Re: Disk I/O, BIOS, dosemu, FreeDOS, linux host with Virtual Machines

Bob Masta wrote:

....
Yeah... I'm not so sure about "restart in dos mode". Type "exit", and IIRC you wind up back in Windows. Not what I call "real dos", but it probably is "real" enough for bios interrupts (not "real" enough for Flat Real Mode, IIRC).


The fact that "exit" gets you back to Windows means nothing...

It isn't what I'd consider "normal behavior" for "real dos".

it does a complete reboot to get back there.

Mmmm? My machine was set up with "GUI=0", so a "complete reboot" would have brought me back to "real dos".

My old Daqarta
for DOS is very picky about real mode, and it runs just fine.
It tests the MSW for the PE flag, and won't even start if set.

Well, that proves something...

I haven't tried Flat Real Mode, but I'd be surprised if it didn't
work.

I'm quite sure it didn't - for me. It may be that I didn't have emm386 out of the picture, or something. "loadlin" worked, IIRC...

I have never found anything, nor read anything, to indicate that this is anything other than normal Real Mode.

Perhaps my memory is faulty. I didn't spend too much time in "that dos", as I recall, because it *didn't* seem "normal" to me. Hmmm, I think I know where I might be able to find a drive with a working Win98 on it. (I've been saying I "can't" run Windows... actually, I just "won't"... but maybe I "will"...) If I do, I'll try to investigate what I didn't like about "restart in dos mode" compared to "GUI=0". Your experience probably trumps my memory, but "that's not the way I remember it".

Best,
Frank

This puppy, run in dosemu, is blowin' my mind. Claims real mode. I guess dosemu must be providing me with a fake cr0(?). Jeez, I *hope* I'm not changing the real cr0!!!

org 100h

mov dx, realmsg

mov eax, cr0 ; either of these...
;smsw ax

and eax, 0FFFFFFFEh

mov cr0, eax ; unexpectedly, no complaint
; lmsw ax ; GPF kills dosemu

; smsw ax ; reports v86 mode
mov eax, cr0 ; claims real real mode!!!

test al, 1
jz real
mov dx, v86msg

real:
mov ah, 9
int 21h
ret

realmsg db "real real mode$"
v86msg db "v86 mode$"

.

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