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S-100 Software

This section of this web site is dedicated to software to run on S-100 systems.  Clearly this could be a whole web site in itself. I will concentrate here on software that is focused on getting the hardware up and running and that I have either written myself or have used extensively.

MASTER.Z80  --  A System PROM monitor
A Z80 Monitor Program   This is ROM based Zapple like monitor program for a Z80.  It is a menu driven ROM based program to allow you to bring up a basic functional system. It is toughly documented to allow its adaption to most hardware configurations.
  Master PROM Menu

  --  A Diagnostic Program  for the SD Systems Floppy disk controller board

A Versafloppy II Diagnostic Program    This is a diagnostic program for a Versafloppy II disk controller board.  Again it is menu driven to allow you to bring up a basic functional system.
  VF Menu

SIO8.Z80  -- A Diagnostic Program for the SD Systems Serial IO/Clock Board.
This is a very powerful 8 Port Serial (RS232) I/O board. See here for a detailed description.
I have written a little program to configure the Serial Ports and Time/Clock chip on this board. It can be see here, and downloaded here.  As usual it can be easily modified for the same chip on other boards.
  SIO8 menu

Besides containing four Zilog 8530 dual serial I/O chips, this board also has a National Semiconductor MM58167 Clock/Calendar chip. The above program also allows the on board clock chip to be set and read. However for the S100Cpmputers  custom built PIC/RTC board (which also utilizes the MM58167), see below, a more extensive and detailed program was written. That program will also work with this board.

PCGET.ASM and  PCPUT.ASM  --  A Way of Moving Files Back & Forth Between S-100 Computers and an IBM PC.
Often it is nice to be able to move a CP/M or other S-100 based programs (Monitor, diagnostics etc.) up to a PC. There it can be used as a backup storage area or assembled/run on a PC based Z80/CPM simulator. To do this one needs a way to conveniently get data back and forth. You could use a 5" floppy (on an old PC) and configure the S-100 system to read the disk, or use one of the older PC disk format reading programs and go in the other direction.

I opted for a simpler approach. I modified one of the many versions of Ward Christenson's CP/M's  "Modem Program" to simply pass files back and forth over a serial link. I use a USB->Serial connector on the PC and the SD Systems IO8 Serial board on the S-100 end. (With slight modifications any serial board can be used). The original program is stripped down to simply accept (or send) a file named in the CP/M command line.
  PCGet Menu

The program to upload a CP/M file to a PC is PCPUT.COM. The source can be seen here.
The program to download from a PC a file to a CP/M system is PCGET.COM. The source can be seen here.
Both of these programs should be assembled with Digital Research's MAC assembler.  This program can be obtained here.
The serial ports sections of both programs should be modified for your own hardware.

The Zip file of both programs can be obtained here.

If you are up to it, you can use the CP/M program "LU" to compress many CP/M files into one large file, upload that "library" file and extract files out on the PC side (using a CP/M simulator).  LU.COM can be obtained here.

On the PC end one can use any number of PC based serial port Modem programs. They should be capable of utilizing the original "XModem" protocol, not the newer "XModem (crc)" or "XModem (1K)" protocols.  I particularly like Celestial Software's  Absolute Telnet program. They have a free "light version" and a "Professional version" for $50. The latter is well worth it as it has many other additional useful features.

-- Running CPM3 on a PC
In much of my development work for building CPM programs for my S-100 system I actually build, edit, assemble and sometimes even execute the program first on an IBM PC  using Windows XP or Windows 7.  One day I hope to have an S-100 video board of the resolution that current PC video boards have but for now, nothing compares with the editing convenience of Microsoft's Visual Studio when working with .Z80 or .ASM files.
  Running Example (Small)

While you can edit the programs under windows (Visual Studio), you need a "CPM emulator" to assemble them and/or execute them.  There are a few good CPM emulators for the PC available.  I like to work with Peter Schorn's AltairZ80 Simulator. He has put an enormous amount of work into building a Windows based program that behaves as if your PC was a S-100 Altair computer.  Start with this documentation for some background information.  However to assemble and run your own CPM programs you only need to launch the CPM3 emulator within the Altair.com program itself. From then on (transparent to you) you are operating under CPM3 in a Windows box. The necessary software and instructions are all described here.

