IDEFAT16.TXT
 
 
 
Info Version 18/06/2000
File: IDEFAT16.TXT - 18/06/2000
Subject: FAT16 driver for Sunrise MSX ATA/IDE interface
By: Jon De Schrijder (jon@msx.ch)
If you want to use FAT16, read this text carefully !

On a normal MSX system, only the FAT12 filesystem is supported. With that filesystem, the maximum size of a drive(letter) is 32MB. When using a FAT16 filesystem, a drive can be approx. 2GB. To support FAT16 on the MSX, you need to install a FAT16 driver.

This text contains some additional information about the FAT16 driver made by Okei. The latest version of her driver (ver 0.07b) supports both MegaSCSI and IDE. It is still in a beta stage because Okei expects some problems with MegaSCSI. For IDE, everything seems to work perfect.

To use the FAT16 driver with IDE, you need IDE bios version 2.00 or higher.

The FAT16 driver is installed simply by running the FAT16.COM program. This program patches the DOS kernel in order to support the reading and writing of FAT16 formatted partitions. If 1 primary mapper RAM segment is available, it will be allocated by the FAT16 driver to perform caching.

This driver remains active until you reset your MSX or until you uninstall the driver by running FAT16 with /R option. Uninstalling can be useful to free the RAM segment that was used for caching.

As long as the driver isn't installed, the drive(letter) to which a FAT16 partition is assigned, WILL NOT WORK PROPERLY. WRITING DATA TO THE FAT16 PARTITION IF THE FAT16 DRIVER IS NOT INSTALLED, WILL CERTAINLY CAUSE DATA CORRUPTION ON THE FAT16 PARTITION!

When the driver is installed, all FAT16 drives in your system will behave like normal drives.

Some programs will need a patch to work properly with a FAT16 drive. One of those programs is COMMAND2.COM, the MSX-DOS2 commandline interpreter. One of the problems is the internal command DIR. Without a patch, it will not display the correct amount of free diskspace. There is already a patch available: PATCHCOM.COM (Made by Okei and Manuel Pazos) It will solve the DIR problem. Just run the program in the directory where your COMMAND2.COM is in. This has to be done only once. (watch out: a patch of COMMAND2.COM version 2.4x is not supported, only version 2.2x or 2.3x)

There are no known problems with the other internal commands (COPY, TYPE, ...), except with CONCAT. CONCAT might not function properly when handling large files, but more details are unknown. If you want to play it safe, don't use CONCAT on FAT16 volumes.

There are other programs, like CHKDSK.COM, which won't work properly on a FAT16 drive. Don't use it.

Also Multi Mente need a patch to work ok:

MM.COM ver 2.07A
Address: 3D5Dh
Change : 'CAh,4Ah,3Eh' to 'C3h,4Ah,3Eh'

MM.COM ver 2.07K
Adrress: 3E0Fh
Change : 'CAh,FCh,3Eh' to 'C3h,FCh,3Eh'

Please use DOS COPY command when coping files.


The FAT16 driver can work together with IDECDEX without problems. So it is possible to copy files from CDROM to a FAT16 partition :)

When the FAT16 driver is installed, some BDOS functions will not be available anymore: #14, #15 (FCB sequential read/write), #67 (format routine) and #68 (creation/destruction of RAMdisk). When these are called an invalid MSX-DOS call error will be returned. So it is not possible to format disks or create/destroy a RAMdisk when the FAT16 driver is active. If you want to do such action, uninstall the FAT16 driver first (FAT16 /R).
Note: using a RAMdisk is no problem if it was installed before the FAT16 driver.

As long a IDEFDISK 3.0 is not ready, you will have to create FAT16 partitions on PC or by manually sector editing. It is also important to note that only so called 'Primary DOS partitions' will be detected by the MSX.

Last minute tests have pointed out that reading Windows9x FAT16 partitions is not always without problems. The computer may crash when accessing certain directories or files. It has probably something to do with long filenames or not completely deleted directory entries.

Have fun with it !
Jon
 
 
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