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Introduction:

• Generic Z80 CPU emulation with ICE like user interface, similar to hardware emulators from Zilog and Mostek
• Z80 cross assembler to bootstrap a Z80 system from an UNIX host
• Emulation of a complete system for running CP/M 1, CP/M 2, CPM 3 and MP/M 2 (bootable OS disk images included)
• Emulation of an Altair 8800 system with Z80 CPU, 64KB RAM, front panel and SIO connected to the terminal
• Emulation of an IMSAI 8080 system with Z80 CPU, 64KB RAM, front panel and SIO connected to the terminal

So instead an emulation of a virtual complete computer system capable of runnning CP/M 1, CP/M 2, CP/M 3 and MP/M 2 has been build, as an example for what can be done with this software. The Z80 cross assembler was used to bootstrap CP/M 2.2 on the system, for CP/M 3 and MP/M 2 the loader BIOS's were written on an UNIX host, final work then was done under CP/M 2.2 running on the emulated system.

This virtual computer system has been used then to rebuild CP/M 1, CP/M 2, CP/M 3 and MP/M 2 completely from the sources. Also example implementations of CP/NET have been build, to network the virtual systems with this very early form of RPC (remote procedure calls). Additional disk images with all sources, tools and build scripts are available for download.

The system also runs the UCSD p-System Versions I.4, I.5, II.0 and IV.0. Disk images for a ready-to-run system as well as sources to rebuild the Z80 version are available in the download section.

Features of this virtual computer system:

• Lightning fast Z80 CPU, 1GHz clock frequency doable on consumer PC's
• Clock generator tunable in 1MHz steps, helpful for video games
• Up to 16MB RAM, banked into 256 segments with programmable MMU. Size of segments adjustable in 256 byte page increment
• 4 x IBM 8" SD compatible floppy disk drives
• 2 x 4MB harddisk drives
• 1 x 512MB harddisk drive
• 1 x serial console port connected to the CRT
• 5 x serial ports connected to TCP/IP ports for more MP/M terminals and CP/NET networking of multiple systems
• 1 x serial auxiliary port
• 1 x printer port
• 10ms interrupt timer, used for MP/M and RTO's
• hardware clock, readonly, uses date and time information from host

The Z80 core then was used together with John Kichury's front panel library, to build exact emulations of the Altair 8800 and IMSA 8080 computer systems, that can be fully operated via the front panel identical to the original machines. The IMSAI 3D computer model build by John is really stunning, see the screenshots at the link below.

For seeing the machinery in action here are some screenshots showing the emulated systems.

The whole package is written in ANSI C for POSIX compatible Open Systems. Systems on which the sources are known to compile without any changes are:

• OpenBSD 3.9
• NetBSD 3.0.1
• Linux x86 and x86-64 distributions like: Suse 9.x and 10.x, Fedora Core, andLinux
• Solaris 9 with GNU C for SPARC
• Windows 2K/XP with Cygwin, some additional informations can be read here

Other ports to Microsoft Windows have been done, links are in the download section.

All Digital Research CP/M material included was taken from The Unofficial CP/M Web site, the license for this material can be read there.
Other commercial CP/M material included was taken from CP/M Commercial Software Archive.
Some user written tools were taken from the Oak CP/M archive.
Various programs from the Walnut Creek CP/M CD-ROM have been used too, an online copy is available here.
The UCSD p-System on 8" disk images is available at Bitsavers.

Quickstart to run the Digital Research OS's:

1. Download the z80pack source archive
2. Unpack the source archive in your home directory: tar xzvf z80pack-x.y.tgz
3. Compile the CP/M emulation:
   1. cd ~/z80pack-x.y/cpmsim/srcsim
   2. make
   3. make clean
4. Compile support programs, some are needed for the emulation:
   1. Releases before 1.15: cd ~/z80pack-x.y/cpmsim/srccpm2, Releases 1.15 and later: cd ~/z80pack-x.y/cpmsim/srctools
   2. make
   3. make clean
5. MAKE BACKUPS OF THE BOOTABLE DISK IMAGES:
   1. cd ~/z80pack-x.y/cpmsim/disks/library
   2. cp * ../backups
6. To run CP/M 2.2:
   1. cd ~/z80pack-x.y/cpmsim
   2. ./cpm2
   3. To leave the emulation type a:bye. This program executes a Z80 HALT instruction which terminates the emulator.
7. To run CP/M 3:
   1. cd ~/z80pack-x.y/cpmsim
   2. ./cpm3
   3. To leave the emulation type a:bye. This program executes a Z80 HALT instruction which terminates the emulator.
8. To run MP/M 2:
   1. cd ~/z80pack-x.y/cpmsim
   2. ./mpm
      This boots CP/M 2.2, the system tracks of the disk do not contain the mpmldr program. To boot MP/M type mpmldr which runs the loader under CP/M 2.2 and boots the MP/M 2 system from the disks.
   3. To leave the emulation type a:bye. This program executes a Z80 HALT instruction which terminates the emulation.
9. To exchange files between the UNIX host and the CP/M disk images download and install cpmtools. The emulator uses 8" SD disk drives as the first 4 drives, which also is the default used in cpmtools version 2.7 at the time of this writing. In case it changes sometime, the disk definition is:
   

