Re: ADT questions

[pausch@saaf.se (Paul Schlyter)]

In article <8OSdnbv3NeBKE3nYnZ2dnUVZ_uDinZ2d@comcast.com>,
Michael J. Mahon <mjmahon@aol.com> wrote:

> KPR wrote:
>> David dos or pronto dos ( one of them ) supported 40 tracks.. then
>> there was the trick to format a data disk and recoup the first 3
>> tracks by not putting a dos image on it..  40 Tracks * 16 Sectors per
>> track = 640 sectors - boot sector and catalog track ( 17 sectors ) =
>> 623 Sectors = 155.75k.. that sure beat the 128k of usable space per
>> dos formattted disk..
> 
> And the only cost was the loss of interchangeability with the rest
> of the world...  ;-)
> 
> "Being standard is better than being better."

I guess that depends on how much better "better" is .....

I carried the situation above to a greater extreme: instead of
settling for 40-track single-sided disks I went all the way to
80-track double-sided disks.  This of course required new disk drives,
an adapter card between the disk drive and the Apple II disk
controller.  And also a new control line, for selecting which one of
the two sides of the disk should be accessed - I picked that line from
the game connector.

Now, I really had a non-standard Apple II system -- few Apple II's
could handle 80-track disks or double sided disks.  I wasn't all
alone though: a friend of mine who also had an Apple II did the
same modification.  I also kept a 40-track single-sided drive for
compatibility with the rest of the world.

The advantage was obvious though: much bigger disk space.  Instead of
140K disks I now had 640K disks.  The disk size was actually too big
for Apple DOS to handle, so there I let one 80-track double-sided disk
become two DOS volumes, distinguished by drive numbers: the back side
of drive 1 became drive 3, and the back side of drive 2 became drive
4.

But with Apple Pascal and Apple CP/M there was no such problem, since
these OS'es could easily handle 640 KByte disk volumes.  I hardly ever
used Apple Pascal though - the few Pascal programs I had I transferred
to CP/M and there I ran them on Turbo Pascal instead.

Some 15 years later the Apple had become obsolete, and I wanted to
transfer all my old files to more modern computers.  I started with my
CP/M files, where the transfer was quite straight-forward: I
transferred it all, file-by-file, using the Kermit file transfer
protocol - the disk volume size then mattered little.

But Apple DOS files made little sense outside the Apple II environment,
so there I resorted to using ADT to transfer disk images.  Which of
course meant I first had to copy my Apple DOS fles residing on high
capacity floppies to standard 35-track Apple II floppies first, and
*then* I could transfer the disk image of that floppy using ADT.
I used one and the same floppy for this, and that floppy was filled
with new files a lot of times.  I reformatted it in between to
maintain "fresh" disk contents (i.e. no remnants of old deleted
files on unallocated sectors).


"Standards are a good thing - there are so many standards to choose
among".... :-)


> -michael
> 
> NadaNet networking for Apple II computers!
> Home page:  http://members.aol.com/MJMahon/
> 
> "The wastebasket is our most important design
> tool--and it's seriously underused."

-- 
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