RE: Order of sectors on a track

RE: Order of sectors on a track

Date: Mon, 25 May 2009 08:11:49 +0200
Message-ID: <>
Hallo allemaal, 

What should have been a lovely Sunday turned into a day full of hard
labour: for the first time in twenty years something infected my laptop
:( To be short, yesterday was a waisted day.

Hallo Patryk,

> you just get the next available sector and check whether you
> need this one 

The problem is that the header is GCRed as well. And decoding the header
after having read it takes too much time I already found out: the first
SYNC I was able to catch was of the next header ie. I missed the data

As waiting for the _known_ 4th sector worked out fine for track 25..36,
I decided to use this for the lower tracks as well. But the moment I
wanted to program my EEPROM, that virus, worm or whatever spoiled the
fun. This mechanism also has another advantage: If the sector order
isn't as expected, I still can be sure the right one is read. 

> and you don't have to wait for sec 0, etc..

One trick I still have in my sleeve is reading and decoding a header and
using the next header as starting point. This will save me 35 * 1/6 / 2
= 3 seconds in avarage.

> but the biggest gain is in GCR decoding 

I need 24.3 sec. to read the sectors. Which means I need 10 secs. for
changing tracks and finding sector 0. Make that 7 if the above trick
works. I now use 4 sectors for handling 1 sector = reading, decoding and
saving it to HD. Decoding and saving it to the HD in 1 sector seems
impossible to me. Doing everything in 3 sectors means 35 * 1/6 * 3 =
17.5. Plus the 7 seconds mentioned above gives 24.5. So I wonder how you
manage go as fast as 21.x sec. 
Hmm, I think I know: you mentioned speedloaders. They normally only read
the data from disk, they don't store it on another device as well as I

Hallo Spiro,

> This is what I described when I told about how the warp routines
> in OpenCBM and Star Commander work. But it seems I was ignored. ;)

No, you weren't ignored, but I cannot use the Warp routines because I
cannot use the GCRed data.
Regarding the 1571 routines, at this moment I cannot use them as I don't
know enough of how to use them; the sources I have lack a bit of comment
on this subject.

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Received on 2009-05-25 09:19:29

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