Adding A Second Drive To A Forgotten Commodore

Commodore would never release a laptop, or really much of anything resembling the chunky luggable portable computers of the 1980s. This doesn’t mean a ‘Commodore LCD’ wasn’t designed – it’s sitting in [Bil Herd]’s basement. Of the entire Commodore lineup, the only computer that could remotely be called ‘portable’ is the SX-64, the ‘executive’ version that came with a built-in 5″ monitor, the usual C64 circuitry, one floppy drive, and an empty hole that could obviously hold a second floppy drive. Something must be done about that missing floppy drive, and it only took thirty years for someone to do something about it.

While the conversion requires mucking around in an already tight enclosure, the parts for this conversion are readily available thanks to a few people trying to repair an SX-64, giving up, and parting the whole thing out on eBay. These parts include the 1541 controller relabeled as the ‘FDD’ board in the SX-64, and of course the floppy drive itself. With the right teardown guide, putting the new drive in this old computer isn’t that hard; just remember to cut a jumper to assign the new drive a number other than 8.

The missing floppy drive of the SX-64 is what happens when marketing is put in charge of engineering. There were a few of these dual drive Commodore luggables back in ’83, and we have the computer magazine clippings to prove it. The official story is the power supply wasn’t beefy enough to handle the second drive. This mod, though, seems to work well enough, albeit with a distinct lack of somewhere to store a few floppies.

Find yourself getting sentimental while reading about this great hardware? Keep those feelings going by listening to [Bil] recount some stories from his time at Commodore.

18 thoughts on “Adding A Second Drive To A Forgotten Commodore

  1. I restored an SX-64 last summer, replaced VIC and some 74xx logic on clock daughterboard plus some 3D printing for those keyboard clips. the dual drive mod is cool, but an sd card reader on device 9 is a little more practical. has anyone tried the 1541 ultimate on the SX? I assume it’ll work but they are a little expensive.

  2. Floppy !? 720k? 1.44 MB? What kind of talk is this in 2015 when GB of SD RAM go for small change! I had one of these SX-64 in the mid 1980s & found them (even for the hardware of the era) a mixed bag. The SX-64 package was VERY trendy & it’s audio astounding, but the the video display was not only small but slow & ‘low res”. I recall we took to an external monitor for anything serious & thankfully sold it to someone after something sexy before depreciation became too savage …

          1. spreadsheets were the killer app at the time for these machines, maybe a light database. the only thing this floppy speed was practical for was multiload games.

            that said a generation of kids cut their teeth on commodores and sinclairs, there was a huge knowledge gap emerged a generation later when computer literacy and training switched from code to office applications and web browsing. The idea of modelling a real world problem in code and solving it was lost, to the idea of just paying for a packaged app to do it for you.

            This is a problem the makers of the raspberry pi identified and sought to address.

  3. If I had one I’d put in a Famiclone so you can insert NES cartridges into the hole for the second drive and make the monitor switch to that signal as well as switching the joysticks (Famiclones use DB9 like C64 only they don’t output the signals, so you need to put in a 4023 (or was it 4027?) to convert the joystick signals).
    This would put the two best 8-bit systems in the world into one luggable enclosure. Nintendore 64…

    1. Years ago I saw someone’s project where they installed a Mini-ITX motherboard into one of those, but kept the 5″ NTSC monitor connected. A slot-load optical drive went in behind the floppy bezel, too. The entire thing was completely stealth, so they could minimize a C64 emulator and blow minds.

  4. I bought one of these when I was in college. Took a 1541 and cut the board in half and fit it all in. If you look at the board on a stock 1541 you can see a line down the middle separating the analog side from the logic side, it only took a few jumper wires to connect the two. I did the piggyback stereo SID as well. This would have been somewhere in 1992-1993, wish I had taken pictures then.

    After a few hours of use the drive would start having issues due to heat

  5. *ALMOST* got to get my hands on one of these through a boss’s friend who may or may not still have had hers. I was trying not to let slip that they’re quite expensive on eBay, lol. Big fan of my old Commodore, just got my C-64C up and running. Also just acquired a Commodore N60 Aeronautical Navigation Calculator from the 70s as a toy to combine my love of Commodore and flying.

  6. I saw one of those sitting in a surplus store once, but since I was sans fundage I thought, “I’ll come back and get it later.” Needless to say when I got back it was gone.

  7. Made mine a DX back in 1986. Works great.used 2 SX-64 systems to make one DX. Still have the SX-64 without the drive an controller. Works find. Just no drive. Was picking up the SX-64 for about $75 from Commodore. This is when they were dumping/selling all the ones that were returned under warranty.

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