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Raspberry Pi acting as C64 disk drive w/out microcontroller

FozzTexx

FozzTexx

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I put together a video of my Raspberry Pi acting as a Commodore 64 disk drive. It works without using an external microcontroller, the IEC bus is interfaced directly to the GPIO pins on the Raspberry Pi.

This essentially turns a Raspberry Pi into a NAS or SD card reader for a Commodore 64. No more sneakernet or swapping floppies!


There's still more work to do, like d64 support, finding a way to have the C64 issue commands to change directories or switch disks. It's all open source and is available on github.
 
Wow. Very cool :) I'd love to see more vintage computing features that a Pi could do. That could seriously make some sales for their product if it can start emulating drives for different vintage systems! I still have yet to make the leap to their or any other usb powered micro/stick computer (Computer On a Stick? COaS?).. not sure what the kids are calling it these days ;-)
 
You know, it probably wouldn't be particularly difficult to do an IEEE-488 interface for the PET using this technique. I suspect it might even be easier provided there are enough GPIO ports available. I've never actually done any hardware hacking with my Pi so I just don't know offhand.

FozzTexx said:
I put together a video of my Raspberry Pi acting as a Commodore 64 disk drive. It works without using an external microcontroller, the IEC bus is interfaced directly to the GPIO pins on the Raspberry Pi.

This essentially turns a Raspberry Pi into a NAS or SD card reader for a Commodore 64. No more sneakernet or swapping floppies!


There's still more work to do, like d64 support, finding a way to have the C64 issue commands to change directories or switch disks. It's all open source and is available on github.
Click to expand...
 
I was recently looking at the sd2iec and others trying to figure out what had the most following for a virtual drive. Between products that don't seem to be created anymore and some hefty price tags, if this could gain some ground it could potentially emulate other busses as well not just commodore (although Commodore would be great anyway). May take a while, not sure how active the coding is (I do see some updates from 2 days ago though) so you'd at least have a peripheral you can play with other stuff on while waiting for the kinks to get worked out :)
 
I suppose one drawback with using a Pi for this is the need for an additional power source. I read that the model A draws 300 mA and the model B with some peripherals might draw 700 mA. I'm unsure how much the 5V on the cassette or user port is rated to output, the joystick ports can output in the range of 100 mA but the ports on the back side might have a little more juice.

Besides, I don't find the various sd2iec solutions that expensive. What is interesting though is if a Pi has enough CPU power to fully emulate a 1541 floppy drive including its 6502 CPU, 6522 VIAs, ROM, RAM. If that is the case, you could get a serious contender to the 1541 Ultimate series. If you also can get a C64 cartridge connection to the Pi, it'd be even closer.

Edit: Aha, all 5V outputs on a C64 are on the same circuit, with a total of max 100 mA. There goes the idea to hack a micro USB cable to power the Pi. The PSU delivers 1.5 - 1.7A on the 5V line, but I suppose it would be a cheap try to hack that cable, better to use an external power source. The dedicated SD devices appear to draw some 20-30 mA, which is why they safely can be powered from the computer itself.
 
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For reference, the new VIC-VODER for the VIC-20/C64/C128, which has a Raspberry PI within its casing, draws 515 mA from the C64's user port. VIC-VODER developer Rick Melick recommends a heavy-duty C64 power supply when the VIC-VODER is used with a C64.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
 
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