OSS PING
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The MicroKernel strikes back..
OSS PING
If you are interested in the OSS ping list please mail me
The MicroKernel strikes back..
dosminix, mkfile - Running MINIX 3 under DOS
C:\MINIX> boot disk0.mnx (Typical example)
C:\MINIX> mkfile size disk
This text describes running MINIX 3 under DOS. The DOS ver-
sion of the Boot Monitor, described in monitor(8), grabs as
much memory as DOS is willing to give, loads MINIX 3 into
that memory from the active partition of a "file as disk",
and jumps to the MINIX 3 kernel to let MINIX 3 take control.
As far as DOS is concerned MINIX 3 is just a part of the
boot.com program.
In the example above disk0.mnx is the "file as disk". It is
a file of many megabytes that is used by MINIX 3 as a disk
of four partitions. These partitions will normally be
/dev/dosd1 through /dev/dosd4, with /dev/dosd0 for the whole
"disk". The Boot Monitor will set the dosd0 boot variable
to the name of the disk (its first argument), the root file
system will be the active partition, usually dosd1. It is
better to use the special name bootdev to indicate this dev-
ice, usually in the setting rootdev=bootdev.
Once MINIX 3 is running it will operate the same as if
started from a regular disk partition until it is shut down.
On shutdown from protected mode it will return to the Boot
Monitor prompt, and with the exit command you leave the Boot
Monitor and return to DOS. Shutting down from real mode
will reboot the machine, just like when run from a disk par-
tition. (This more or less crashes DOS, but DOS is used to
such abuse.)
EMM386
MINIX 3 can't run in protected mode (286 or 386 mode) if DOS
is using a memory manager like EMM386. You can either tem-
porarily comment out EMM386 from CONFIG.SYS, or you can
press F8 on startup to bypass CONFIG.SYS. This is only pos-
sible with the later DOS versions.
Windows 95
Press F8 at startup to make the boot menu visible. Choose
"Command prompt", or "Safe mode command prompt" to run DOS.
Use the "safe mode" if EMM386 is started in CONFIG.SYS.
Typing F8 at the right moment isn't easy, so you may want to
change the way Windows boots by editing the MSDOS.SYS file
found in the root directory of your Windows system. This is
alas not trivial. Open a window on your main drive, click
on "View" and choose "Options." In the Options window
choose "View" and enable "Show all files". The MSDOS.SYS
file should now be visible, among several other hidden
files. Right-click on the MSDOS.SYS icon, choose "Proper-
ties" and disable "Read-only". Bring MSDOS.SYS into a sim-
ple text editor such as Notepad. In the [Options] segment
add the following lines (or change existing lines into):
BootMenu=2
BootMenuDelay=5
The first setting makes the Windows boot menu always visi-
ble, and the second line changes the delay before booting to
5 seconds. Take care not to change anything else, or things
will go horribly wrong. Save MSDOS.SYS and exit. Don't
forget to make MSDOS.SYS read-only again, and also hide all
the hidden files again, unless you like it this way.
DOS compatibility box
The 16-bit version of standard MINIX 3 can be run in real
mode in a DOS box. This is somewhat surprising, because it
means Windows 95 simulates devices like the keyboard, timer,
and interrupt controller well enough to fool MINIX 3 into
thinking that all is well. Alas it doesn't work as well
under Windows NT. Keypresses get lost if you type to fast,
and using the floppy occasionally locks MINIX 3 up. This is
a bit disappointing, because it is the only way to run MINIX
3 under NT. Under Windows 95 one is better off putting the
system in DOS at boot and then to run MINIX 3 in protected
mode.
One thing that is better under NT is that the Boot Monitor
is able to get a so-called "Upper Memory Block", thereby
raising useful memory to about 750K. Windows 95 however
hogs leftover UMB memory in a process named vmm32, whatever
that may be. To get some of this memory you can put BOOT /U
at the start of autoexec.bat. The monitor will grab a 64K
UMB if it can get it, and keep that memory safe for use by
MINIX 3 when it is later started from Windows.
The easiest way to start MINIX 3 is to give all MINIX 3 disk
files the suffix MNX. Doubleclick on the disk you want to
run to make the "Open With" window appear. Click on "Other"
and browse to the BOOT.COM program. Set the name of the
.mnx files to "MINIX 3 "disk" file" in the description box
if you want everything right. In the future you can just
click on a MINIX 3 disk file to run it, you don't have to
start a DOS box first. (To make it perfect use "View",
"Options", "File Types", choose "MINIX 3 "disk" file",
"Edit", "Change Icon", "Browse", select MINIX.ICO.)
When MINIX 3 shuts down it will try to reboot what it thinks
is a PC. Windows seems to assume that the DOS session has
exited. Right-click on the BOOT.COM program, "Properties",
"Program", and enable "Close on exit" to make the DOS box
disappear automatically when MINIX 3 thinks it reboots. You
may also want to lock the font to 7x12, or any other font
that isn't ugly.
MINIX 3 disk files are opened in a write-exclusive mode. A
second MINIX 3 session can only open it read-only, which may
lead to a "can't open root device" error.