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Apple Macintosh Quadra 650

In the early 1990s, the processor wars were heating up. Intel was establishing its dominance thanks to its 80486 processor. Motorola had kept pace early on, moving briefly from the 68000 to the 68020, then finding success with the 68030 chips, providing a migration path for the Macintosh, Amiga, Atari, and Sharp systems. But Motorola’s third-generation 68040–with its onboard cache, floating-point, and memory management capabilities–lifted Apple’s prospects and prompted a new line of computers: the Quadra.

The Macintosh Quadra holds a special place in my Apple history. During the ‘90s, I supported hundreds of Macs at a small college, and I was lucky to use a Quadra 840AV regularly. I always admired the Quadra line and now recognize it was the high-water mark for twentieth-century Macintoshes.

In late 1991, Apple released the first two Quadras. The 700 was housed in a case reminiscent of the IIcx and IIci, and the Quadra 900 was Apple’s first tower computer. A few months later, Apple replaced the 900 with the larger and faster Quadra 950. Not long after, the 700 was replaced with the Quadra 800. Then things got complicated.

Across the Macintosh desktop lineup, the Quadras were Apple’s top-of-the-line systems, with the nostalgic Classics at the bottom and color LCs marketed for education and budget-minded consumers. To compete with the rise of Windows-capable PCs on business desktops, Apple added the Centris line in 1993, creating a mid-level between the Quadras and LCs. (At the same time, Apple created the Performa name for marketing directly to consumers through big-box retailers, but I’ll skip over that confusion.)

The brief Centris line only had three systems: the 610, the 650, and the 660AV. The Centris 650 incorporated the case design of the short-lived Macintosh IIvx—the last Macintosh II. Aside from its unique case, the IIvx was the first Macintosh with a built-in CD drive. While the IIvx was outfitted with a 68030 processor running at 33MHz (though with a limited 16MHz bus), the Centris 650 sported the newer 68040 processor running at 25Mhz. Despite its obvious connection to the IIvx, Apple really hoped the 650 would replace the recently-retired but well-regarded Macintosh IIci.

The Centris 650 was released in February 1993, but by October, the computer was renamed the Quadra 650. During the transition, the 650’s processor was sped up to an impressive 33MHz with an 8K level one cache. Thanks to the speed boost, the now-Quadra 650 rivaled and essentially replaced the Quadra 800.

The 650 provides three NuBus and one Processor Direct Slot. Maxed out, it can support an impressive 136MB of RAM (using the new-at-the-time 72-pin SIMMs) and 1MB of VRAM. It has a floppy drive and SCSI hard drive, and like the IIvx, it could be outfitted with a built-in 2x CD-ROM. Peripherals connect through two ADB ports, serial modem and printer ports, and an external SCSI interface. Important for its intended business use, the Quadra 650 also came with a built-in 10Mbps Ethernet connection.

I picked up my Quadra 650 from eBay. While looking for the highly-desired 700 or 800 models, I came across this 650, which looked to be in good condition. I won the auction with a reasonably-priced bid, and my only regret was its lack of a built-in CD drive. While it’s possible to add a working drive, it is a challenge to find a matching front bezel.

I was pleasantly surprised when I opened the case and saw no electrolytic capacitors. While this computer was produced during the era of notoriously bad caps, Apple released a few systems with tantalum capacitors instead of aluminum electrolytic. Tantalums can short (sometimes violently), but they do not leak, and that makes them a welcome sight on any Macintosh logic board. I was even happier when I removed the drive cage and saw an intact PRAM battery. The greatest danger to aging Macintoshes is the small lithium battery that preserves system settings. Such time bombs often leak and destroy nearby components with battery acid.

While the logic board was free of electrolytic caps, the power supply was not. I opened the PSU and saw things were in relatively good order. There was a hot spot where a resistor had scorched the board, but after cleaning, I decided to leave the PSU alone for now. At some point, I will likely come back and replace the capacitors and address the hot resistor.

This Quadra 650 came with 8MB of RAM soldered to the logic board. I retrieved two additional 8MB SIMMs to provide a total of 24MB of system memory, and I placed an order with @Siliconinsid for two 256K VRAM modules that doubled the onboard video memory to the maximum 1MB, providing 16-bit color.

The single drive included in the system was a standard 1.44MB “SuperDrive” common in all Macintoshes at the time. I cleaned and lubricated the floppy drive and reinstalled it.

The eBay seller had removed the hard drive, so I needed a replacement. While I’ve used SCSI2SDs in the past, this time, I decided to try the newer and less expensive BlueSCSI solution. I purchased a kit and assembled it myself. The instructions were clear and helpful, and I was pleased with the outcome. The reasonable price and straightforward assembly process mean there will be more BlueSCSI builds in the future.

Compared to the SCSI2SD, the BlueSCSI provides a better means to manipulate drive images. An image file can be opened on a modern computer using a Macintosh emulator and files conveniently copied or software installed. The image file can then be copied back to an SD Card and inserted into the BlueSCSI. After a little trial and error, I found success in prepping image files as follows: First, I formatted the SD card using the format utility provided by the SD Association, then I replaced the FAT file format with ExFAT to improve performance. I then downloaded several blank drive images and loaded one into my Basilisk II emulator. I then used the Wish I Were control panel to make my emulated system report to be a Quadra 650. Finally, I fired up the System 7.5.3 installer from the Apple Legacy Software Recovery CD. After selecting the “System Software for this Macintosh” option, I had an image file ready to boot.

I attached the BlueSCSI to the empty drive bay and turned my attention to the monitor. About a year ago, I acquired a large collection of Apple products from a gentleman readying for retirement. Within the collection was a dirty and yellowed Apple Color Plus 14-inch display. Also released in October 1993, it seemed fitting to pair the display with the Quadra 650–though it typically accompanied less-expensive Performa models. The Goldstar shadow-mask CRT has a fixed resolution of 640×480.

I’m not ordinarily bothered by moderate yellowing, but this monitor was disturbingly yellow. So, I decided this would be my first attempt at retrobriting something large. I was planning to submerge the plastic in a clear tub with liquid hydrogen peroxide, but I could not locate the desired concentration quickly. So instead, I applied a retrobrite cream I acquired after hearing it described at a 2020 Kansasfest presentation.

I dismantled the display and thoroughly cleaned the plastic. I was nervous about marbling if the hydrogen-peroxide-infused cream was not applied consistently, so I decided to reapply fresh cream every 20 to 30 minutes. After several hours of exposure to the hot summer sun, the parts were not fully restored, but they were much better and more in line with the yellowing commonly seen on vintage computers.

I rushed to reassemble the display while I still remembered how it fit together. I was generally pleased with the aesthetic improvement, but I was eager to test it with the Quadra 650. At first, I was confused because after powering the display, the screen would turn off immediately when I plugged the display cable into the 650. After a moment of confusion, I realized the monitor worked normally once I powered on the Quadra. Apparently, the display’s energy-saving feature shuts down the CRT if the attached computer is not running.

Once fully reassembled, I was pleased with the system. It boots quickly and runs software of the era without difficulty. Thus far, aside from installing Microsoft Office 4.2 and a few games, I’ve used ZTerm to “dial” into the Captain’s Quarter II BBS with my retroNET WiFi modem.

The Quadra 650 is fast enough to satisfy any early Mac user’s dreams. I wasn’t specifically looking for a 650, but it’s often available and faster than the fan-favorite 700. I would love to use the revered 840AV again, but it is almost impossible to find and often damaged by capacitor leakage. So, I am delighted to have a capable Quadra 650 in my collection.

Published inMacintosh


  1. Marcus Marcus

    Had one of these also. Was bulletproof and never let me down. Do have to admit however, that I do not miss the beige box asthetic at all.

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