Re: Commodore 15 Second disk format routine disassembled

From: André Fachat <afachat_at_gmx.de>
Date: Fri, 19 Jun 2026 15:25:10 +0200
Message-ID: <19ee00e8af0.2874.b4d1f2b66006003a6acd9b1a7b71c3b1_at_gmx.de>
Am 19. Juni 2026 15:10:17 schrieb gsteemso <48bitsorbust_at_gmail.com>:

> Hi,
>
>> On Jun 19, 2026, at 5:59 AM, groepaz <groepaz_at_gmx.net> wrote:
>>
>> Am Freitag, 19. Juni 2026, 14:45:10 Mitteleuropäische Sommerzeit schrieb
>> gsteemso:
>>
>>> ...maybe, if you could get the controller to squirt the bits out fast enough
>>> (you can't), or if you could read them back fast enough (you really can't),
>>
>> You really can. It works exactly the same no matter the track.
>>
>>> or if it didn't exceed the media's design limits on flux transitions per
>>> unit length (it does).
>>
>> This is really the only problem - however its not THAT bad really.
>>
>>> Working in simulation means nothing to actual physics.
>>
>> After having developed stuff for the catweasel (which involved hundreds of
>> different physical formats) i dare to say i know a little bit about the
>> physics involved :)
>>
>> (There have been commercial copy protections doing this, even on tracks > 35)
>
> OK, I'll happily believe you if I can see it in action...  That said, I 
> will have to remain skeptical until I see it survive (a) drives that vary 
> slightly amongst themselves in spindle speed and (b) mediocre media quality.
>
> G.
Commodore drives are very good at compensating spindle speed. They 
synchronize the bit counter on every 1-bit. Not like other systems

André
Received on 2026-06-19 15:01:02

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