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There's some nice background here: https://www.lemon64.com/forum/viewtopic.php?t=52439 https://www.lemon64.com/forum/viewtopic.php?t=52439 The Ultimate 1541 ta
by EvanAnderson 5y ago
There's some nice background here: https://www.lemon64.com/forum/viewtopic.php?t=52439 https://www.lemon64.com/forum/viewtopic.php?t=52439
The Ultimate 1541 talk is also great: https://www.youtube.com/watch?v=_1jXExwse08 https://www.youtube.com/watch?v=_1jXExwse08
The 1541 maintained compatibility with the VIC. The VIC had very slow firmware routines to communicate with its 1540 disk drive because a shift register in the 6522 VIA chip didn't work properly.
The C64 had an improved VIA with a working shift register. The 1541 attached to a C64 was going to be much faster than the 1540 and the VIC. A board rework in the 1541, however, removed a trace needed for the high-speed operation, so the 1541 and a C64 ended up being no faster than a 1540 and a VIC (and actually slower because the VIC-II in the C64 needed to take control of the bus periodically introducing jitter in the communications).
- EvanAnderson 5y agoI've been trying to find a reference to the board rework removing the high speed serial capability. I heard about it originally in a video or podcast and I'm going to do some digging to find that. To correct the record, though, the board rework story references the C64 motherboard and not the 1541 board.
- vinkelhake 5y agoAlso worth checking out: http://www.quiss.org/freespin/ http://www.quiss.org/freespin/ This is a demo running entirely on the 1541 using a hacked together connector from the drive's serial out to a monitor. Audio is generated using the stepper motor.
- kingcharles 5y agoo_O What's amazing is that it's actually a neat demo with cool music. And the only additional hardware it uses is ONE RESISTOR.
- Zenst 5y agowow, now that is some serious hacking and mind-blowing. Probably one of the best abuses of hardware I've seen for a while.