   	diskdef ibm-3740
   	  seclen 128
   	  tracks 77
   	  sectrk 26
   	  blocksize 1024
   	  maxdir 64
   	  skew 6
   	  boottrk 2
   	  os p2dos
   	end
   

   Caution, while the data tracks have a skew of 6 the system tracks have a skew of 1, because I never implemented skews in the UNIX putsys programs. Using the correct skew made sense with Shugart floppy disk drives from 1976. Nowadays with harddisks used in personal computers transferring 40MB/s and more the skew is only used for compatibility reasons.

   To access the 4MB harddisk image of z80pack add the following disk definition to /usr/local/share/diskdefs:
   

   	diskdef hd
   	  seclen 128
   	  tracks 255
   	  sectrk 128
   	  blocksize 2048
   	  maxdir 1024
   	  skew 0
   	  boottrk 0
   	  os 2.2
   	end
   

   To access the 512MB harddisk image add this disk definition to /usr/local/share/diskdefs:
   

   	diskdef hdb
   	  seclen 128
   	  tracks 256
   	  sectrk 16384
   	  blocksize 16384
   	  maxdir 8192
   	  skew 0
   	  boottrk 0
   	  os 2.2
   	end
   

   To access the 4MB harddisk image (drives I: and J:) from the UNIX host always use the option -f hd as in this example: cpmls -f hd disks/drivei.cpm. Do not forget to use it, specially when copying files to the disk, without this option the harddisk image will be destroyed. You did make backups of the disks, did you?

   Same with the 512MB drive P:, always use the option -f hdb to access this drive file.

10. Start reading documentation, understanding the disk image layout under ~/z80pack-x.y/cpmsim/disks is essential.

Quickstart to run UCSD p-System:

1. Download the z80pack source archive
2. Unpack the source archive in your home directory: tar xzvf z80pack-x.y.tgz
3. Compile the CP/M emulation:
   1. cd ~/z80pack-x.y/cpmsim/srcsim
   2. make
   3. make clean
4. Compile support programs, some are needed for the emulation:
   1. Releases before 1.15: cd ~/z80pack-x.y/cpmsim/srccpm2, Releases 1.15 and later: cd ~/z80pack-x.y/cpmsim/srctools
   2. make
   3. make clean
5. Download the UCSD boot images
6. Unpack the archive in ~/z80pack-x.y/cpmsim: tar xzvf ucsd-ix.tgz
7. MAKE BACKUPS OF THE BOOTABLE DISK IMAGES:
   1. cd ~/z80pack-x.y/cpmsim/disks/library
   2. cp * ../backups
8. To run UCSD p-System:
   1. cd ~/z80pack-x.y/cpmsim
   2. ./ucsd-i4 or ./ucsd-i5 or ./ucsd-ii or ./ucsd-iv
   3. To leave the emulation first shutdown the UCSD p-System from main menu with the H command, then abort cpmsim with CTRL-\
9. To exchange files between the UNIX host and UCSD disk images download and install UCSD filesystem tools.

Downloads:

Documentation:

Support:

Copyright, License and all that stuff:

Bibliography:

1. Everything to know about the Z80 including original Zilog data sheets can be read here.
2. Digital Research manuals for CP/M 1, CP/M 2, CP/M 3, MP/M 2, assemblers, linkers and compilers are archived here.

Other Z80 hardware and software related links:

Links to informations about the UCSD p-System:

Some other UNIX Z80 emulations:

Z80 emulation written in Java:

Some links to informations about the Altair 8800:

Some links to informations about the IMSAI 8080:

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