Old Mac of the Month: The Quadra 605

This month’s post is by my friend Thomas Brand. Thomas writes at Egg Freckles, and is running in the St. Jude Marathon on my son’s team. You can learn more and donate here.

The Quadra 605 was the Power Macintosh Cube of the Quadra line. A miniature 32-bit workstation, with limited expandability but powerful specs. Like the Cube it came in a low-profile case that was never used again on any Mac. Unlike the Cube, it was available for a low-price almost anyone could afford.
At $900 USD, the 605 was the Quadra for the rest of us.

The coolest thing about the Quadra 605 was its minimal design. On the machine’s face you will find the classic rainbow Apple logo, the word Macintosh, and the Quadra 605 name badge. There is a slot for the floppy drive, a paperclip ejection hole, and that’s it. No flashing lights, knobs, or buttons. No plastic cover concealing a vacant drive bay.

The Quadra 605 was a minimal Mac before its time.

On the back you will find a rocker power switch[1], power connection, and the 605’s seven ports all lined up in a row.

On the far right is the Quadra 605’s only expansion slot, the PDS.
You won’t find a reset, or programmer’s key on this Macintosh.
Exactly what you need, and nothing you don’t.

Inside the case is much of the same.

The entire top unclips in seconds, and inside every component is laid out in a plane – nothing is above or underneath anything else, there’s no remove-the-HD-before-the-motherboard-comes-out nonsense. The best feature however – no screws on the inside. Everything clips in or out all the way from the speaker & floppy drive, to the motherboard & power supply. These boxies are a dream to work on!.

The Quadra 605 was the easiest Macintosh to ever repair. You don’t have to be a Mac Genius to work on one.

At the center of the 605’s logic board you will find the MC68LC040 CPU. Running at 25 MHz on a 32-bit bus, it had 8 kBs of on-chip L1 cache divided into two banks; 4 kBs for Data and 4 kB for Instructions.[2] Of course the 68LC040 could later be replaced with a full 68040 which included an onboard FPU that tripled the speed of floating point operations.

With 4 MBs of onboard RAM, the Quadra 605 was a usable machine under System 7.1. But in order to make the 605 really sing, you would want to stuff its single 72 pin SIMM socket full of as much memory as you could afford.
The official supported maximum RAM was 36 MBs; including the onboard 4 MBs. But after market SIMMs were also available in capacities as large as 128 MBs; all of which could be used by the Quadra 605.

Video out was supplied by a single DA15F connector, which provided multiple resolutions with up to thousands of colors using the right combination of video memory.

The Quadra 605’s two available video RAM slots could take either two 256 kB 80 ns 68-pin VRAM SIMMs, or two 512 kB SIMMs.
Installing one 512 kB and one 256 kB VRAM SIMM garbled the display.
Dual-monitor configurations were only available using a rare discrete graphics card installed in the Quadra 605’s Processor Direct Slot.

The Quadra 605 shipped with a 1.44 MB SuperDrive standard, and either 80 or 160 MBs of hard drive space. Like all desktop Macs available at the time, it also came with one audio in and one audio out, one 25-pin external DB25F SCSI connector, one 8 pin Mini-DIN Printer port, one 9 pin Mini-DIN Modem port, and a single Apple Desktop Bus connector used for connecting mice, keyboards, and other low-speed low-power peripherals.

Inside the case customers would find the 50 pin internal SCSI connector used by the Quadra 605’s hard drive, and the LC III style 68030-compatible Processor Direct Slot.

While mechanically compatible with the 68030 Processor Direct Slot, the Quadara 605’s PDS is not a true LC PDS. Instead of communicating directly with the processor it worked using emulation. Expansion cards made specifically for 030 processors such as 68881 or 68882 FPUs will not work, but popular cards like the Apple IIe Card, which allowed the 605 to emulate an Apple IIe, will.

The low-profile Quadra 605 had no room for professional full-height NuBus cards, and no chance at becoming a player in the lucrative Desktop Publishing market where expandability was paramount.

However the Quadra 605 was compatible with Apple’s Macintosh PowerPC Processor Upgrade Card which provided a 50 MHz PowerPC 601 CPU.
DayStar Digital and Sonnet manufactured 100 MHz versions of this card which could also be used in the Quadra 605.

Installation of these cards was inconvenient at best, as LC PDS expansion cards had to be removed in order to make room for the processor upgrade.

I remember installing one of the 100 MHz DayStar Digital cards in my Quadra 605. The increase in performance was the most significant upgrade I had ever experienced on a Mac until the introduction of Intel x86 CPUs.

Too bad I had to swap the PowerPC upgrade with the PDS Ethernet Card every time I wanted to get online.

A PowerPC upgrade was an inexpensive way to prolong the life of a Quadra 605, as it enabled it to run Mac OS 8.5 and beyond.
But by the time such upgrade cards hit the market, it was too late to change the Quadra 605’s fate as a unique Mac that never quite made it.

What is a Quadra 605 good for today? Not much.

My Newton MessagePad 2100 has a faster processor with more memory, and can connect to the Internet wirelessly. Your cell phone could run circles around this thing. That being said, no other headless classic desktop Mac looks this good.

The Quadra 605 despite its limitations, is a great way to experience the golden age of Macintosh software in small package that won’t look bad on your desk.[3]

Want to write about an old Mac you love? Get in touch!

  1. No soft power-on from the keyboard for the Quadra 605.  ↩
  2. An L2 cache was possible via the Processor Direct Slot.  ↩
  3. For a glimpse into the life of a real Quadra 605 fan, look no further than Dana’s 605 Obsessions fan page (I rescued it from the depth of Archive.org).  ↩