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Bringing Up CPM68K for the First Time
Bringing up CPM68K (using a 68000, 68010 or 68030 S-100 Board) can be a somewhat daunting task for beginners.  Not only is the hardware different and you have to worry about its (often untested) functionality, but the software is an order of magnitude more complex. 

Way back in the early 1980's Digital Research put out its CPM68K (V1.0) operating system to run on such 68K systems.  It was essentially a conversion of its CPM3 operating system.  Most of the commands and functions were the same as that used for CPM3.  The concept of User Groups and a CPM.SYS file on the disk was carried over from CPM3.

These features included:-

Disk performance, especially random I/O, was improved over that of CP/M v2.2 by hash coding the directory entries and Least Recently Used (LRU) buffering of directory and file data.

The BDOS performed auto-login of removable media drives. The implementation of door open interrupts on removable media drives was highly recommended as an additional check on data integrity and for providing disk I/O performance improvements of up to 30%. The door open interrupt information allowed the BDOS to treat removable media drives in a manner similar to permanent media drives.

The file system capacity was larger allowing a storage capacity of up to 512 megabytes for each of the 16 possible logical drives, and the maximum file size was 32 megabytes. The file system also provided time and date stamping.


Live control characters and type-ahead were supported by cooperating routines in the BDOS and BIOS. The live control characters were CTRL-C, CTRL-S, CTRL-Q, and CTRL-P and their functions were performed when a keyboard interrupt occurred.

The mapping of the logical devices CONIN:, CONOUT:, AUXIN;, AUXOUT:, and LST: onto different physical devices was standardized and made more flexible. This allowed the dynamic remapping of the console to another device, such as a graphics console. Logical device output could be directed to several physical devices at once.

The interface to hardware drivers was greatly simplified and improved by use of a BIOS Kernel. The Kernel was intended for unchanged use in any BIOS implementation.

For a single user efficient operating system this really was what CPM should have been all along.  As we shall see below it is a joy to write a BIOS for its very simple and symmetrical interface. 

That said,  it is not an easy task to build an interface for new 68K hardware.  One really has to be proficient is writing 68K assembly code, programming in C and dealing with an extremely large memory space.

Fortunately for us this has already been done by Damian Wildie in Australia.  The S100 community owes him a big thanks for all this work.  All of Damians work can be see and downloaded from github here.  What I have here is a basic core/summary of that work to get people up and going with CPM68K.

Unless as otherwise started the software below will work for both our 68000/68010 board and 68030 board. The latter being much faster of course.  Both boards use our IDE/CF Card dual drive board.  Other boards include RAM, a console IO and a optional Serial port.  Here is picture of one setup arrangement.
   
  Board Set
    
Please note writing software like this is not easy and definitely not for beginners. That said what Damian has provided is a "black box" arrangement that should allow most S100 bus users to get CPM68K up and running easily and reliable with these boards. Also see the documentation about using CPM68K at the bottom of this page before starting.


Install CPM68K - The Process
There is not enough room in our 68K ROM monitor (at least currently) , to boot and operate CPM68K

Damian has written his own monitor that has a self contained "Boot" module to load up CPM68K from the IDE/CF card drive A:
The complete CPM68K file system is in an ISO file called  cpm68K.iso.  It can be downloaded from the bottom of this page.
(or possibly a more updated file from Damians github site:- https://github.com/dwildie/cpm-68k/releases). 
Here is what the download should look like:-
  
    CF Card Dir
    
You need to "burn" the cpm68K.iso file to a CF card.  There are many ways to do this, I use Etcher, see here.
Under Windows 10 the final CF card "Drive" should appear like this after the cpm68K.iso is "burnt" on to it.
  
  CF Card Dir 2

Next we use either of the two files boot.srec or boot30.srec and use them to burn a special monitor into our CPU boards ROM.
 
