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echo: alt_dos
to: All
from: Jacob Brewer
date: 2003-12-08 08:45:48
subject: RE: DR Dos on a P4

From: Jacob Brewer 

Thank you, that fixed my problem.  

The Win98 EMM386 (I need that for SoundBlaster) still craps out, but the Dr.
DOS EMM386 seems to run well with the win98 himem with the exception of a
warning that says it should be used by itself (EMM386 for DR.DOS only allows
up to 64MB of memory).  

I know have access to all memory!

Thank you,

Jacob

Jacob B. Brewer
Software Engineer
Oasis Gaming USA
www.oasisgamingusa.com http://www.oasisgamingusa.com> 


-----Original Message-----
From: Michal H. Tyc [mailto:mht{at}bttr-software.de]
Sent: Friday, December 05, 2003 5:58 PM
To: opendos{at}delorie.com
Subject: Re: DR Dos on a P4


Oh, my first message to the list was rejected too...

Let's try again:

; CLRVDISK.COM
; Clear VDISK signature in HMA if A20 enabled at boot time,
;   which happens on some systems (as Toshiba Satellite 300CDS)
;   and causes memory manager initialization error
; Add INSTALL=CLRVDISK.COM in [D]CONFIG.SYS before the memory
;   manager; this works under DR-DOS only, as MS-DOS processes
;   INSTALL= directives too late
; Intel syntax (NASM), 80386+

  org 100h

  xor bx, bx
  mov ds, bx              ; ds = 0
  dec bx
  mov es, bx              ; es = 0FFFFh
  mov bx, 200h            ; word to compare: unused INT 80h vector
  mov di, 10h             ; offset of HMA in segment 0FFFFh
  mov ax, [bx]
  cmp ax, [es:bx + di]    ; 20-bit address wrap test
  jne clear               ; words differ, A20 enabled
  not dword [es:bx + di]  ; not sure yet, try modifying HMA
  cmp ax, [bx]
  jne done                ; 0:200h changed, so A20 is disabled
clear:
  cld
  mov cx, di              ; length = 10h words, dest = HMA start
  xor ax, ax
  rep stosw               ; clear VDISK header (if any)
done:
  ret                     ; return via INT 20h

The binary is attached in a private message.

Hope this helps,

Michal


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