Quadra 605

What was the smallest desktop Mac prior to the Mac mini? Apple’s LC series, which measured just under 3″ tall, although it had as big a footprint as four Minis. And the Quadra 605 (also known as the LC 475 and Performa 475 or 476) was the most powerful model in this diminutive line.

Quadra 605Apple completed the LC line with what could have been called the LC IV. As with its ancestors, the Quadra 605 was designed to be inexpensive. It shares many components with previous LC models, although it uses a new (equally compact) case that’s flat rather than angled upward in the front. To reduce cost and power use, Apple used the 68LC040 CPU, helping to make this the first Quadra to sell for under US$1,000. For compatibility, it retains the LC expansion slot.

The Performa 475 and 476 differed in the size of the hard drive that shipped with them; the 475 had a 160 MB drive, while the 476 had 230 MB. The Quadra 605 has a different Gestalt ID than the LC and Performa versions.

Probably the most cost effective Quadra 605 upgrade is replacing the FPU-less processor with a full fledged 68040. This makes complex calculations over three times faster and also improves performance with some graphics programs. Both 25 and 33 MHz 68040 processors are often available on the used market (the 605 will accept a 33 MHz CPU but only run it at 25 MHz). However, the heat sink may prevent you from closing the lid.

A dead or low-voltage PRAM battery can temporarily kill off built-in video – see Macintosh Computers: Low Battery Can Cause No Video for more information.


  • Performas introduced 1993.10.18; discontinued
  • LC 475 introduced 1993.10.21 at $900; discontinued 1996.07.15
  • Quadra 605 introduced 1993.10.21 at $900; discontinued 1994.10.17
  • requires System 7.1 or later; highest version supported without a PPC upgrade is Mac OS 8.1.
  • CPU: 25 MHz 68LC040 (one reader reported the Canadian Quadra 605 runs at 33 MHz)
  • FPU: none, 68LC040 can be replaced with 68040 CPU
  • CPU performance: 10.3 (relative to SE); 0.88, Speedometer 4.06; 7.08, MacBench 2.0 CPU; 22 MIPS (see benchmark page for more details); 4074 (68040 upgrade) Whetstones
  • ROM: 1 MB
  • RAM: 4 MB on motherboard, expandable to 132 MB using a single 80ns 72-pin SIMM; can use 1 MB, 2 MB, 4 MB, 8 MB, 16 MB, 32 MB, 64 MB or 128 MB SIMM (Apple’s memory guide indicates double sided SIMMs can be used, but only with 2, 4, and 32 MB capacity), be sure to specify what computer 64 MB and 128 MB SIMMs will be used in — some designs are not compatible. (The 605/475 works only with single-banked 64 MB SIMMs, but it does not work with double-banked 64 MB RAM SIMMs.
  • video: 512 KB VRAM, expandable to 1 MB (remove both 256K VRAM SIMMs, plug in 512K replacements; supports 512 x 384, 640 x 480, 640 x 870, 832 x 624, 1024 x 768, and 1152 x 870 resolutions. We have a field report of an 800 x 600 option as well.
  • L2 cache: optional, PDS
  • ADB: 2 ports for keyboard and mouse
  • serial: 2 DIN-8 RS-422 ports on back of computer
  • SCSI: DB-25 connector on back of computer
  • Hard drive: 80, 160, or 250 MB
  • one LC PDS slot
  • size (HxWxD): 2.9″ x 12.2″ x 15.3″
  • Weight: 8.8 lbs.
  • PRAM battery: 3.6V half-AA
  • Gestalt ID: 89 for LC 475 and Performa, 94 for Quadra 605
  • addressing: 24-bit or 32-bit
  • upgrade path: Power Mac card

Accelerators & Upgrades

Online Resources


  • Apple discontinued support and parts orders for this model on 2001.10.15 (2001.10.22 in Canada). You may be able to find dealers with parts inventory either locally or on our parts and service list.
  • You must have a “fat” system installed to use a PowerPC upgrade.
  • Serial port normally restricted to 57.6 kbps; throughput with a 56k modem may be limited. See 56k modem page. For more information on Mac serial ports, read Macintosh Serial Throughput.
  • Apple recommends using only SIMMs with chips on one side except in 2 MB, 4 MB, and 32 MB sizes.

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