File Access


Frodo offers four possibilities for the 1541 emulation:

1. Host system directory (Directory Mode)

In this mode, the C64 programs and files are stored in a directory on your computer and can be LOADed and SAVEd as usual from the emulator. The paths to the directories of the simulated drives are given in the settings window in the “Drive Paths” group.

You can also load the directory with LOAD"$",8. All files are displayed as having type “PRG”, all subdirectories as type “DIR”. To get into a subdirectory you have to open the settings window and change the path for the drive, as the operating system of the C64 doesn't know about subdirectories. However, it is possible to use a '/' in the C64 file name to access files in subdirectories (for example LOAD"GAMES/ELITE",8), unless the '/' translation setting is turned on.

For opening files, the file types 'P' and 'S' and the access modes 'R', 'W' and 'A' are supported. Wildcards ('*', '?') can also be used. Files are always overwritten by the SAVE command even if they are not opened with “@:”. Floppy commands other than 'I' and 'UJ', relative files, and direct block access are not implemented. You can however read the error channel.

2. .d64/.x64 disk image file (Disk Image Mode)

Most C64 programs available on the internet and on software collections, expecially demos and games, are stored in files with the extension “.d64”. Such a file holds all 683 blocks of a complete side of a 1541 disk, so that direct block access is possible from within the emulation. The path name of the disk image file must be given in the settings window in “Drive Paths” group.

Apart from .d64 files, Frodo can also use image files of the “x64” emulator, automatically detecting the file type.

3. .t64/LYNX archive file (Tape/Archive Mode)

.t64 and LYNX (.lnx) files are archive files like “tar”. .t64 files are also sometimes found on the internet and on software collections; LYNX is a native C64 archiver. Frodo's .t64 support is a bit special in that it doesn't treat the .t64 file like a tape image (that's what the .t64 format was originally designed for), but rather like a disk image file.

When loading the directory with LOAD"$",8, Frodo creates a listing of all files within the archive. You cannot write to .t64 or LYNX files, they are read-only under Frodo.

4. Processor-level 1541 emulation

The 1541 is an “intelligent” disk drive with its own CPU and memory that executes code concurrently to the C64 and can even be programmed from the C64 side. Frodo is able to emulate a 1541 on this level, but as this notably slows down all disk accesses, the 1541 processor emulation can be turned on and off from the settings.

If the 1541 processor emulation is turned on, only drive number 8 in Disk Image Mode is available. The .d64/.x64/.g64 file to be used must be selected in the drive path field of drive 8.