The Ultimate Commodore 1541 Disk Drive Talk [video] | Hacker News Reader

The Ultimate Commodore 1541 Disk Drive Talk [video]

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96 pointsAudiophilip16 comments

I was lucky enough to see this talk in person at the Vintage Computer Festival West this year.

One of the absolute highlights (timestamp https://youtu.be/_1jXExwse08?t=1903) was the incredible work on a custom disk loader that increased the throughput from 400 bytes/s to 7.5 kB/s! A writeup of that optimisation work, which was only published in 2013, can be found here: https://www.linusakesson.net/programming/gcr-decoding/index....

The same person also wrote "The TTY Demystified" also a very good read: https://www.linusakesson.net/programming/tty/index.php

"In order to shave off a cycle from every instruction that modifies another one, the entire loop will be placed in the zero-page." Oh wow.

If you like that kind of stuff, here's the 256 bytes (!) C64 intro "A mind is born" and its technical explanation... It's using that same zero-page trick:

https://linusakesson.net/scene/a-mind-is-born

I have no words... These coders are amazing!

> increased the throughput from 400 bytes/s to 7.5 kB/s

Since then someone has come up with yet another custom disk loader that's more than twice as fast as that one!

https://csdb.dk/release/?id=197710

It's incredible that people are still pushing the limits of the stock C64 system these days...

>It's incredible that people are still pushing the limits of the stock C64 system these days...

It's staggering to think that such a thing is possible on the stock hardware, just as it is staggering to consider that 1024 colors on a stock IBM PC with CGA is possible as the 8088 MHz demo has proven. What would have happened if an IBM engineer in 1981, or Commodore KERNAL developer in 1982, had had the necessary insights to come up with such innovations? CGA and the early IBM PC's reputations as a poor computer for games would not have come to pass. The C64 and 1541 would have been viable for things other than games.

Of course, the PC standard took over the world despite CGA's four garish colors. Of course, the 64 was the dominant home computer of the 1980s regardless of the need for a third-party fast loader. But one can't help but wonder what more could have been done.

I wrote one of the early fastload cartridges for the 1541 (Epyx had the famous one, but mine also did a fast format, and drive to drive backup across two 1541s) and am looking forward to going down memory lane with this talk! Thanks for the share!

I had the Epyx one, but I never realized there were others.

Mine was the GT4 cartridge, distributed by Pro-Line Software, the same folks who distributed WordPro 64, WordPro for the Vic-20 which I did the port for and likely some versions for the PET as well though that was probably Pro-Micro software IIRC.

Looking forward to watching this. His previous talks, such as the Ultimate Commodore 64 Talk, have been comprehensive, clear, while being very concise on each bit of info.

Does a high quality version of the Ultimate C64 Talk exist somewhere? I only see fairly low bitrate versions of it. (The embed on Michael's website is dancing postage stamp-sized.)

Not exactly what you're asking for, but https://www.youtube.com/watch?v=ZsRRCnque2E while being 480p and rather noisy, was very sufficient for me to watch and enjoy the talk back in the day. The presented material does not suffer much on the relatively low resolution.

I'm not sure there is one. There are some mirrors[0] that have a copy of the original recording[1], but apparently still very low-res.

[0]: https://events.ccc.de/congress/2008/wiki/Conference_Recordin...

[1]: http://ftp-stud.hs-esslingen.de/Mirrors/CCC/25C3/video_h264_...

I'm only 20 minutes in, but I can already tell you that you won't be disappointed. I feel like after just about a third of the video I already fully understand the physical and logical disk format. Like the previous videos, it's chock full of dense information presented with very clear visualization.

I remember, as a kid, playing copy protected games at night and hoping my dad didn't wake up mad at me because of all the CLACK CLACK CLACK CLACKing that the drive head was doing as the protection scheme was slamming it all the way to one side to read some bit of data.

Good times, man.

I was astonished to learn that it takes another 6502 to power the 1541 drive. Kinda neat if you think about it, and I believe someone has succeeded in using it as a 2nd processor, much like the famed 6502 coprocessor tube on the Acorn machines. Those days were great.

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