Exactly as we did for the 68K Monitor or 60030 Monitor we will burn boot.srec into a Low and High byte of 28C256 ROMs for our 68K board or burn boot30.srec into a 29EE010 ROM for our 68030 board.     

We insert the CF card into the A: drive of then use the Z80 monitor "B" command to activate the 68K or 68030 boards. 

Here is a picture of the initial sign-on screen for boot30 on the 68010 board.
   
  Signon

This is the initial Signon screen.  There are many monitor options. Type HELP to see them listed:-
  
  Help Options
  
As you can see many are similar to the original 68K or 68030 monitor IDE/CF card menu options.
It's important to realize however we are not in CPM68K yet. This is just the ROM monitor, so dir will show you the partitions on the A: drive, not the contents of any one partition.
Most of the above commands are self explanatory from their name.
LBA sets the program pointer to a disk LBA address.  The type and number of partitions is user defined. Damian has 4 on his "CPM68K disk".

You can see in the above example there are 4 partitions on this CF card.  The boot command will always bring up the current partition which on boot-up is always 0.
Typing boot should yield:-
       
  CPM Signon
    
What an amazing sight!  In a few simple moves you have a complete fully functional Digital Research CPM68K Operating System up and running. 
Anybody used to CPM 2.2 or CPM3 will have no problem using the commands and programs. 
The CPM.SYS file is there as is STAT, DDT, ED, PIP etc.  Not all the programs work however, they may be hardware configuration specific.

The CPM-68K System Guide can be downloaded from the bottom of this page.

To change the default partition in the top level monitor (before booting up CPM) you use the monitor command part 1, part 2, part3 etc. Then the boot command will boot up the operating system in that partition.

The above CF Card image has been partitioned into four partitions using DOS/Windows fdisk.  It is really a  test/demo set of images and has several different options for booting on the 68K & 68030 boards.
Use the "part n" command to change partitions, e.g. "part 1" to switch to partition 1.
 
Partition 0
This is a FAT32 partition that contains 4 CP/M disk images.  In CP/M-68K these will be available as disks A, B, C & D.  The drive_a.img is bootable.
As we say above to boot, with partition 0 selected, use the "boot" command.  You will then get a CP/M-68K prompt.
This cpm.sys has been built for the 68010 CPU but will work on both the 68000 & 68030 CPUs.
 
Partition 1
Switch to partition 1 with command "part 1"
This is a native CP/M file system.  It consists of 10 "stacked" 4MB CP/M disks.  These images will appear as drives A - J in CP/M-68K
Use the "dir" command to show the files in the first disk image, this disk is bootable.
To boot, with partition 1 selected, use the "boot" command, You will then get a CP/M-68K prompt.
This cpm.sys has been built for the 68010 CPU but will work on both the 68000 & 68030 CPUs.
 
Partition 2
It has the same as partition 1 but the disk image has not been made bootable.  It must be booted using "boot boot400.sr" and then the CP/M commands applied to make it bootable.
 
Partition 3
It also has the s
ame as partition 0 but uses FAT16 and the disk image has not been made bootable.  It must be booted using "boot boot400.sr" and then the CP/M commands applied to make it bootable


If within the partition 0, after boot,  you go too the B: disk  you will see something like this:-
     
  B Drive
           
The “boot” command in the monitor alone will attempt to boot CP/M68K using the bootloader on the current partition's CPM image system track.  There is a loader on the part 0 disk_a.img's system track and the part 1 system track. If the is no bootloader on a CPM disk's image track e.g. part 2 or part 3 above,  you need to specify “boot boot400.sr” where boot400.sr is picked up from the current partition's file system. Boot tracks in all cases are as defined by "diskdef 4mb-hd-0".  

BTW, For any program you have assembled in s-record format, the boot command can be used to run it.  It is not limited to just boot400.sr.

