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the Minimum computer

The Vsys Development System

The Vsys software development system was written for the purpose of porting Prof. Veltman's algebraic manipulation program, Schoonschip, to the Motorola 680x0 cpu, starting after his arrival at the Physics Department of the University of Michigan in 1981.

Vsys was also used to develop Prof. Veltman's A compiler, for calculations with selectable precision up to 300 digits, with an interface to Vformf, a program for numerical calculation of one-loop Feynman diagrams.

The development system included a macro assembler, linker, loader, debugger, editor, and various utilities, and produced code that was binary compatible with some 13 operating systems, any of which could be used for cross development. See, for example, the Macintosh standard IO page for an enumeration.

One of the systems was that of the Minimum, shown in the photo above, a computer designed and built from scratch by Prof. Veltman and Thom Sterling in the Physics Department. The distribution includes the Minimum operating system.

Among the other systems, the Classic Macintosh was special because it did not have a CLI. Vsys provided one, along with a shell for its use, rather a tour de force at the time.


Currently Vsys runs on five M680x0 emulators for four systems, SheepShaver and Basilisk II for the Classic Macintosh, Previous for the NeXT, FS-UAE for the Amiga, and Hatari for the Atari. Of the four distributions below, the Classic Macintosh is the most complex, because it supplies a graphics shell with its own CLI. The other three rely on the host for CLI services.

The Macintosh and NeXT distributions are nearly complete, with a few unpopulated red links, or orange links that are populated but contain files with unresolved problems. The Amiga and Atari pages are less complete. A few unresolved problems with programs provided in the current distribution are listed in the section Unresolved Problems.

Builds and Cross Builds

Many of the directories in the four distribution trees above contain command files or shell scripts for making executable and other system files. Many are Veltman originals. Some, added for this distribution, track builds and cross builds by including the system number (the standard IO enumeration) in command or command product file names. A c suffix is added for cross builds. Scripts with a system number but no c suffix are are not intended to be run on other systems. Those with a c suffix are functionally identical on all systems, but have shell syntax and command name adjustments according to the specific system tree in which they are found.

Unless otherwise stated, this process has been verified by rebuilding and doing basic tests on the executables for the four legacy systems. The executables actually provided are originals from snapshots of the working systems.

Unresolved Problems

  1. The debugging function of Ldo does not work for new builds under NeXTstep 3.3 with Previous. The workaround is to use the working snapshot version of the Ldo executable.
  2. Builds of the linker for the Macintosh fail with relocation errors under BasiliskII with a Quadra 650 ROM image and Mac OS 8. One workaround is to use the working snapshot version of the Link executable. Another is to use SheepShaver with a New World ROM image and Mac OS 9.
  3. The A compiler does not build properly in this distribution.

Software Licenses

Vsys software is dual-licensed under the GNU Lesser General Public License and the BSD 3Clause License. The aim is to allow the software to be used, published, developed, and modified in the unrestrictive style of public scientific research, while ensuring that there is always a branch of the software which protects free access to the original source and to modifications within that branch.

Vsys is free software. You can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either Version 3 of the license, or (at your option) any later version. See the Free Software Foundation site.

You can also redistribute and/or modify Vsys under the terms of the BSD 3Clause License. See the Open Source Initiative site.

Users who distribute the software with or without modification are encouraged to maintain the dual-licensing system.

Documentation License

Vsys documentation can be redistributed and/or modifed under the terms of the GNU Free Documentation License, either Version 1.3 of the license, or (at your option) any later version, with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. See the Free Software Foundation site.

Except for Schoonschip, which was already open, Prof. Veltman authorized the open release of the binary and source code in the Vsys collection on August 27, 2014, and of the documentation on January 1, 2015.

Copyright © 2014–2022 by David N. Williams, © 2024 by James T. Liu.
Last updated March 16, 2024.
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