'Fat tracks in emulation'
Author:Rixa (guest: search)
Date: Fri, Apr 10th, 2009 @ 04:22 ( . )

I've been playing with an 1541 Ultimate and images of my originals. Fat tracks seem to be a bit of a problem with it but not VICE. Even when helped a bit, I discovered something puzzling that happens most of the time with VICE too.

M.U.L.E. is listed in the database as having a fat track on 34/35. I made the image now used with mnib36 or nibtools some years ago, and it boots up in VICE. For it to boot in the 1541u I needed to tweak it manually so that tracks 34, 34.5 and 35 all point to the same data (this is how a fat track is supposed to look like, right?) No other half-tracks are included in the image and it wouldn't work without this one, so I'm guessing that with the 1541u half-tracks are empty unless provided. I wonder what VICE does with unprovided half-tracks?

Anyways, I noticed that the game loads twice with both, at least most of the time. When it works correctly in VICE, I think it first loads the loader from track 17, then the game from tracks 1 to 7. Then it moves to track 34 and from there to 35 and back, spending several seconds each step, including the half-track in between. Then the game starts.

When it doesn't work just correctly, it doesn't stop here. It moves back to 17.5, then 1.5, and all the way to 7.5 like before but half a track higher. The protection track then loads the same, except it jumps straight to 34.5, skipping the initial 34. THEN the game starts. It also loads twice on the 1541u, but if I'm right about the half-tracks being empty, it can't be loading from them..

Any insight on what could be working against me here? Is there something I've overlooked image-wise or is it just a case of imprecise emulation? I wonder why it doesn't work on the first go but does on the second.


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Replies:
--* Fat tracks in emulation
4/10/2009 @ 07:56--Pete Rittwage
4/11/2009 @ 01:28----Rixa
4/12/2009 @ 13:29----Lord Crass
4/12/2009 @ 20:52------Pete Rittwage
4/13/2009 @ 01:50--------Lord Crass
4/13/2009 @ 09:28----------Pete Rittwage
4/13/2009 @ 13:47------------Womo
11/16/2010 @ 18:41--------------J Achernar

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