Newsgroups: comp.os.linux.announce
Path: sparky!uunet!!emory!gatech!!!!caen!batcomputer!theory.TC.Cornell.EDU!mdw
Message-ID: <>
Originator: m...@theory.TC.Cornell.EDU
Keywords: dosemu emulator v0.47
Organization: Cornell Theory Center
Date: Thu, 28 Jan 1993 18:46:12 GMT
Approved: (Matt Welsh)
Lines: 347

ANNOUNCEMENT!  I am releasing dosemu 0.47 alpha for public consumption!

I have put dosemu47.tar.Z onto in the
/pub/linux/ALPHA/dosemu directory.

dosemu47.tar.Z is a collection of my enhanced sources to the MS-DOS
emulator originally written by Matthias Lautner.  Note that the term
MS-DOS emulator is a misnomer, as you must have a copy of MS-DOS to
boot it.  I doubt this is a problem for anybody.

Below I have included my README.first file from that distribution as a
"document" of its new features.  Please get it and try it out.

Robert Sanders

========================== DOS EMULATOR 0.47 ===========================
      Robert Sanders                 

						January 27, 1993

Hello, public,

This is my latest version of the DOS emulator; I call it dosemu47,
meaning dosemu 0.47 alpha. I hope the numbering doesn't confuse
anybody.  0.41-0.46 were "internal" versions.  The RCS revision numbers
printed in various places throughout the emulator mean very little to
either of us, so don't worry about them.

It is based on dosemu0.4 from Matthias Lautner, but is quite a bit
more useable.  It is probably already obsolete by now, however, as I
am continually at work making the code even uglier :-).  Hopefully,
with all this code uglification will come a stray feature or two.

I apologize for the vaporfeatures I promised.  Dosemu still doesn't
support virtualized UARTs, and print jobs still aren't queued after a
given no-print time.  The former was sabotaged by a filesystem crash
(although it was never really done, anyway), while the latter was
sabotaged by laziness and time pressures at school.  I will have these
features done, given time.

Before you boot the MicroBeast, there are some things you'll need to do.
  1) edit the file emu.c to suit your system (see README, and below).
  2) compile it.  "make install" does it best.  if you have gcc 2.3.3,
     edit the Makefile to give the path to your shared library stubs.
  3) Edit your termcap to have a few new fields (at least new to the standard
     SLS termcap.)  Here's mine:


vs|xterm|vs100|xterm terminal emulator (X Window System):\

The new fields are vi,ve,vs (set cursor visibility); a lot of fields
may have changed (I forget).  You might want to compare the whole
thing to your termcap and just change the differences, or make this
termcap "consdos" or something.  It works well for me.  I have noticed
that programs, such as qedit, which use different sets of character
attributes to create menu selection bars will not work with my current
termcap translation scheme.  I suggest you remove vi,ve,and vs from
your termcap if you find that to be the case: this will at least make
sure the emulator doesn't hide the cursor, so you can find your place.

I'm still trying to devise a way to map a variety of foreground and
background colors, as well as high intensity, onto a very few
termcap attributes.

  4) If you're using the raw keyboard (-k) option, you will probably want
     to change the kernel to allow you an easy way out in case things crash
     or otherwise become sticky.  This is the tiny patch I use in 0.99pl4
     (this is not a real diff!):

	if (vc_kbd_flag(kbd,VC_RAW)) {
		kbd_flags = 0;
+		if (scancode == 0x54) clr_vc_kbd_flag(kbd,VC_RAW);
		goto end_kbd_intr;
+	else if (scancode == 0x54) set_vc_kbd_flag(kbd,VC_RAW);
	if (scancode == 0xe0) {

	This basically gives you the key SysRq (right alt + print screen)
	to switch between RAW and XLATE modes.  You shouldn't ever have
	to do this in a normal situation, and once I rewrite a few things
	in the emulator, you'll never have to.  Patience, little ones.

	I suggest you not use this feature of the DOS emulator unless you
	really need it.  It gives you some debatably useful things like
	alt/ctrl/shift key flags (through int16h and the Bios Data Area),
	but it's not necessary.

