ACB (compressed archive)

ACB is a compressed archive utility for DOS, and its associated file format. It was developed by George Buyanovsky, and released as shareware.

It appears to have a file patching feature, which it calls "trainable channel mode".

Identification
Based on IDArc and other evidence, the byte at offset 1 is between  and   inclusive, and the byte at offset 3 is.

Software

 * [ ACB v2.00c]
 * old-dos.ru: ACB