Here are CP/M commands to create a bootable A: disk
 
A>b:init                 This relocates all the relocatable binaries to absolute .68k format and initializes the assembler.  Only needs to be re-executed if the systems memory configuration changes.
A>b:mkputbt          Assembles, links & relocates the utility to write the boot loader to the disk's boot tracks.
A>b:mkloader         Assembles & links the boot loader and uses the put boot utility to write it to the Disk A boot tracks.
A>b:mkcpm10        Generates a cpm.sys and copies to Drive A.  This version of cpm.sys will work on 68000,68010 & 68030 CPUs.
 
These are all standard CPM submit commands. For example if you look at mkcpm10.sub it will read:-
    
MK CPM
    
Remember now the B: drive above is the drive in the CF card partition 0.  It in not the physical CF card B: on your IDE/CF card board.

Drive A contains standard CP/M commands
Drive B contains command files and source to build the bios, cpm.sys, the boot loader and the utility to write the boot loader to the disk.
   
The disk images produced in Damians github project are not initially bootable.  On the CPM/68K distribution floppies, Digital Research provided cpm400.sr which is CPM/68K without any bios in s-record format intended to be loaded at 400H in RAM. The github project combines cpm400.sr with the assembled bios to produce boot400.sr.  You will find boot400.sr on each partition.  The initial boot of a partition is performed by the monitor loading boot400.sr into memory at address 400H in RAM and jumping to 400IH in RAM to start CP/M-68K, the monitor command to do this is "boot boot400.sr".  Once cpm400.sr is booted, the cmd files on drive B are used to assemble the bios, boot loader, putboot utility and to create cpm.sys.  The putboot utility is then used to write the bootloader to the disk's boot tracks to create a bootable disk.  This creation of the initial cpm.sys must be done using a 68000 CPU (it will fail on a 68010 or 68030).  Once the disk has been made bootable using this process it can be booted with the monitors "boot" command which reads the bootloader from the disk into high memory and jumps to its start address.  The bootloader then loads cpm.sys.  The whole process is similar as to how CPM3 is booted on Z80 systems.

The reason the above initial cpm.sys must be done on a 68000 is because the 68000 did not meet the criteria for virtualization.  For the 68010 and 68030, the MOVE from SR instruction was made privileged.  The assembler & linker (and some other commands) use this instruction.  When cpm.sys is built with the 68010 or 68030 CPU, an exception handler is added which traps the illegal instruction and executes an equivalent.  This way the commands do not need to be recompiled.

Note however, all the code required to generate cpm.sys is on disk B in the above partition 0, you don't need to get anything from github. A 68000 is only required to generate the first cpm.sys.  The original  cpm.sys (boot400.sr) created from the Digital Research cpm400.sr will not work correctly on a 68010 or later CPU.  After the first cpm.sys has been created as described above, a 68010 or 68030 can subsequently be used.
 
Damian also noted that:-
     
      The Digital Research provided cpm400.sr file has a defect which leads to the bios being corrupted.  His github project patches this defect.
      The implemented CP/M-68 bios is a "lightweight" implementation, it uses the monitors functionality to access the Propeller console IO board and IDE/CF Board.
     

You can add additional drives by inserting the CF Card into your windows PC and copying one of the existing images to drive_e.img, drive_f.img, etc.

You select a partition with the part command. 

Remember you can get to any image in any partition from the monitor:-
     
    partitions2


Working with cpmtools and  CPM68K

Many of the above files mentioned above are contained in
.img files.  "Image files" as they are called,  started off as files to store a complete image of a disc for software/game installation files on a CD or DVD. They have now expanded to any file use and any disk type.  There are a number of programs to view and process them.  For CPM file containing image files a popular on is Michael Haardth's cpmtools which can be downloaded from here:-
www.cpm8680.com/cpmtools/cpmtoolsWin32.zip  or the bottom of this page.

