CBM File

What are CBM files and how to open them

Are you having problems opening a CBM file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CBM files.

What is a CBM file?

CBM files have multiple uses, and 64 Colors BitMap is one of them. Read more about the other uses further down the page.

64 Colors BitMap

We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

How to open CBM files

Important: Different programs may use files with the CBM file extension for different purposes, so unless you are sure which format your CBM file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested eight different CBM openers which you will find listed below.

Last updated: August 31, 2026

All known file formats using extension .CBM

While 64 Colors BitMap is a popular type of CBM-file, we know of 2 different uses of the .CBM file extension. Different software may use files with the same extension for different types of data.

Doodle Bitmap

Doodle Bitmap is a graphics file format used with the Doodle program on the Commodore 64, a drawing and sketchpad application written by Mark R. Rubin and released in 1983 by Omni Software. It produces high-resolution black-and-white style images (hi-res bitmap mode, 320×200 pixels) with selectable foreground and background colors. The format stores the bitmap and a per-8×8-block color attribute so that each 8×8 region on screen has one background and one foreground color. Its main use is saving images created in Doodle for later loading, printing, or conversion.

Doodle Bitmap files are created by Doodle when a picture is saved uncompressed. The graphics data occupies a fixed block of memory in the C64 at address $5C00. The first 584 bytes (from $5C00 to $5FE7) record color information for the 40×25 character blocks (one byte per 8×8 block: high nibble for the "off" pixels, low nibble for the "on" pixels). The following 8192 bytes (from $6000 to $7F3F) carry the bitmap data (one bit per pixel for full 320×200 hi-res). The disk-file length is always 9216 bytes (37 blocks on a standard 1541 disk). Doodle also supports a compressed version prefixed "jj" using RLE, though the original Doodle program cannot read or write that one.

Files begin with a load address of $5C00 so that loading them into RAM maps correctly to the color-block area, followed immediately by the bitmap data. The byte signature at offset 0 in such a file is the two bytes representing the load address - namely hexadecimal 5C 00.

Various apps that use files with this extension

These apps are known to open certain types of CBM files. Remember, different programs may use CBM files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about CBM file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.