Win95/98 compatible FAT filesystem handler for AmigaOS.

Based on Torsten Jager's fat95 v3.18 (Aminet: disk/misc/fat95.lha).

fat95 handler

Download at GitHub Releases

Purpose

"fat95" is a DOS handler to mount and use Win95/98 volumes just as if they were AMIGA volumes.

Personal Note

Improvements to this handler are developed in my free time. If you'd like to support ongoing maintenance and experimentation, you can do so on Ko-fi.

Community Links

• English Amiga Forum Thread: Discussion Thread user questions and troubleshooting.
• Aminet fat95 Advanced Search: FAT95 releases (m68k, AmigaOS) shows all fat95 packages.

System Requirements

• Every AMIGA, OS 1.3+ (OS 2.0+ for full functionality)
• A suitable device file for low level disk access, like the mfm.device for floppies, compactflash.device for CF in PCMCIA.

Features

• Workbench and applications support
• Diskchange autosense
• Format type autosense: FAT12, FAT16 and FAT32
• MBR and GPT partition table support
• Simple LINUX style partition selection or manual definition
• Up to 4 GBytes of partition size for FAT16
• Large harddisk support via TD64 or direct SCSI
• Long filenames (up to 104 chars for now)
• Inquiry, read, write, and maintenance access
• Built-in error check utility
• Disk formatting using the OS 2.0+ format command
• MS-DOS 8.3 downward compatibility
• User definable language and code page
• Date range Jan 1st, 1980 through Dec 31st, 2107
• Extended datestamp support: creation date and time, last accessed date (written automatically, readable as file comment text)
• Volume serial number as name for unnamed volumes
• Automatic directory optimization
• Written entirely in assembly language

What's New in

3.19 (01.02.2026)

• Fork of 3.18

  • Set English as default localization for fat95 handler
  • Rebuild by vasm 2.0d
  • Consolidated documentation into fat95.guide

• Detect SFS/PFS/FFS/RDB as foreign disk formats

• GPT partition table support

  • Automatic detection of GPT disks via protective MBR (type 0xEE)
  • Scans GPT partition entries for Microsoft Basic Data partitions (FAT)
  • Supports partition selection via DosType (same as MBR: FAT\1, FAT\2, etc.)

• Improved disk change handling

  • Non-existent partitions now show "No Disk" instead of "Uninitialized"
  • Fixes stale partition data when switching to cards with fewer partitions (see Disk Status Meanings)
  • Foreign disk formats (RDB, PFS, SFS) show appropriate status per partition

• Bug fixes

  • Fixed trailing slashes in path names (e.g., "makedir cf0:temp/" now correctly creates "temp") WARNING: Using trailing slashes with 3.18 corrupted the filesystem

Installation

Introduction

Installing disk drives under AmigaOS requires two components:

1. A hardware driver that provides block-level access to the drive. This can be part of the Kickstart ROM (e.g., trackdisk.device) or a separate file (e.g., Devs:compactflash.device).
2. A filesystem handler that manages partitions, directories, and files. The standard filesystem is in ROM. Others, like fat95, are files in the L: drawer.

These two components are connected via a mountlist - a configuration file that tells AmigaOS how to mount the drive.

Installation

1. Edit the install_fat95 text file for your language.
2. Double-click the install_fat95 icon to activate the changes.
3. Optionally double-click example mountlist icons in DOSDrivers/:
   • MS0/MS1 - FAT-formatted PC DD 720k floppy (mfm.device)
   • CF0 - FAT partition on CompactFlash in PCMCIA slot (compactflash.device), supports MBR and GPT For custom configurations, see the Mountlist Configuration section.
4. Copy mountlists to:
   • DEVS:DOSDrivers/ for automatic mounting at boot, or
   • SYS:Storage/DOSDrives/ for manual mounting via shell command (Method A: Shell Command)

Mountlist Configuration

Device Driver Settings

First, the name of the driver:

Device = scsi.device

That's the one responsible for the Amiga's internal IDE or SCSI port. Usually, multiple drives can be connected to such a port. Therefore, we need to state which one we want:

Unit = 1

This is the "slave" IDE drive (e.g., a ZIP drive). The "master" harddisk has number 0. For drivers with a single drive only, it is also 0.

Flags = 0

Some drivers allow special settings to be made via this one. Most cases, that 0 is enough.

BufMemType = 1
MaxTransfer = 0x20000
Mask = 0xfffffffe

For the (unpatched) A1200 ROM scsi.device. Or if driver doesn't need them, simply discard.

File System Settings

Filesystem = l:fat95

AmigaOS wants the full path here.

StackSize = 4096

Reserve that many bytes for temporary data. State too few, and "mysterious" crashes will happen.

GlobVec = -1

fat95 is assembly language written, so -1.

Buffers = 200

Hold that many blocks of 512 bytes each in memory. More = Faster = Less memory available.

