Technical information

© Jean Louis-Guérin – V1.2a – September 2014 Page 35 / 69
Chapter 6. Atari Utilities
6.1 BigDOS
BigDOS freeware Copyright© 1995 by Rainer Seitel
BigDOS is an ISO 9293 file system that replaces the GEMDOS of TOS.
6.1.1 Features
 GEMDOS / ISO 9293:1987 / MS-DOS file system
 32 Drives: A..Z 1..6 or A..Z [\]^_`
 Up to 65518 cluster.
 1 to 64 sectors per cluster.
 More than 65535 sectors and therefore every MS-DOS partition possible. That means also more
than 32 MB.
 1 or 2 FAT.
 The legal characters are - configurable for each drive - restricted for GEMDOS, d-characters as in
ISO 9293 resp. ISO 9660 or MS-DOS. You know in advance, that a MS-DOS computer or
restrictive CD writing software can read all files. With setter.ttp from the HSModem archive, or the
GEM version of Setter, from Markus Kohm, this can be permanently set in BigDOS.
 The disk label will also be written to an MS-DOS boot sector.
 Works with or without MiNT.
 BigDOS tries to lock removable cartridges using XHDI, if there were open files on it.
 For TOS 1.04 and 1.06 no POOLFIX3.PRG, PFIX_CB.PRG or POOLFX92.PRG is needed.
 For TOS 4 no F030HFIX.PRG is needed.
 94 standards handles for open files, instead of 75.
 Cookies ¯DATE® and ¯TIME® as in DTCOOKIE and LED-Panel.
 Shows names of the loaded accessories.
6.1.2 Installing BigDOS
BigDOS.PRG (for the Falcon at present BigDOS-F.PRG) should be the first program in your AUTO
folder after the boot selector. In any case before every program in the GEMDOS trap which not use
XBRA. BigDOS.PRG installs itself at the end of the XBRA chain. You can use the Autosort program to
reorder the programs in your AUTO folder.
For MS-DOS partitions bigger than 32 MB, you also need a hard disk driver which can handle big MS-
DOS partitions (type 6) and allows access to more than 65535 sectors via Rwabs(). This should be a
driver with XHDI 1.20, because BigDOS tries to change the DOS limits via XHDOSLimits(). This
function could be checked with XHDItest.ttp.
6.1.3 BigDOS Sundries
DOSMODE.TOS shows and alters the legal characters for filenames on each drive:
 GEMDOS: A..Z0..9!#$%&'()-@^_`{}~"+,;<=>[]| and capital umlauts
 ISO: A..Z0..9_
 MS-DOS: A..Z0..9!#$%&'()-@^_`{}~ and capital umlauts
With setter.ttp from the HSModem archive, or the GEM version of Setter, from Markus Kohm, this can
be permanently set in BigDOS.
XHDITEST.TTP shows for all or a given drive letter the partition size, bad values in the BPB, name
and XHDI version of the hard disk driver and tests the DOS-limits function:
 :-( not available
 :-/ available, but could not change the limits
 :-) available and could change the limits
BigDOS, NVDI and the Screenblaster driver doesn't work together. Omit one of them.
There are several Programs that initialize the file system not correct. By the first access or after a
media change, an error message is printed on the screen. If you type J or Y for yes the correct value
will be written on disk. Contact the responsible programmer and tell him about the bug. (Now you can
switch off this check with Setter.)
 BigDOS: FAT start of ?: shall be $F?, $FF, $FF [$FF]! Write? [YN]
 BigDOS: Media byte in boot sector of ?: is $??, shall be $F?! Write? [YN]