[Coco] Mystery "FDC (EAGLE FORMAT)" Schematic on MaltedMedia FTP

[Frank Swygert]

Date: Sun, 8 Feb 2015 16:03:32 -0600
From: Chad H<chadbh74 at hotmail.com>

I gues with it being a deviation away from the standard controllers it would not be the best choice for trying to reproduce floppy controllers based around this chip.  I have been off and on investigating if such controllers could be reproduced for a reasonable cost.  I know I can get the WD1773 chips but they are a bit costly.  The MD8877A chips like was used in some of the FD-500 controllers is cheap.  I also found scans of what appears to be Tandy's own schematics for some controllers but they appear to be hand-written and somewhat difficult to make out.  Also, not every component is clearly identified.

I now have a total of 3 Floppy controllers, 2 FD-502s and 1 FD-500. I'm good with this for now but with them seemingly becoming more scarce and most of them with the non-gold contacts suffering from increased oxidation I thought it would be nice to reproduce some with the nice gold ENIG contact finish we have been seeing on some of these new projects.  We could even take the opportunity to upgrade the EPROM IC to support up to 27512's or maybe even something like the 256K EEPROM I'm working on that may be programmable from the CoCo itself.

Of course, I have no idea how much interest there would be out there in this sort of thing as a lot of people seem to have abandoned floppies altogether.  If I invested the time and money trying to cobble up some prototypes it's very possible it may just be a one on one off deal.

- Chad

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The community problem, and the main reason people seem to be abandoning their floppies, is more the drives themselves than controllers. Second would be finding good media to put in them. The mechanical drives are wearing out and the working ones are becoming more collectors items than daily use items. The old media is deteriorating and new is getting hard to find and expensive since they have all but disappeared in mainstream computing. Computers made in the last 5-6 years don't come with a floppy drive, they usually have a card reader instead. That's why the SDC cartridge and tools to transfer from a PC to a CoCo format have started to become a standard -- that and DriveWire. DW has become popular because most of us already have a PC or two, and usually have an older one that can be used exclusively as a DW server. The CoCo doesn't have much computing power compared to even the single core Raspberry Pi, so having something to help out on file transfers and printing (not to mention printers that work with the CoCo are also hard to find) is a great help to keeping the original computer itself running. It's getting more and more practical to use an emulator on a PC to keep a bit of the CoCo experience alive than use the old hardware. I know that's "sacriligous" to many here, but it's the truth. Keep the old hardware for nostalgia as collector's items, but for playing/working use a PC emulator. I know it's not the same, but...  Setting up an older laptop of small form factor computer with an emulator is a good idea to use in place of a CoCo today. Just a fact that the old stuff is wearing out and becoming harder to find. I see the same thing with my old Rambler cars. Many of us who like to drive them are repowering with modern drivetrains and saving the old iron for restorers. It's not the same experience, but better than getting far from home and have something simple like ignition points or a water pump go out. Good points are hard to find, though Rambler used common GM or Ford electrics (no, they didn't buy everything from other manufacturers, but did buy a FEW parts from others... why reinvent the wheel if you could buy cheaper than build your own?). Water pumps and such for an engine that hasn't been produced since 1965 (the old Rambler six) is a special order item. Want an expensive tow bill or to sit 3-4 days while you wait for a part to come in? Still have that problem using the old body and suspension to a degree, but those parts are less likely to fail without warning.