Control Options

Control = "+s"

Available options:

Option	Description	Default
+	Turn ON the following options	-
-	Turn OFF the following options	-
s	Force direct SCSI reads/writes (for >4GB disks)	OFF
d	Display extra datestamp info as file comments	ON
D	Record "last accessed" date on file reads	ON
l	Show 8.3 filenames lowercase (e.g., "test.txt")	OFF
L	Show 8.3 filenames with uppercase initial (e.g., "Test.txt")	OFF

Startup Options

Activate = 1

Start immediately instead of on first access.

Partition Selection

fat95 supports both MBR and GPT partition tables with automatic detection.

Automatic Partition Search (Recommended)

LowCyl = 0              /* Enable auto search */

BlockSize = 512         /* Required by Mount command */
HighCyl = 1
BlocksPerTrack = 1
Surfaces = 1

DosType Values

The DosType controls which partition to mount:

DosType	Hex Value	Description
FAT\0	0x46415400	Floppies only
FAT\1	0x46415401	First FAT partition (recommended)
FAT\2	0x46415402	Second FAT partition
FAT\3	0x46415403	Third FAT partition
FAT\4	0x46415404	Fourth FAT partition
FAT\5	0x46415405	First logical drive (extended partition)
FAT\6	0x46415406	Second logical drive, etc.

Recognized partition types:

For MBR disks, fat95 recognizes these partition types:

Type	Description
0x01	FAT12
0x04	FAT16, < 32 MB
0x06	FAT16, >= 32 MB
0x0B	FAT32
0x0C	FAT32, LBA
0x0E	FAT16, LBA
0x05, 0x0F	Extended partition (for logical partitions)

For GPT disks, fat95 counts only FAT partitions (Microsoft Basic Data GUID: EBD0A0A2-B9E5-4433-87C0-68B6B72699C7). Non-FAT partitions (EFI System, Windows Recovery, etc.) are automatically skipped.

GPT vs MBR Detection

fat95 automatically detects the partition table type:

1. Reads block 0 (MBR)
2. Checks for protective MBR (partition type 0xEE)
3. If found, reads GPT header at LBA 1 and scans GPT entries
4. Otherwise, parses standard MBR partition table

Manual Partition Definition

For special cases like damaged partition tables:

BlockSize = 512
DosType = 0x46415401

BlocksPerTrack = 1
Surfaces = 1
LowCyl = <StartBlockNumber>
HighCyl = <LastBlock>

Mounting the Drive

Complete Mountlist Example

CF0:
    FileSystem     = L:fat95
    Device         = compactflash.device
    Unit           = 0
    Flags          = 0
    LowCyl         = 0          /* Auto partition search */
    HighCyl        = 1
    Surfaces       = 1
    BlocksPerTrack = 1
    BlockSize      = 512
    Buffers        = 200
    BufMemType     = 1
    MaxTransfer    = 0x1FE00
    Mask           = 0xFFFFFFFE
    StackSize      = 4096
    Priority       = 5
    GlobVec        = -1
    DosType        = 0x46415401 /* FAT\1 = first FAT partition */
    Activate       = 1

Method A: Shell Command

mount CF0:

Method B: Workbench Icon

1. Create project icon CF0.info
2. Enter c:mount as the default tool
3. Double click the icon

Method C: Auto-mount at Boot

Copy both CF0 and CF0.info to DEVS:DOSDrivers

Method D: OS 1.3 (MountList file)

Edit DEVS:MountList and append:

CF0:
    Device = scsi.device
    /* ... other entries ... */

Then mount with:

mount CF0:

Special Features

fat95 uses file comments for special commands:

Scandisk

filenote CF0:anyfile "!scandisk"

Recovers lost files and fixes disk errors.

Control Options

filenote CF0:anyfile "!control -dD"

Changes configuration options at runtime.

Security Erase

filenote CF0:anyfile "!erase"

Overwrites deleted files with zeroes (unrecoverable delete). Works with CompactFlash built-in erase when available.

Note: scandisk and erase can be aborted with <ESC>.

Troubleshooting

Report issues at: https://github.com/pulchart/fat95/issues

Q: "object not found" when mounting?

A: Check the Device =, Unit = and Flags = entries.

Debug tool:

debug95 CF0: ram:cf0.log

Creates a dump of internal fat95 variables for diagnosis.

FAT32 Notes

• FAT32 FAT table can be huge (8MB for 8GB partition)
• fat95 does not cache entire FAT32 table to save memory
• Free space calculation happens after mount ("volume is validating")

Disk Status Meanings

Fat95 reports different disk statuses depending on what it finds:

Status	ID	Icon	Meaning
Mounted	ID_DOS	Volume name	FAT partition found and mounted successfully
Uninitialized	ID_NDOS	CF0:NDOS or CF0:Uninitialized	Disk present but not FAT format (e.g., RDB, PFS, SFS, FFS) or bad MBR partition table
No Disk	ID_NONE	(none)	No media inserted OR requested partition doesn't exist
Unreadable	ID_BAD	CF0:BAD	Disk read error or hardware failure
Busy	ID_BUSY	CF0:BUSY	Handler is inhibited (via INHIBIT command)

Partition specific behavior

When you have multiple mount points (e.g., FAT\1, FAT\2, FAT\3) and insert a disk:

Scenario	FAT\1	FAT\2	FAT\3
3-partition FAT disk	Mounted	Mounted	Mounted
1-partition FAT disk	Mounted	No Disk	No Disk
RDB/PFS/SFS disk	Uninitialized	No Disk	No Disk
No disk inserted	No Disk	No Disk	No Disk

This behavior ensures:

• FAT\1 correctly shows "Uninitialized" for foreign formats (disk present, wrong type)
• FAT\2, FAT\3, etc. correctly show "No Disk" when the requested partition doesn't exist

The exact status shown may depend on the order of disk insertion and reinsertion.

