MS-DOS 2.0 and "semi compatibles"

I just imaged a disk of an MS-DOS compatible computer (Tandy 2000). Does anyone here know the magic number of an exe under ms-dos 2.0? I had assumed that it was MZ, like current exe files, but I only see 2 or 3 occurrences of this in the entire data stream from the disk. On the plus side, I see LOTS of strings that tell me I have actually read the contents of the disk (this machine used DS/QD drives). Here are some examples: Licensed to Tandy Corp. BIOS version 01.00.00 Copyright 1983 Tandy Corp. All rights reserved. MS-DOS version 02.00.00 Copr. 1981,82,83 Microsoft Corp. I'm guessing I need a good hex editor to look at the directory and offsets to see if they jibe. Any good windows based hex editors (or at least viewers) that anyone can suggest? I'll send the same message to 'classiccmp' Kelly