This package allows to access CP/M file systems similar to the well-known
mtools package, which accesses MSDOS file systems.  Currently it contains:-
      
cpmls - list sorted directory with output similar to ls, DIR, P2DOS DIR and CP/M3 DIR[FULL]
      
cpmcp - copy files from and to CP/M file systems
      
cpmrm - erase files from CP/M file systems
      
cpmchmod - change file permissions
      
cpmchattr - change file attributes
      
mkfs.cpm - make a CP/M file system
     
 fsck.cpm - check and repair a CP/M file system (only simple errors can be repaired so far). Some images of broken file systems are provided for testing.
      
fsed.cpm - view CP/M file system manual pages for everything including the CP/M file system format

All CP/M file system features are supported. User numbers are specified as
user:file.

Expand the above
.zip file into a new windows directory such as C:\Users\User name\CPM\
Next as an example,  lets download one of Damians disk images: https://github.com/dwildie/cpm-68k/releases/download/V0.0.1/disk1.img  to the same windows directory.
The directory contents should now look like this:-
   
    
    CPMTools Directory

Let's use
cpmtools to see the actual files in disk1.img.
Before we do this however we need to tell cmptools what the disk format of
disk1.img actually is.  Many formats are supplied in the .zip download in the diskdefs file.
However the ones we use here for CPM68K are not. We must open the
diskdefs file and add a few lines that name and describe our new format. 
Use Notepad++ or WordPad (not Notepad) to add the extra addition to the
diskdefs file:-
  
    Diskdef

4mb-hd-0 will be the name of our new format. Then if type:-

cpmls -f 4mb-hd-0 disk1.img

you will see the files present in
disk1.img:-
  disk1
  
There are actually two file types in Damian's disk image files. Some do not have system tracks so in the above we also have a diskdef of "4mb-hd":-
  
   diskdef2
 
and use:-
cpmls -f 4mb-hd disk2.img
 
Other commands include:
To copy a file from the image:
C:\TEMP\cpmtools>cpmcp -f 4mb-hd-0 disk0.img 0:cpm.sys
 

To copy a file to the image:
C:\TEMP\cpmtools>cpmcp -f 4mb-hd-0 disk0.img hello.txt 0:
  

Note also the image files don't have to be in the above CPM directory. Any valid directory path can be used.


Modifying CPM68K BIOS for New Hardware
Let me say right off this is not simple and is definitely not for beginners.  If you are not familiar with Digital Research's CPM systems you should read about modifying a CPM3 system first. See here and here.
Damian's CPM68K github project has everything you need to extend CPM68K to new hardware. You should go to that site and study it extensively.

You can used the gnu 68k cross tool chain to compile, assemble and link the monitors.  The gnu tools are the "standard" build tools for C & C++ on Linux.
They can also be used on Windows, see https://gnutoolchains.com/m68k-elf/

However Damian created a Docker image, source here https://github.com/dwildie/68k-tools, that provides all the tools (gnu, cpmtools, srec_cat, etc.) required to build the project but it excludes the IDE.  

For the IDE, he used Eclipse (which is what Quartus is based on), https://www.eclipse.org/downloads/packages/release/2020-12/r/eclipse-ide-cc-developers and a plugin that he wrote that indexes and hyperlinks the assembler source, auto formats, etc.  This eliminates the frustration and lack of productivity using Easy68K but does not (yet) provide the integrated debugging that easy68k does.




The links below will contain the most recent versions of the above software.
Note, it may change over time and may not correlate exactly with the text in the article above.

CPM-68K System Guide.pdf        
                       (2/8/2021)
CPM-68K Users_Guide.pdf                                          (2/10/2021)
CPM-68K Programmers Guide.pdf                         (2/10/2021)
CPM-68K C Programming Guide.pdf                     (2/10/2021)



boot.srec                                       (2/8/2021)
boot30.srec                                   (2/8/2021)
Boot Files.zip                                (2/8/2021)
cpm68k.iso   (250MG File)                (2/8/2021)
 
cpmtoolsWin32.zip                         (2/8/2021)
disk1.img                                      (2/8/2021)
   

This page was last modified on 02/10/2021