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Old 04 January 2018, 17:00   #1
Giants
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Amiga Floppy Disk layout

Hi !

In france they are a old edition book from Micro Application : LA BIBLE DE L'AMIGA
They're exist 2 Tome (Tome1 and so, Tome2 that is a the same version with correction of tome1)

in Tome 1 I have this picture :



I think there is an error.
The first tracks (so 0), start on Side0 (which is upper, which is the FACE1 on the picture) and, on Amigados have 11 sectors/side

If we use the sector information, the eleventh (yes because we start from 00->10 = 11 blocs) sector/bloc is the first sector on other side


So for me, it's a mistake in this picture...

Blocs 11-21 must be on Face2 on this picture
and
Blocs 00-10 must be on Face1 on this picture.

If anybody confirm this ?

Last edited by prowler; 05 January 2018 at 01:55. Reason: Embedded the image for clarity.
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Old 04 January 2018, 18:34   #2
phx
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No. Block 0 (the boot block) starts on the lower side of the disk. Block 11 (first sector of track 1) is on the upper side.
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Old 04 January 2018, 18:49   #3
Giants
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Are you sure about this ?

Because when we start a doscopy with X-copy, it start first whith 'UPPER SIDE',
So x-copy don't start in block 0?
Strange isn't ?

With MKIII, a RT 0 2 50000 , go in your way, Start reading Lower side and after Upper.

Why X-copy start from upper side ?
And burstnibler start from lower side... -_-'

And, i think they are not really 'standard' name for Head (0, 1 sometimes even 2).

Best is to talk about 'upper' and 'lower'

Last edited by Giants; 04 January 2018 at 19:01.
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Old 05 January 2018, 01:29   #4
phx
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I'm pretty sure about it, because I wrote a trackloader which sets CIA-B port B bit 2 (DSKSIDE) to select the lower head, whenever I access an even track. And it reads the data I expect it to read.

According to the Hardware Reference Manual DSKSIDE=0 means upper head and DSKSIDE=1 means lower head.
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Old 05 January 2018, 11:13   #5
Giants
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#Block 0 (the boot block) starts on the lower side of the disk.
#...DSKSIDE=0 means upper head and DSKSIDE=1 means lower head.

So Start begin from DSKSIDE=1 !?
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Old 05 January 2018, 14:02   #6
phx
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Quote:
Originally Posted by Giants View Post
So Start begin from DSKSIDE=1 !?
Yes. Which is the lower side. So your graphic is correct.
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Old 05 January 2018, 18:30   #7
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OK, so This =>


Last edited by Giants; 05 January 2018 at 21:42. Reason: Html error
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Old 27 May 2018, 01:29   #8
ross
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Warning.

I arrived quite randomly on this page (I was looking for a utility for MFM conversion ..) and I noticed that former picture
can be misleading for those that approach the Amiga floppy system.

In the Hardware Reference Manual, as already specified by phx, it's clearly indicated that DSKSIDE*=zero implies the upper head.
But this, like many other CIA's signals, is negated.

So actually to select lower side you need to write 1 to DSKSIDE*.
Sectors count up from cylinder 0 side 0 sector 0 (outer disk position, lower side).
Alternatively Amiga uses tracks (where track 0 is [cyl.side]0.0, 1 is 0.1, 2 is 1.0, 3 is 1.1, 4 is 2.0 and so on).

The correct version:

Code:
Blocks 11-21 (track 1)   [Upper head] Side 1 | DSKSIDE*=0
                         --------------------------------    (cylinder 0)
Blocks 00-10 (track 0)   [Lower head] Side 0 | DSKSIDE*=1

Last edited by ross; 27 May 2018 at 02:01. Reason: improved my beautiful chart :P
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Old 03 August 2018, 14:12   #9
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Exact !
Thks
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