  5) I recommend that you use
  6) If you plan to use raw console video (-c), make a kernel or LILO
     image spec. that will boot into 80x25 mode.  Although it isn't
     overpolished yet, raw console video mode is nice.  You get colors
     and the DOS character set.  Highly recommended if you can stand
     80x25 console screens.
  7) If you want to run .EXE files from your DOS partition, edit emu.c
     to include your hard drive's geometry (the whole thing, not just your
     DOS partition.)  This is of great functionality, but I don't like
     it because of the danger.  Otherwise, you'll have to run LINUX.EXE
     as specified in README, and that won't let you run .EXE files from
     the phantom drive (yet).  However, you can still run .EXE files
     from floppies, diskimage, and hdimage.

-------- INVOCATION --------
Here is what you see if you type "dos -?":

usage: dos [-ACrwdvckDbV] [-m SIZE] [-P FILE] [-H|F #disks] > doserr
    -A boot from first defined floppy disk (A)
    -C boot from first defined hard disk (C)
    -r,w report debug messages for disk read/write
    -d report DOS calls
    -v report video calls
    -c use PC console video (kernel 0.99pl3+) (!%)
    -k use PC console keyboard (kernel 0.99pl3+) (!)
    -m set memory size to SIZE kilobytes (!)
    -D report unrecognized interrupts
    -P copy debugging output to FILE
    -b map BIOS into emulator RAM (%)
    -H specify number of hard disks (1 or 2)
    -F specify number of floppy disks (1-4)
    -V use VGA specific video optimizations (!%)
    -N No boot of DOS

     (%) marks those options which require dos be run as root (i.e. suid)

The invocation I use under an 80x25 console window is this:
    dos -ckbm 720 -VP /dev/ttys0 > dosdbg

Under an xterm*:
    dos -b -P /dev/ttys0 > dosdbg
* I recommend that you resize the xterm to 25 lines first. The standard 24
  is insufficient.  Larger sizes will have no affect.

Using "-k" direct console keyboard, there are a few things you should know:
every key is interpreted in scancode form by the emulator.  The current
emulator has support for only the US keyboard.  You may copy the
appropriate data structure out of the kernel if you require an
alternate keyboard. I apologize to non-U.S. users for the inconvenience.
This will be addressed in future versions.

(Note: this was true for 0.98pl? when I copied the data structures.
       0.99 sources may have changed the structure.)  

VC switching is accomplished by using LeftAlt+Fn, where RightAlt-Fn
gives you an alt-fkey as in normal DOS.  Otherwise, any key
combination (except the pause key) will act exactly as it would under
native DOS.

-------- KEYBOARD -------
Once again, I recommend you not use the -k (raw console keyboard)
option unless you really need it, and that if you do, you apply the
kernel patch listed above.  If the emulator crashes or for any reason
does not process any BIOS keyboard requests for a while, you will not
be able to switch VC's.  (If you have an external terminal, you can
kill -HUP the emulator process to fix things).

-------- VGA VIDEO ------
All I'll say about the -V flag is that you have to have also specified
-c (raw console video) to use it, and that you shouldn't specify this option
unless you're sure you really have a VGA card installed.  This option
currently only changes the mapping of the high character attribute bit,
but it will do more in the future.  Use it at your own risk.
(If you see programs with blinking text where you think there shouldn't
 be any, try -cV)

The "-P /dev/ttys0" sends a copy of dosdbg (the debugging messages) to
my dumb terminal.  It can be left out if you wish (or have nothing on
/dev/ttys0!).  This is no big deal, basically just a tee.  The reason
it's there at all is that it will one day provide me with a debugging
menu system.  (One day, like everything else :-).

----------- BIOS --------------
The "-b" option maps the two BIOS ROMs at c000:0000 and f000:0000 into
the emulator's address space (same addresses).  This is for my
purposes, and does not (yet) enhance the functionality of the emulator.
I'm not sure if all computers have their ROMs at those addresses.

----------- SERIAL --------------
 The emulator supports BIOS-accessed serial ports.  This is a feature
of limited usefulness, and great capacity to suck CPU time.  It was
easy to implement, so i did.  It's very stupid now, and isn't likely
to change anytime soon.  I successfully used MS-Kermit to log into my
school's Sequent using the emulator now, so the fun is over.

The emulator assumes COM1 is /dev/modem (on my system, a symlink to
/dev/ttys0), and the COM2-COM4 are the files doscom2, doscom3, and doscom4
in the current directory.  These should also be symlinks to real devices.
You can change these names directly in emu.c (see the comnames[] array).

----------- PRINTERS ------------
The emulator supports printing to LPT1, LPT2, and LPT3.  The output from
these "virtual printers" is dumped into the files dosemulpt1, dosemulpt2,
and dosemulpt3, respectively.  You can change these names in emu.c
(see the lptnames[] array).  I can't guarantee that these files are
fully up-to-date until you exit the emulator.  

I'll revamp the print handling later.  It works for now.

----------- MEMORY SIZE ---------
If you need extra memory, you can use the "-m" switch to set the
memory size.  This switch specifies, in Kilobytes, how much main memory
the emulator has available.  The default is 640, although the emulator
allows up to 734.  I believe that even 734K is safe, although too much
over that intrudes on the screen memory at b800:0000.  When I add
real VGA video, this option will be unsafe, as VGA memory starts at

I've just gotten some pretty extensive docs on EMS, so I hope to have
EMS at least buggily implemented by some time or other, give or take a
while.  It won't hard...all the hard work has been done by giving the
emulator 32-bit access to DOS RAM.  I don't have docs on XMS yet.

Note that the EMS implementation won't require that you load an
external EMM386.SYS file or anything.  It will be inherent in the
emulator code.  In fact, the emulator requires that you not load
some sort of external memory manager :-).

----------- HARD DISKS --------
My current setup in emu.c has two hard disks: hdimage (C:)*, and
direct access to my DOS partition (D:).  It has two floppies, a
"diskimage" Linux file (A:), and my first floppies (B:).  I currently
have floppy B: set as a 1.2 MB 5 1/4 in drive.  Look in the top
portions of emu.c on how to change this (with SMALL_FLOPPY and
LARGE_FLOPPY).  You can have the emulator use more floppies by
adding them to the table in emu.c and giving dos the parameter
-F num.  Having more than 2 floppies defined will cause LINUX.EXE
to fail.

* The drive specifications in parentheses refer to the dos emulator's
  view of the world, not your normal, real-DOS letters

The "hdimage" and "diskimage" files must exist at dos invocation time.
Only one of them need be bootable; and they can be of any size.
In fact, with this installation, you only need to "touch diskimage"
in the dosemu directory to make it work.  You may then format the A:
disk to make "diskimage" into an accessible disk.  The hdimage will
grow to accomodate your usage of it (contary to myth, it will NOT

To boot from diskimage, "dos -A > dosdbg" will work.  You can make a bootable
diskimage by copying one from your /dev/fdX, where X is 0 or 1. This would
look like:
   dd if=/dev/fdX of=diskimage bs=1024 count=1440
   dd if=/dev/fdX of=diskimage bs=1024 count=1200
depending on whether it is a 1.44 MB or 1.2 MB drive.

Note that diskimage is currently set up to look like a 3.5 in 1.44 meg
drive.  You can easily change it to be a 5.25 in "drive."  This is
slightly explained at the top of emu.c.   You should have the specification
for diskimage match that of the boot disk you wish to copy into
the file "diskimage."

Also note that you can change the first entry in disktab to be a
physical drive, and the emulator will boot from that one if given the -A

If you do not want to have direct access to your hard drive, change
HDISKS to 1 in emu.c.  Then you may invoke LINUX.EXE to set up your
/usr/dos partition as drive d:.

-------- EVERYTHING -----
The code is a heap right now.  Bear with me.

-------- TIDBITS --------
Try to save the debugging messages (dosdbg file) for any bugs or
problems that you find.  They are more helpful to me than descriptions

-------- EXITING --------
To kill the dos emulator, execute the EXITEMU.COM file found on the
included hdimage, or send a SIGTERM or SIGHUP signal to it.  If you
need to simulate a ctrl-break in the emulator, you can send it a SIGQUIT
from somewhere else.
Sending a SIGKILL to the emulator is a poor decision.  This will not
allow the emulator to restore the state of the tty, restore the state
of the screen, or flush all open files, including the debugging file.
Use SIGTERM and SIGHUP instead.

-------- BUGS -----------
I probably already know about the lack of features in dosemu47, so
please don't tell me "It won't recognize my mouse."  However, if you
do find some bug that you think OUGHT to work, please do write me and
tell me about it.  Also, if you have some fairly simple feature that
you really need NOW, I can be flexible.

I've fixed too any bugs to count in dosemu0.4, so I won't list them
here.  I've probably introduced as many, though, so watch out.

If the emulator crashes on you, the first thing you should do is examine
the dosdbg file for any line beginning with "ERROR:"; look at the last
such line first.


Robert Sanders

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