An operating system for multiprocessor networks of Z-80-based computers.

About TurboDOS:

TurboDOS is an operating system developed around middle eighty by Software 2000 Inc. It has many interesting features for the era expecially considering targeted hardware: Z80 based systems initially and then 8086. It was capable to compete not only with MP/M from Digital Reaserch, but for some aspects even with Unix systems running on much more expensive hardware.

"The multiprocessor nature of TurboDOS is its most unique feature. Unlike other operating systems where networking of processors is a recent add-on, or which really only support a file transfer protocol, TurboDOS was designed from the ground up as a multiprocessor operating system. This means that the application program does not have to be aware of the nature of the hardware configuration it is running on. It can run in a single-user system, a network master (Server), or a network slave (Requestor), with no modification. The user has a consistent operating method in all of these same environments. He does not have to pay attention to loading his networking package, nor does he have to modify the application software. In all cases, TurboDOS allows each user the private use of single-user software and data bases, and also allows complete sharing of files, if the application has been written with multiuser shared data bases in mind. In effect, a TurboDOS network system can be viewed as a single computer, in which each user has access to any resource in the system, if allowed by his privilege level and configuration."
William Schultz, 1983

In effect the most relevant features as claimed by Software 2000:

  • Networking Capability
    TurboDOS has the ability to coordinate a "network" of interconnected microcomputers. Generally a separate microcomputer/cpu supports each users's terminal. One or more additional micro manage the disks, printers, and other shared resources of the system.
    This approach (one user/one cpu) would enable excellent performance, given the hardware of reference, compared with solutions in time-share.
  • CP/M and PC-DOS Compatibility
    TurboDOS offers compatibility with (any?) program written for CP/M and MP/M, accessing the largest library of applications for the time. Compatibility should be granted for applications from: CP/M-80 2.2, CP/M-86-1.1, CP/M Plus, MP/M-II, Concurrent CP/M-86 and MP/M-86.
    Additionally it includes an emulator to run many of the programs written for (IBM) PC-DOS.
  • Performance
    Software 2000 asserted that independent benchmarks showed TurboDOS to perform much better in file-intensive applications than CP/M or MP/M (probably due to the use of cache) with an average at least three times as fast. "The more users on your system, the greater the performance advantage becomes".
  • Disk Capacity
    Compared with other systems (CP/M is always the reference here) TurboDOS lets you store 25% to 35% more data on each floppy disk by using a more efficient format of storage. TurboDOS can handle bigger hard disk up to 1Gb without partitioning and supprt files up to 134 megabytes.
  • Reliability
    TurboDOS implements a set of features for data integrity and error recovery. Most notably it does read-after-write of all disk updates.
TurboDOS was designed with OEM distribution in mind. So it has a modular structure distributed in form of relocatable files. A different combination of this modules builds a kernel suitable for the target system: single or multi-user, disk server, printer spooler server and so on.
It was distributed by many vendors, the most notables was MuSYS and IMS.
For multiprocessor systems you can combine any type of Z80 and 8086 processors, they can be fitted into the same shassis using (tipically) MuSYS S100 SBC boards or using distinct systems interconnected via serial lines or even ethernet. TurboDOS call these systems "tightly-coupled" and "loosely-coupled".
Single processor/ single user systems can also be configured but without time-sharing support.

TurboDOS today:

This operating system has not had all the attention it deserved, so it seems almost disappeared.
Recently, however, the CP/M community has been very active in the recovery of this OS, begun from Emmanuel Roche who recover and retyped documentation.
Mario Viara contributed with a port of TurboDOS 1.2 on Udo's z80pack emulator.

The great news went on the work of Per Frejvall who has a copy of TurboDOS 1.41 and ported it on
simh/AltairZ80 environment.
Per's work remarkable by itself (he ported hardware drivers after a work of disassembly ie: without assembler sources) has lead him to contact Mike Busch on suggestion of Andrew Lynch about TurboDOS licensing.
Mike Bush and Ron Raikes are the founders of Software 2000 Inc.
This is the result, quoted from Per's post on comp.os.cpm:

TurboDOS is now free!

Bearer of good news, it is good to be!

Message from Mike Busch, co-founder of Software 2000 and creator of

"Per, Software 2000, Inc. Is no longer enforcing its copyright on
TurboDOS. Have fun with it, and thanks for asking. Mike

Can you ask for more?
The bad part is that they don't have sources anymore.


"TurboDOS was known, when CP/M ruled, as the only serious opponent to MP/M-II, the multi-user, multi-tasking version of CP/M. Recently, there were mention of this lost DOS, and I had the idea to search for it. I found a Newsletter for TurboDOS were Mr. R. Roger Breton was mentioned, managed to find him, and he agreed to release his 500-pages book about TurboDOS. Let us hope that this masterwork will lead to the ressurrection of TurboDOS."

Indefatigable Roche send me "Z-80 ASSEMBLY LANGUAGE UNDER TurboDOS" the book written by Mr. Breton, to made it publicly available with his kindly permission.
The book is distributed as a zip file containing four version of the book itself, to be printed on differents paper sizes, single or double sided.
Mr. Breton has a copyright on the book, that is free just for PERSONAL-USE ONLY. He also ask for the book to be distributed in the zip-file form only.

And here it is: Z80_Assm.zip.

Please look at the "Read_Me_First.pdf" into the archive for more information about personal-use and distribution license.

If you want more informations about TurboDOS, read this document that Emmanuel Roche has fully retyped for us:



TurboDOS 1.4x manual can be found here at bitsavers.org.
Another complete copy of the manual for Z80 1.41 version of TurboDOS, provided by me, can be downloaded from here:

Release Notes for 1.41 work in progress *
TurboDOS 1.4 User's Guide work in progress *
MOVE-IT User's Manual work in progress *
TurboTOOLS Volume 1 work in progress *
MuASM TurboDOS/Z80 Macro Assembler work in progress *
Interprocessor/Intersystem networking with the MuSYS implementation of TurboDOS done
Product Support Notes done
TurboDOS 1.4 Z80 Implementor's Guide done
TurboDOS 1.4 Z80 Programmer's Guide done

* Document scanning is in progress.

Documentation for MuSYS Net/82 Single Board Computer from s100computers.com is also available.

NorthStar and TurboDOS:
http://www.hartetechnologies.com/manuals/Northstar/North Star Facts about Horizon 8-16 with TurboDOS.pdf


Mario Viara:



Per Frejvall:
Per says this is just a preview of his work. Nonetheless it is functional, you can grab and test it.
Any new release will be inserted here.

Some TurboDOS software is also available in local mirrors of:

Fritz Chwolka archive (mix of software and documentation)
oak.oakland.edu ftp archive

External links:

An effort similar to what is on this page is going on at Bill Buckel's site: The TurboDOS museum.
Herb Johnson has setup a page on "Software 2000 Inc. and TurboDOS", complete and concise in his nice journalistic style.
TurboDOS on Wikipedia.

MuSYS TurboDOS brochures:

You can also download a brochure and advertisements of the products by MuSys Corp. clicking on the miniature below.

Musys Brochure m-musys-advertise-alltog m-musys-advertise-net82 m-musys-advertise-tdos


APSAS - Particle Analysis System on TurboDOS 1.22(large pdf manual)