S100 Computers

A Versafloppy II Diagnostic Program
Please click here for detailed information about the Versafloppy II S-100 board hardware. SD Systems provided a basic diagnostic program to help you get their hardware up and running. They also provided the source code for a CPM BIOS.

The Versafloppy II manual can be seen here Versafloppy II.pdf
You can view the code here.
The code itself can be downloaded by clicking on SD-DDBIOS.

VF.Z80
Because a good reliable Floppy disk hookup is so essential to putting together a solid reliable S-100 system I felt the need for an improved Versafloppy II diagnostic program. Particularly in the case of formatting, reading, and writing to 5" floppies. SD Systems provided the ability only to work with their single and double density 5" format. Unfortunately nobody else uses that format. I took a table driven approach to disk parameters in the software allowing you to write disks in essentially any format. I have included 12 of the most common types including the IBM-PC CPM86 and MSDOS.

Probably most critical is the need for basic functions like continuous track seeks, sector reads track reads etc when you are trying to repair hardware or get it going the first time. The program VF.COM was written with this in mind.

The diagnostic program source VF.Z80 code can be seen here. The code itself can be downloaded by clicking here

Please look at the first few pages of EQU 's before assembling. In particular make sure you set the TRUE/FALSE for the 1791 or 1995 chip you are using. Also set the base port for your board. I use 50H to avoid conflicts with a Lomas Video board I have. . SD Systems uses 60H.

As you can see the program is written in Z80 code. It should assemble with a few changes with almost any Z80 assembler.
To review and download a CPM assembler go here.