William Couture wrote:
> On 10/27/06, Bob Axtell <engineer@neomailbox.com> wrote:
>
>   
>> NONE (not one) application written under DOS6+ by TP5 (Turbo Pascal 5.5
>> for DOS)- which all work
>> fine under a DOS system- will work under WinXP. I just ran thru about 50
>> that I knew were not hardware-related.
>> They would give me a screen OK, but none of the keys or F-keys respond.
>> I can't even EXIT the program.
>>     
>
> Hmmm... that rings a small bell.
>
> I was trying to track down why a program didn't seem to work right
> under a DOS Window, and I found that it was Windows trying to be
> too helpful.
>
> When the program was doing a BIOS call to see if a character was
> waiting, the "BIOS" seemed to be telling itself:
>    Since the keyboards in existance when this BIOS call was originally
>    written didn't have all these extended functions, I'm sure the program
>    doesn't know how to handle them, so I'll just be helpful and remove
>    them so the program isn't confused.
>
> Of course, since *ALL* of the function keys now reply with an extended
> code sequence, not the original code sequence from the IBM-XT keyboard,
> *ALL* of the function keys are "missing" when you call BIOS.
>
> Interstingly, a DOS call does not have that problem (IIRC).
>
> What I wound up doing was the "later", 101-key keyboard BIOS call
> to get the char, and if that failed, then I fell back to the original BIOS
> call.  So, a "check for character and get it if one is waiting" becomes:
>      XOR  AL,AL
>      MOV  AH,11H     ; 101-key keyboard "check for char"
>      INT    16H
>      JC     OLD_BIOS
>      JNZ   GET_CHAR
> OLD_BIOS:
>      MOV  AH,1
>      INT    16H
>      JNZ    GET_CHAR
>      XOR   AX,AX          ; no char waiting
>      JMP   GET_CHAR_DONE
> GET_CHAR:
>      MOV   AH,0
>      INT      16H
>      OR      AL,AL     ; extended keypress (FN key or such)
>      JNZ     GET_CHAR_NORMAL
>      MOV   AL,AH     ; scancode to AL
>      MOV   AH,1       ; flag extended key
>      JMP   GET_CHAR_DONE
> GET_CHAR_NORMAL:
>      MOV   AH,0       ; just a normal character
> GET_CHAR_DONE:
>
> which works fine under any version of DOS with any BIOS.
>
> I'm wondering if you can write a trivial TSR to "fix" TP5 programs.
> Something like:
>    INT16HERE:
>          CMP    AH,1         ; fn = check for keypress?
>          JNE     CONTINUE_INT16
>          MOV   AH,11H      ; change to 101-key check for keypress
>    CONTINUE_INT16:
>          JMP    FAR OLD_INT16_VECTOR
>
>   
>> Its like I am living on another planet... You guys are, like, putting me
>> on, right?
>>     
>
> No, we've just been lucky -- we haven't had "BIOS" (not the REAL BIOS,
> it's part of the XP kernel) try to "HELP" us.
>
> Bill
>
>   
That is an interesting observation. Thanks for the heads-up.
I might tinker with that as soon as some time is freed up.

--Bob

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