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Groups > comp.os.msdos.programmer > #2334

Re: 16 bit code

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"R.Wieser" <address@not.available> wrote in message 
news:583b4895$0$21418$e4fe514c@news.xs4all.nl...
> Bill,
>
>> Now does this look more like it.
>
> Not really I'm afraid.   There are a a number of commands in there that
> simply do not make any sense.  Like the one at 1947:0101, which has BX in
> its target and BH in its source, together with a negative offset.   And
> neither of the registers (BX, DI) are initialised yet.
>
>> I don't see any 32 bit registers there.
>
> And you never will, as DOS-es debug.exe does not know them, and therefore
> can't display them.   Instead you will see DB lines appear (like the one 
> at
> 1947:0100) which indicate an unknown (for debug.exe) machinecode command.
> Some of those DB commands are prefixes, altering the size of a register
> (from BX to EBX perhaps).
>
> Regards,
> Rudy Wieser
>
>
> -- Origional message:
> Bill Cunningham <nospam@nspam.invalid> schreef in berichtnieuws
> o1fd5h$kjt$1@dont-email.me...
>>
>> Now does this look more like it. 16 bit code? I don't see any 32 bit
>> registers there. That I know of.
>>
>> Bill
>>
>> 1947:0100 0F            DB 0F
>> 1947:0101 00B98AFF      ADD [BX+DI+FF8A],BH
>> 1947:0105 F3            REPZ
>> 1947:0106 AE            SCASB
>> 1947:0107 47            INC DI
>> 1947:0108 61            DB 61
>> 1947:0109 031F          ADD BX,[BX]
>> 1947:010B 8BC3          MOV AX,BX
>> 1947:010D 48            DEC AX
>> 1947:010E 12B1048B      ADC DH,[BX+DI+8B04]
>> 1947:0112 C6F70A        MOV BH,0A
>> 1947:0115 0AD0          OR DL,AL
>> 1947:0117 D348DA        ROR WORD PTR [BX+SI-26],CL
>> 1947:011A 2BD0          SUB DX,AX
>> 1947:011C 3400          XOR AL,00
>> 1947:011E 36            SS:
>> 1947:011F 1900          SBB [BX+SI],AX
>>
>> cdrom.sys

    OK I used ndisasm and no switches to see if anything 32 bit might pop 
up. Well there was a tremendous difference. Debug.exe seems to be ok for 
manually changing values in registers and moving them, but doesn't 
unassemble very good.
    A hexdump says this type of file is MZ. Now I have heard of NE files, 
but MZ must be an older file format. And strings in the dump say, "CDDRVR" 
and indictate MS ownership.

Bill

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16 bit code "Bill Cunningham" <nospam@nspam.invalid> - 2016-11-26 16:34 -0500
  Re: 16 bit code Harry Potter <rose.joseph12@yahoo.com> - 2016-11-26 14:38 -0800
    Re: 16 bit code Harry Potter <rose.joseph12@yahoo.com> - 2016-11-26 14:40 -0800
  Re: 16 bit code rridge@csclub.uwaterloo.ca (Ross Ridge) - 2016-11-26 22:58 +0000
    Re: 16 bit code pete@nospam.demon.co.uk - 2016-11-27 07:15 +0000
    Re: 16 bit code rridge@csclub.uwaterloo.ca (Ross Ridge) - 2016-11-27 20:59 +0000
  Re: 16 bit code Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2016-11-26 20:08 -0500
  Re: 16 bit code "R.Wieser" <address@not.available> - 2016-11-27 09:38 +0100
    Re: 16 bit code "Bill Cunningham" <nospam@nspam.invalid> - 2016-11-27 14:37 -0500
      Re: 16 bit code "R.Wieser" <address@not.available> - 2016-11-27 21:42 +0100
      Re: 16 bit code Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2016-11-27 21:20 -0500
    Re: 16 bit code "Bill Cunningham" <nospam@nspam.invalid> - 2016-11-27 14:47 -0500
      Re: 16 bit code "R.Wieser" <address@not.available> - 2016-11-27 21:59 +0100
        Re: 16 bit code "Bill Cunningham" <nospam@nspam.invalid> - 2016-11-27 16:40 -0500
          Re: 16 bit code "R.Wieser" <address@not.available> - 2016-11-28 08:34 +0100
        Re: 16 bit code rugxulo@gmail.com - 2016-11-27 14:08 -0800
          Re: 16 bit code "Bill Cunningham" <nospam@nspam.invalid> - 2016-11-27 17:47 -0500
            Re: 16 bit code "Bill Cunningham" <nospam@nspam.invalid> - 2016-11-27 17:49 -0500
      Re: 16 bit code Jim Leonard <MobyGamer@gmail.com> - 2017-01-04 11:05 -0800

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