Tools Included

Tool	Description
l/fat95	FAT95 filesystem handler
l/install95	Locale installer (read/write locale files)
c/dd	Raw block transfer tool
c/debug95	Debug information tool
c/SetFileSize	File size modification utility
c/boot95	Boot partition creation tool

dd Usage

Copy disk blocks to file:

dd scsi.device 1 ram:dump 0 128

Write file back to disk:

dd ram:dump scsi.device 1 0 128

Debug95

Creates a dump of internal fat95 variables for diagnosis.

debug95 CF0: ram:cf0.log

boot95

Booting from FAT Partition

boot95 CF0:

This installs an Amiga automount sequence in the unused area between the MBR and first partition (~30KB). Requires fat95 in L: drawer.

Caution: Overwrites existing Amiga style partitioning info.

License

GNU LGPL v2.1

History

Version	Date	Changes
v3.19	02/2026	GPT partition table support, improved disk change handling, Fixed trailing slashes in path names
v3.18	03/2013	Open source release LGPL (Torsten Jager)
v3.17	-	No info
v3.16	-	No info
v3.15	05/2004	Added "l" option (lowercase 8.3 names)
v3.14	05/2004	Added "L" option (uppercase initial)
v3.13	02/2004	PalmOS formatted memory card support
v3.12	11/2003	Alternative disk recognition via SCSI, optional TD_UPDATE, faster small writes
v3.11	08/2003	Optimized short name generator, directory updates during writes
v3.10	07/2003	Fixed directory creation bugs, international character fixes
v3.09	04/2003	Security erase feature, abortable scandisk
v3.08	10/2002	Skipped version number
v3.07	09/2002	File writing fix, SCSI auto-select, Hungarian localization
v3.06	08/2002	Faster small file access
v3.05	07/2002	New configuration options
v3.04	07/2002	Removed startup messages, scandisk fixes, improved dd tool
v3.03	05/2002	Removed DiskUpdate error message
v3.02	03/2002	Directory creation fix, FAT12 CF card formatting, SCSI error checking
v3.01	02/2002	Minor short name bug fix
v3.00	02/2002	User character set for 8.3 names, official FAT32 cluster sizes
v2.19	01/2002	Filenames up to 104 characters
v2.18	12/2001	SetFileSize() support, user language support
v2.17	09/2001	Faster FAT32, Amiga reformatted ZIPs recognized
v2.16	08/2001	MaxTransfer fix, FileSystem.resource code sharing
v2.15	05/2001	Crash fixes, pure attribute, error check, boot95 tool
v2.14	03/2001	FAT32 mode bug fix
v2.13	02/2001	New buffering system
v2.12	02/2001	SCSI direct command support
v2.11	12/2000	Better FDA compatibility
v2.10	10/2000	Exotic partition tables, TD64 error requester
v2.9	09/2000	AddBuffers fix, safer CURRENT_VOLUME, trackwise access
v2.8	08/2000	Software write protection, fat95debug tool
v2.7	08/2000	Logical drive recognition fix
v2.6	07/2000	Disk full crash fix, inconsistent file access fix
v2.5	07/2000	Track-wise buffering, FAT32 free space fix
v2.4	07/2000	Exclusive locks fix, 8.3 name fixes
v2.3	07/2000	Native ExAll(), ChangeMode(), various bugfixes
v2.2	06/2000	Restart validator, 65-char filenames, FAT32 formatting
v2.1	04/2000	NSD and TD64 support, FAT32 28-bit fix, timestamp fix
v2.0	04/2000	First FAT32 support
v1.22	03/2000	Large sectors fix (>512 bytes)
v1.21	03/2000	Cluster-wise file access, diskchange messages
v1.20	03/2000	Separate caches, workbench icon suppression
v1.19	03/2000	Partition selection fix
v1.18	03/2000	First partition support
v1.17	02/2000	Second published version, improved FORMAT
v1.16	-	No info
v1.15	02/2000	Code optimizations
v1.14	02/2000	FAT copy update fix
v1.13	02/2000	SERIALIZE_DISK fix
v1.12	01/2000	ETD commands, SERIALIZE_DISK, faster FAT16 writeback
v1.11	01/2000	Device workarounds, faster drawer operations
v1.10	-	No info
v1.9	-	No info
v1.8	01/2000	Workaround for register-trashing devices
v1.7	01/2000	Formatting fix, double-mount crash fix, reentrant code
v1.6	12/1999	Large partition fix, SID2 workaround, serial number, dir optimization
v1.5	11/1999	First published version