Software for the  S100Computers & NVRAM S-100  IDE Board
An S-100 IDE Hard Disk Controller Board 
Andrew Lynch and I have constructed an S-100 board that allows one to interface an IDE hard drive (or memory board) to the S-100 bus.  Relative to the old ST-506 Winchester drives, IDE drives are simple to interface, quiet, and inexpensive.  All the software for that board can be found here.
  IDE Signon
Software for the S100Computers & NVRAM
PIC & RTC S-100 Board

A PIC and RTC S-100  Board  Andrew Lynch and I have constructed an Priority Interrupt and Real Time Clock S-100 board that allows one to utilize the interrupt structure of the S-100 bus with both 8 and 16 bit CPU's.  The board also contains a National Semiconductor MM58167 Clock/Calendar chip.  This is really two S-100 boards in one.  Example software for interrupt testing can be seen here, and downloaded here.   Software for the RTC chip and checking its functionality worth CPM3's date and time stamping capability can be seen here, and downloaded here.

  58167 registers2

A Collection of CPM based 8080/Z80/8086 Assemblers and Linkers.
Over the years I utilized a number of assemblers and linkers. Each had its own advantage and quirks.  I have put together a collection of some of the better ones in one spot for easy downloads.  They include the following (in no particular order) ....

TDL's Z80 Macro Assembler.
Cromemco's Z80 Assembler.
Digital Research's MAC and RMAC
Digital Research's ASM86
Microsoft's M80 and L80
SD Systems ZASM

They are all briefly discussed and can be downloaded here

A Collection of Useful Assembly Language Routines
Check here for a collection of small but useful Z80, 8080 and 8086 Assembly Language routines I use time and time again in programs.

Bringing Up CPM3 for the First Time (Writing a CPM3 BIOS for the S-100 ZFDC FDC Board)
Most early S-100 Computer systems used CPM2.2 (or earlier) as the basic computer disk operating system.  The system was fairly simple to implement and was the germination base for much of the microcomputer worlds software.  The system however had many limitations in particular it was designed for a standard 8" IBM single density single sided floppy disk with 128 byte sectors.  As newer disk sizes and formats started to appear -- particularly hard disks, the system started to show its limitations.  Digital Research's answer was CPM3.  This version of CPM allowed essentially any sector size and disk format to be used easily and efficiently.  What CPM3 did was hide within the operation system itself the 128 byte sector size requirement and allow the BIOS to work easily with any sector size "transparently". The system had an  elaborate disk hashing/data buffering system as well.  Of particular usefulness was the fact that it existed in two forms. A "standard" NON BANKED version that operated like CPM2.2 in a Z80 system with 64K (or less) of RAM.

However there was a much more efficient "BANKED" version of CPM3 which by using onboard 'bank switching" hardware, could utilize up to (in theory) many megabytes of RAM. Typically 128K or 256K RAM systems were used.   This allowed for a very fast and sophisticated system with for example things like file time and date stamping. 

It should be noted that this BANKED system absolutely requires that the Z80 can switch in and out a portion of its 64K adders space with other RAM boards.  There were a number of ways this was done in hardware.  The Cromemco and Godbout systems utilized an IO port to switch RAM boards.  Intersystem's and our own S100Computes/N8VEM Z80 board, use on-board Z80 CPU board hardware to extend the addressing range of the Z80.  We will discuss this later.

For now lets start with a very simple CPM3 BIOS.  We will step by step build the system up to a much more complex setup. Eventually arriving at a BANKED system with multiple floppy, hard and memory disk connections.  
Please click here to read about this process.

Bringing Up CPM3 for the First Time
(Writing a CPM3 BIOS for an S-100 IDE Hard Disk or CF Card)

This section is an extension of the above CPM3 for a floppy disk except that now we will boot CPM3 up from a Hard Disk
Please click here to read about this process.

Bringing Up CPM86+ for the First Time
(Writing a CPM86+ BIOS for the Dual S-100 IDE and ZFDC Boards)

This section is devoted to beginners trying to implement CPM86+ in their S-100 system.  Obviously the system must have an 8686 (or above) CPU board.   The details and examples given are quite general and can be applied to any capable S-100 system. However all the examples are centered around our Dual IDE and ZFDC disk controllers.
Please click here to read about this process.


This page was last modified on 06/21/2011