🚀 go-pugleaf

In article <3525@druhi.ATT.COM> dlm@druhi.ATT.COM (Dan Moore) writes:
> 	Are you sure that the old ROMs can't read the last two clusters
> on the disk?

I didn't say that.  I said we couldn't fix the bug for compatibility
reasons.

You are exactly right: the old ROMs can read the last two clusters, just
fine; they can even write to them if a file is already allocated there
and you are overwriting that part of the file.  What they can't do is
extend a file into that part of the disk, and they always report
that space as used when you use the Dfree call.

Imagine the following setup:

A company produces an application on new ROMs, and the application
plus its support files EXACTLY FILLS a new-ROM disk.  By chance, the
DESKTOP.INF file which the company provides on that disk is in the
very last cluster of the disk.  (Remember, that's the last cluster
of a NEW ROM disk.)

The poor, hapless user with old ROMs dutifully copies this master disk
to a working disk, then changes his palette using the control panel and
chooses "save desktop." What happens? The desktop does an Fcreate, which
deletes the old DESKTOP.INF file.  The Fcreate succeeds, but the Fwrite
doesn't, because there's no space on the disk! (As far as the old ROMs
are concerned, there is actually -1K used!) Poor user. 

This scenario isn't really stretching too far, and there are lots of
variations on the theme.  It creates a situation which we are willing to
pay 2K per floppy to avoid.  2K is, after all, only 0.55% of a
single-sided disk, 0.27% of a double-sided disk, and infintessimal on a
hard disk.  Yes, it was a bug in the original GEMDOS, and yes, we know
how to fix it, but it would be problematical to do so. 

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt