This is ZSID v1.4. It is a Z80 debugger. There were evidently a couple of 
problems with this program. The files in this ZIP file are :

ZSID.COM      - The original unmodified program.
ZSID-FIX.DOC  - A file describing a patch.
ZSID-PAT.COM  - ZSID.COM with the above patch applied.

ZSID.PAT      - A file describing a different patch. This patch has NOT
                been applied to the ZSID.CON file.