Upgrading to 1 MB (two 512 KB SIMMs) increases color depth at higher resolutions.

Video Capabilities
VRAM Resolution Color Depth
512 KB 512×384 16-bit (Thousands)
512 KB 640×480 8-bit (256 colors)
512 KB 832×624 8-bit (256 colors)
512 KB 1024×768 4-bit (16 colors)
1 MB 832×624 16-bit (Thousands)
1 MB 1024×768 8-bit (256 colors)
1 MB 1152×870 8-bit (256 colors)

A second display can be supported by adding an LC III PDS video card.

Input/Output and Expansion

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Port Configuration

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  • 1× Apple Desktop Bus (ADB) for keyboard and mouse
  • 2× Serial ports (printer and modem)
  • 1× SCSI port (external)
  • 1× Video port (DB-15)
  • 1× Audio in (3.5mm)
  • 1× Audio out (3.5mm)

Expansion

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The Quadra 605 includes a single LC III PDS slot. However, in practice this slot is largely inaccessible due to the compact case design – installing PDS cards requires significant modification. The slot shares the same pinout as the LC III PDS.

Power Supply

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The Quadra 605 uses the same compact power supply as the LC, LC II, LC III, and LC 475. The power supply accepts 100V-240V AC at 47-63 Hz and draws a maximum of 30 watts. This shared power supply design means capacitor replacement guides for the LC series apply to the Quadra 605.

General Maintenance

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For detailed maintenance practices including cleaning, PRAM battery management, connector corrosion prevention, and voltage adjustments, refer to the dedicated Macintosh Quadra 605 General Maintenance page.

Capacitor Replacement Guide

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Detailed capacitor replacement guidelines for the logic board and power supply can be found on the Macintosh Quadra 605 Capacitor Replacement Guide page.

Troubleshooting

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A comprehensive troubleshooting guide addressing common issues including startup problems, video issues, and component failures is available on the Macintosh Quadra 605 Troubleshooting page.

Technical Details

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System Architecture at a Glance

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Sub-system Specification
CPU Motorola 68LC040 @ 25 MHz
FPU None (LC variant)
Bus width 32-bit data, 32-bit address
System Bus 25 MHz
ROM 1 MB
RAM 4 MB soldered + 1 SIMM slot (max 36 MB official, 132 MB tested)
L1 Cache 8 KB (on-chip)
L2 Cache Optional 256 KB (riser card)
Video 512 KB – 1 MB VRAM, up to 1152×870
Sound 8-bit stereo input/output
Storage SCSI internal/external, 1.44 MB floppy
Expansion 1× LC III PDS (limited accessibility)
Power 30W max, 100-240V AC

Gestalt ID and Model Numbers

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Identifier Value
Apple Model No. M1476
Apple Order No. M1821LL/A
Gestalt ID 89
PRAM Battery 3.6V Lithium

Service Documentation

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The official Apple Service Source documentation for this model:

See Also

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References

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  1. Macintosh Quadra 605 Specs, EveryMac.com—link(accessed 2026-02-10)
  2. Quadra 605, Apple History—link(accessed 2026-02-10)
  3. Macintosh Quadra 605 Specs, EveryMac.com—link(accessed 2026-02-10)