Re: Order of sectors on a track

Re: Order of sectors on a track

Date: Thu, 21 May 2009 16:02:01 -0400 (EDT)
Message-ID: <>
> Hallo allemaal,
> For my 1541IDE project the idea was first to find out what the order of
> sectors on the tracks were. To my surprise that was 0, 1, 2, 3, 4 etc. My
> first reaction: but what about interleave ??? Then I realised that
> interleave is something that is done by the software, not the hardware.
> My question: can I trust that all sectors are numbered in this order on a
> track?
> If that is the case I can discard the routine to determine the right
> order.
> OTOH I realise there could be disks where someone deliberatly changed the
> order: in that case, what is wise?
> My routine to find the headers is mainly a copy of the "read header"
> routine found at $F3B1. But I was only able to run the routine by
> disabling
> IRQ. I have to because if no job is found, the "Byte ready" line is
> disabled and I cannot detect the SYNC marks anymore.
> I'm convinced that I can copy the whole disk W/O depending on interrupts.
> But there is a possibility I overlooked something. So comment is welcome!

Hi Ruud,

99% of disks have them in sequential order.  There are a few anomalies,
but it is usually not using the CBM loader in those cases.

I do wonder why that would matter, though.  You are decoding them and
storing them on the hard drive that isn't GCR, so this should not matter. 
Much like a D64, it shouldn't know or care about sector headers.

Pete Rittwage
C64 Preservation Project

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Received on 2009-05-21 23:17:51

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