From: Steve Jones <email@example.com>
Subject: Re: Recommended real-time OS for 386EX ?
Isaias Rafael B. Angeles, Jr. wrote:
Niilo Minkkinen wrote:
I noticed that there is some interest in a real-time, MS-DOS
compatible operating system that can load .EXE's built with
DOS tools. There are ten DOS codebases that I know of; some
are commercial and some are freeware (and some are discontinued :).)
Because I wrote a real-time DOS called Embedded DOS 6-XL after
leaving Microsoft's NT group, I had an interest in collecting
these and cataloging them.
Please, recommend OS for embedded ( diskless ) solution using 386EX processor.
There is a free MSDOS compatible OS for the PC line, it is called FREEDOS
and can be found in the INTERNET. This product was inspired by the LINUX
project. They have a freeware C-COMPILER and the C source code for MSDOS
so you can customize it for you application. It is not diskless but you can
work your way around. The files are about 3MB in compressed form and
consumes 10MB when extracted. Maybe you can use this as starting block and
come up with another project for the embedded market. I myself would need
a freeware program like that, so I would support this project if someone
The OS should be royalty-free.
Right now, I do not have the necessary financial support to enable me to
pursue this but I would like to do this in the near future.
I would be interested in the future development of this so I hope you can
include me in your mailing list. I will also keep you my mailing list in
case I find a source for this.
XDOS I obtained from a guy who now works at Phoenix Technologies.
It is small in size, written entirely in assembler, and not real-time
in the sense that it does not provide a way to specify priorities for
codepaths or guarantee delivery of service in a specified amount of time.
It has no scheduler other than the normal "process scheduler" of MS-DOS.
I got full source code and spoke with Thierry Giron, the author, and it's
an all-around good piece of work.
RTDOS written by Mike Podanoffski is an interesting DOS that by its name
and comments in the code would seem to offer threads, timers, and other
stuff common to real-time kernels. It comes in book form and is available
in computer bookstores. It does not actually have real-time elements, but
does have MS-DOS compatible SFT, CDS, and other undocumented structures.
The book is cheap and worth getting because it offers some good information
for those writing a DOS. I wish I had that information before I began,
although there is plenty more that needs to be accumulated before starting
to write your own.
I once looked at the FREEDOS project but was confused about where the
source to the kernel actually was, and it wasn't clear if there was a
real-time scheduler available in the system. I would like to learn more
about it if anyone has a pointer to the code on the net.
There are a bunch of DOSes out there making lots of money of course,
such as DR-DOS (acquired by Novell but dumped after they discovered that
it didn't have a compatible CDS or SFT). Novell DOS 7 is now discontinued,
according to a news bulletin from Novell. That leaves MS-DOS which is
officially dead according to Microsoft, and ROMDOS from datalite (used
typically in mobile electronics according to their literature).
General Software has three DOSes for embedded uses. Since part of the
original mail I'm responding to included an interest in getting the cost
down on such an O/S, I'm providing some basic information here about pricing
and source code availability, but for real detail, please see the web
site or send email directly.
Embedded DOS 6-XL is a fully-reentrant DOS that runs from RAM. It has at
its core a real-time scheduler with threads, timers, mutexes, events, message
ports, queues, and so on. The DOS kernel uses these objects to make sure that
when multithreaded apps use DOS calls simultaneously (i.e., call DOS from
different threads at once), the critical sections of code and data are handled
with kernel objects, not with disabled interrupts. Full source is available
for the system files, device drivers, utilities, and command.com ($2,500).
Royalties are $15/copy and down depending on volume.
The second DOS is called Embedded DOS-ROM, and it runs directly from ROM,
typically in less than 32KB. It has no scheduler. Its goals are to be
small, fast, simple, and low-cost. Full source is available for $995.
Royalties are $7.50/copy and down, depending on volume.
The third DOS is called Mini-DOS, and it is licensed free with our
Embedded BIOS 3.1 product, in the same way that BASIC came with the
IBM PC ROM BIOS. This DOS runs from ROM as a part of the BIOS and
occupies 32KB->64KB, depending on how you configure it. Full source
is standard with the BIOS kit ($4995).
If anyone knows of other DOS codebases, please let me know so I can get
one for my collection. Thanks!
GENERAL SOFTWARE, INC.
Tel. (800) 850-5755 (toll free in US and Canada)
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Fax. (425) 454-5744