RomWBW HBIOS CP/M FAT Utility ("FAT.COM")

Author: Wayne Warthen \ Updated: 6-Jan-2024

This application allows copying files between CP/M filesystems and FAT filesystems (DOS, Windows, Mac, Linux, etc.). The application runs on RomWBW hosted CP/M (and compatible) operating systems. The application also has limited file management capabilities on FAT filesystems including directory listing, renaming, deleting, and sub-directory creation.

Usage:

  FAT DIR <path>
  FAT COPY <src> <dst>
  FAT REN <from> <to>
  FAT DEL <path>[<file>|<dir>]
  FAT MD <path>
  FAT FORMAT <drv>

CP/M filespec: \<d>:FILENAME.EXT (\<d> is CP/M drive letter A-P) \ FAT filespec: \<u>:/DIR/FILENAME.EXT (\<u> is disk unit #)

Notes:

• Partitioned or non-partitioned media is handled automatically. A floppy drive is a good example of a non-partitioned FAT filesystem and will be recognized. Larger media will typically have a partition table which will be recognized by the application to find the FAT filesystem.

• Although RomWBW-style CP/M media does not know anything about partition tables, it is entirely possible to have media that has both CP/M and FAT file systems on it. This is accomplished by creating a FAT filesystem on the media that starts on a track beyond the last track used by CP/M. Each CP/M slice can occupy up to 8MB. So, make sure to start your FAT partition beyond (slice count) * 9MB.

• The application infers whether you are attempting to reference a FAT or CP/M filesystem via the drive specifier (char before ':'). A numeric drive character specifies the HBIOS disk unit number for FAT access. An alpha (A-P) character indicates a CP/M file system access targeting the specified drive letter. If there is no drive character specified, the current CP/M filesystem and current CP/M drive is assumed. For example:

  2:README.TXT refers to FAT file README.TXT on disk unit #2 \ C:README.TXT refers to CP/M file README.TXT on CP/M drive C: \ README.TXT refers to CP/M file README.TXT on current CP/M drive

• FAT files with SYS, HIDDEN, or R/O attributes are not given any special treatment. Such files are found and processed like any other file. However, any attempt to write to a read-only file will fail and the application will abort.

• It is not currently possible to reference CP/M user areas other than the current user. To copy files to alternate user areas, you must switch to the desired user number first or use an additional step to copy the file to the desired user area.

• Accessing FAT filesystems on a floppy requires the use of RomWBW HBIOS v2.9.1-pre.13 or greater.

• Only the first 8 RomWBW disk units (0-7) can be referenced.

• Files written are not verified.

• Wildcard matching in FAT filesystems is a bit unusual as implemented by FatFs. See FatFs documentation.

• The FAT FORMAT command will not perform a physical format on floppy disks. You must use FDU to do this prior to using FAT FORMAT.

• Formatting (FAT FORMAT) of floppies does not work well. The
  underlying FatFs library uses some non-standard fields. The resulting floppy may or may not be useable on other systems. It is best to format a FAT floppy on a Windows or DOS system. You should have no problems copying files to/from such a floppy using FAT.

Known Issues

• CP/M (and workalike) OSes have significant restrictions on filename characters. The FAT application will block any attempt to create a file on the CP/M filesystem containing any of these prohibited characters:

| < > . , ; : ? * [ ] |/ \

The operation will be aborted with "Error: Invalid Path Name" if such a filename character is encountered.

Since MS-DOS does allow some of these characters, you can have issues when copying files from MS-DOS to CP/M if the MS-DOS filenames use these characters. Unfortunately, FAT is not yet smart enough to substitute illegal characters with legal ones. So, you will need to clean the filenames before trying to copy them to CP/M.

• The FAT application does try to detect the scenario where you are copying a file to itself. However, this detection is not perfect and can corrupt a file if it occurs. Be careful to avoid this.

License:

GNU GPLv3 (see file LICENSE.txt)

Build Notes:

• Source is maintained on GitHub at https://github.com/wwarthen/FAT.

• Application is based on FatFs. FatFs source is included. See http://elm-chan.org/fsw/ff/.

• SDCC compiler v4.3 or greater is required to build. New calling conventions introduced in v4.3 are assumed.

• See Build.cmd for sample build script under Windows. References to SDCC must be updated for your environment.

• Note that ff.c (core FatFs code) generates quite a few compiler warnings (all appear to be benign).

To Do:

• Allow ^C to abort any operation in progress.

• Allow referencing more than the first 8 RomWBW disk units.

• Handle wildcards in destination, e.g.:

  FAT REN 2:/*.TXT 2:/*.BAK

• Do something intelligent with R/O and SYS file attributes

• Support UNA

History: