dsktools

DskTools is a library (libdsk) and application (dsktools) for working with TRS-80 Color Computer (CoCo) virtual disk (.DSK) files in JVC format. No JVC header is created or recognized.

Note: By default the original 35 track (160K) format is supported. Starting with v0.4.0 the dsk_new() API has been updated to allow for arbitrary track/side configurations.

Why create this library?

I have a particular fondness for the TRS-80 Color Computer. It was the first computer that I owned and I learned a great deal about programming from tinkering with that machine. Amazingly I still have a functioning device! Using the CoCo SDC from RetroRewind I am able to move files between my CoCo and other devices via SD Card. The Coco SDC accesses files from within virtual disk drives on the SD Card. I needed a way to manipulate DSK files in order to move files to/from my device.

While there are a number of existing tools for working with DSK files, I've never had the opportunity to work directly on a file system. As the DSK format is clearly documented it seemed that DSK files were a good project for learning about the the low-level aspects of file systems.

The original physical floppy disc format is documented here.

Interestingly, Microsoft licensed Basic-69 to Tandy for the Color Computer. This became the basis of the Color BASIC implementation. And the later Disk Extended Color Basic ("DECB") uses an early form of the 8-bit FAT file system from Microsoft BASIC-80. Though most of us know about FAT from PC-DOS and MS-DOS. So this project gave me an opportunity to explore the implementation of a FAT-based system.

Library functions

The libdsk library provides a number of functions for working with DSK files.

Function	Description
dsk_seek_drive	seek to given track and sector
dsk_mount_drive	mount a DSK file
dsk_unmount_drive	unmount a DSK file
dsk_dir	display directory of mounted DSK file
dsk_free_bytes	return number of free bytes on DSK
dsk_free_granules	return number of free granules on DSK
dsk_add_file	add a new file to the DSK
dsk_extract_file	extract a file from the DSK
dsk_new	create a new (empty) DSK file
dsk_format	format a DSK file (erases contents)
dsk_flush	sync directory and FAT to DSK
dsk_del	delete a file from the DSK
dsk_set_output_function	replace the default output function
dsk_rename	rename a file on the DSK

Code Examples

Working with libdsk is straightforward. Simply include dsk.h and link to libdsk and you are ready to begin working with DSK files.

Below is an example of creating a new, empty DSK file.

#include <stdio.h>
#include "dsk.h"

int main(int argc, char *argv[])
{
    // create (and format) a new blank DSK file
    return dsk_new(argv[1]);
}

And here is an example of mounting an existing DSK file and displaying the directory.

#include <stdio.h>
#include "dsk.h"

int main(int argc, char *argv[])
{
    // attempt to mount an existing DSK file
    DSK_Drive *drv = dsk_mount(argv[1]);

    // display the directory
    if (drv)
        dsk_dir(drv);

    return 0;
}

More complete examples of the library and its usage are provided by the dsktools application and related tools.