Problem I always have ( Which is immensely annoying!) Is that when I format a floppy on the PC, put my programs on that disc and it works fine on the ST. however, if I save desktop, it fails to be recognised in the PC any longer. So I assume it " corrupts" FAT somehow. program I found sounded like it would fix that problem but it locks up
So wonder if anyone else has come across any other similar patches ?
Code: Select all
Information about FLOP_FIX.PRG
******************************
FLOP_FIX.PRG is a patch program for the many errors in the BIOS disk
routines in TOS2.06, 3.06, 4.01, 4.02 and 4.04 [there doesn't seem to be a
4.03].
!!!In TOS4.00 these errors still exist, but I don't have access to this
version, so could not test the patch with it.!!!
FLOP_FIX.PRG is Freeware. Anyone may copy it, as long as it is accompanied
by this file, FLOP_FIX.TXT. it may be distributed via mailboxes and
translated into other languages.
While the author has carefully checked the program, and believes it to be
correct, he does not take any responsibility whatsoever for any damage
arising in any way whatsoever, be it loss of data or whatever, from the use
of this program or this info file. The user takes the entire risk of using
or not using this patch program himself/herself.
Please read all of this file, or you may miss something very important.
Usage
*****
First place FLOP_FIX.PRG in the AUTO folder, preferably as early as
possible in the queue. It only installs itself if it finds one of the
above-mentioned TOS versions, and uses about 1K of memory. it does not
matter whether the TOS is in ROM or relocated in RAM. A message is
displayed showing whether it installed itself or not.
FLOP_FIX must be run before any programs which intercept the XBIOS-Vector
(trap#14). Otherwise there will be a message, and it will not install.
FLOP_FIX can also be run from the desktop. Multiple installation is
possible, but pointless and wasteful of memory.
I should point out that at least one program in the AUTO folder and at
least one accessory must have the fast-load bit UNSET. Ignore this at your
peril...!
Internal details
****************
FLOP_FIX attaches itself to the hdv_bpb and hdv_rw vectors with the
XBRA ID T206, replacing TOS's Floppy-Getbpb routine completely and the
Rwabs routine partially. Although FLOP_FIX tests the XBIOS vector, because
it needs it during installation, it does not change it.
The four (removed) bugs
***********************
TOS2.06/3.06/4.0x calculates a checksum from the first 6 sectors of a disk,
to make sure that disk changes are recognised. Unfortunately, in two places
no distinction is made between drives A and B. This bug is only noticeable,
if you have a second floppy disk drive, for example when: a large file is
read for display, from a write-protected disk in drive B, by the Desktop.
When the drive attempts to load the next portion of text, there is just a
READ ERROR message. A disk change has been recognised, where none took
place.
TOS2.06/3.06/4.0x can in principle work with media with only one FAT
(GEMDOS works correctly here). For this, Bit 1 of the Flags (Offset $10) in
the BIOS parameter block, must be set to 1.
The Floppy-Getbpb routine sets this bit correctly, but delivers wrong
values concerning sector placement on the disk. This bug is only noticeable
when using disks with one FAT; normal disk have two FATs.
Also, in the Rwabs routine there is an abort condition missing when
recalculating sector checksums for sectors 0 to 5. If you write more
than one sector using Rwabs with a start sector of 0 to 5, it is
possible that VDI information about text style, text size and font can
be overwritten. This produces a rather unusual Desktop. Because of
the first-mentioned bug, this bug only occurrs with disks with at least 13
sectors per track.
History
*******
There is a program PATCHX06.PRG by me, which is only designed for TOS2.06
and TOS3.06. FLOP_FIX has no functional changes, but now supports TOS4.0x.
ED Disks
********
FLOP_FIX.PRG allows you to work properly with ED disks (2.88MByte),
with either 12Bit-FAT (such a disk has at least 2 sectors per cluster)
or 16Bit-FAT (such a disk has 1 sector per cluster). The differentiation
between the two FAT sizes is anlogous to MS-DOS, using the number of data
clusters. Up to and including 4078 data clusters it is assumed to be a
12Bit-FAT. Above 4078 data clusters a 16Bit-FAT is assumed.
Maths hint: The changeover does not occur at >4096 clusters, since some
cluster numbers are used internally for marking purposes ($FF0-$FFF) or are
not usable ($000, $001).
The Author
**********
I am a student and use my computer whilst in the middle of studying.
I hope that I don't have to develop this program further in the future,
since Atari have removed the bugs in the unofficial beta test TOS4.92.
Here is my address. If you absolutely need my telephone number, you can
find it in the [German!] phone book. However if someone phones
outside of the hours from 07.00 to 21.00, it will not help to put me in a
particularly good mood (you have been warned). I would at this stage like
to thank all those who have helped with the continued development of
this patch program.
Berlin, 28.08.1992
Harun Scheutzow
Dresdener Straže 83
D-10179 Berlin
or by e-mail
Mausnet: Harun Scheutzow @B
Internet: Harun_Scheutzow@B.maus.de