The Blue Chip disk drive, officially called the BCD/5.25, was an aftermarket disk drive for Commodore computers, a very close clone of Commodore’s 1541 drive. It was only on the market for about a year, but it’s not as rare as you might expect for such a short-lived drive.
Distribution by Sears
The main reason the Blue Chip disk drive isn’t as rare as it seems like it should be is because Sears sold it in 1986 alongside the Commodore 64 and 128 in stores and in its catalogs. Sears priced it at $180 on page 642 of its 1986 Christmas catalog.
One of my friends told me he also remembers seeing Blue Chip drives for sale at Target, and an acquaintance of both of ours bought one at Dolgin’s, one of my favorite long-gone stores.
Conceptually, the Blue Chip drive resembles the much more common Oceanic 118/ Excelerator Plus drive. It is smaller than a 1541, and has an external power brick to reduce heat. But the industrial design is a bit odd. Where its closest competitor went for a minimalist design, simply encasing the drive mechanism in a plain metal case, Blue Chip encased its drive in plastic. But the industrial design looks like a mutant Commodore 1571 with shoddier fit and finish.
Compatibility
Inside, the design is a close copy of the 1541, using second-source 6522 VIAs and a 6502 CPU. The ROM is also a copy of Commodore’s ROM, with some instructions in the lower half of the ROM shuffled to make the code look different while behaving the same. The strings are all identical and encoded the same. The result was a lower degree of compatibility than it sounds like it should have had, and a low degree of legality. My acquaintance who bought one at Dolgin’s said it didn’t work with any commercial copy protected software he had, so he exchanged it for a real 1541 after three days.
The same friend who told me Target sold the drive told me he knew someone who received both a Blue Chip drive a game for Christmas, and the game wouldn’t work with the drive. Nothing ruins Christmas like gifts that don’t work.
Legal issues
Selling through Sears may have been what brought Blue Chip into Commodore’s legal crosshairs. Sears was already bundling Commodore computers with their own house-brand monitor and Okidata printers. Commodore couldn’t have been happy about losing the disk drive sales too.
Commodore either sued or threatened to sue the distributor. The Blue Chip drive disappeared soon after. Between the legal issues and, potentially, the compatibility issues, Sears switched back to Commodore drives. In the 1987 catalog, Sears was selling Commodore’s 1541C drive for $220. That’s a $40 premium over the Blue Chip drive, but people will generally pay more for a product that works.
The BCD/128
Blue Chip also marketed a drive called the BCD/128, the only third party clone of the 1571 disk drive. This drive also disappeared from the market after 1986, which was unfortunate given that Commodore cut production of the 1571 drive a year or so later.
The Blue Chip power supply
The biggest problem today with Blue Chip disk drives is a missing power supply. It was very easy for the power supply to get separated from the drive, and making matters worse, there is no easy, commonly available off the shelf replacement. Spectravideo used the exact same power supply pinout and wattage with its SV-318 and SV-328 computers, but those power supplies aren’t common either. I’ve seen some reports that Spectravideo was the OEM for the Blue Chip power supply.
The connector is identical to the power connector used by the Coleco Vision and the Texas Instruments TI-99/4a, but the voltages are completely different. Don’t plug one of those power supplies into a Blue Chip drive. It won’t work, and could potentially damage the drive.
The power supply uses 16 volts AC and 9 volts AC. The two outermost pins supply 16 volts AC. The two pins further inside supply 9 volts AC. Commodore’s 1541 uses exactly the same voltages internally, so if you 3D print a connector, you could build a Blue Chip power supply using a transformer salvaged from a broken 1541 for power.
Modifying the Blue Chip disk drive to use a different power supply
Another option is to modify the drive. It is possible to modify the drive to use another power supply that provides 5 and 12 volts. The Blue Chip drive has 7805 and 7812 voltage regulators on the underside of the mainboard, and those regulators have TX3 connectors plugged straight into them to route power. First, label which connector goes to the 7805 and which goes to the 7812. Next, label which wire on each connector went to pin 3 of the regulator. To find pin 3 on the 7805, use a multimeter to look for continuity from pin 16 of any of the 16-pin 74LS logic chips on the top of the board with the TX3 still plugged in. Whichever pin has continuity is pin 3. Label pin 3 with a piece of tape from the 7805’s connector as +5V. The same pin from the 7812’s connector will be +12V.
You can unplug them and feed +5V to pin 3 and ground to pin 2 of the TX3 connector you pulled from the 7805, and +12V to pin 3 and ground to pin 2 of the 7812’s TX3 from your alternate power supply. Unfortunately I don’t own a Blue Chip drive to tell you the color coding of the wires or to give a more detailed step-by-step. If this isn’t enough to tell you how to mod your drive, seek some assistance from a friend with a bit more electronics experience.
My experience with the Blue Chip disk drive
Back in the 80s, I only knew one person who owned one of these drives. His name was Sonny, the same guy who introduced me to Fast Hack’em. He didn’t like it. He called it his Cow Chip drive. Sonny could be a little weird about what he did and didn’t like, but with a name like “Blue Chip,” you expect premium quality, and the industrial design and fit and finish of the Blue Chip disk drive doesn’t exude premium.
I don’t have first hand experience with this drive, but since there is so little information available about it, I thought it was worthwhile to go ahead and blog about it. Hopefully the power supply information helps somebody.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.