>Bonjour All,

>Can someone tell me what I have to do to about the following problem?

>I programed a simple game (boresome!) on a 80486-66 MHz or something.
>But when I run it on my own computer (Pentium-150) it goes a LOT faster.

>I tried to compute the video speed and correct the delay function to
>that video speed. It doesn't work (perhaps my way of computing the
>v.speed is incorrect, but I don't think so).

> In article <330E0B40.1...@cpedu.rug.nl>, S.J.B...@cpedu.rug.nl says:

> >Bonjour All,

> >Can someone tell me what I have to do to about the following problem?

> >I programed a simple game (boresome!) on a 80486-66 MHz or something.
> >But when I run it on my own computer (Pentium-150) it goes a LOT faster.

> >I tried to compute the video speed and correct the delay function to
> >that video speed. It doesn't work (perhaps my way of computing the
> >v.speed is incorrect, but I don't think so).

> A simple way to get a fixed (on a fast enough computer) rate is to
> poll the lowest byte of the system time kept at the constant memory
> address of [$0040:$006c] (or [Seg0040:$006c] if you target also
> protected mode). Something like

> var
>   old_time:byte;

> ...
>   repeat
>     old_time:=mem[Seg0040:$006c];
>     do one cycle of the game
>     repeat until old_time<>mem[Seg0040:$006c]
> {* This last line will procduse CPU-speed independent delay,
> also takes into account the difference in time spent on computing
> one cycle of the game *}
>   until game_ends;

> A more popular method seems to be to synchronize your game with the
> vertical retrace. I don't know how to achieve that, as I have had
> satisfactorily little flicker in my simple games simply by using
> an offscreen buffer and doing all rendering there and copying the
> entire buffer to video mem once every 55 milliseconds (= the frame
> rate you get with the above code). Probably the game programmer's
> encyclopedia (available e.g. from x2ftp.oulu.fi) will tell you how
> to do that.

> Hope this helps,

>         Jyrki

> label
>         l1, l2;
> asm
>                 mov dx,3DAh
> l1:
>                 in al,dx
>     and al,08h
>                 jnz l1
> l2:
>                 in al,dx
>                 and al,08h
>                 jz  l2
> end;

> procedure waitretrace;assembler;
> asm
>    mov dx,3DAh
> @@l1:
>    in al,dx
>    and al,08h
>    jnz @@l1
> @@l2:
>    in al,dx
>    and al,08h
>    jz @@l2
> end;
> =
> Looks alot better to me, and it can't be "missused".

> Asbj?rn wrote:

> > Just one stupid question: Why don't you use local labels?

> > procedure waitretrace;assembler;
> > asm
> >    mov dx,3DAh
> > @@l1:
> >    in al,dx
> >    and al,08h
> >    jnz @@l1
> > @@l2:
> >    in al,dx
> >    and al,08h
> >    jz @@l2
> > end;

> > Looks alot better to me, and it can't be "missused".

> Just one stupid question:  Why use @@ when @ to precede a label should
> be sufficient?  Is there really any difference there?  If so, I've never
> noticed one.  (Okay, so maybe that's *two* stupid questions.  :-)

>> Just one stupid question: Why don't you use local labels?

>> procedure waitretrace;assembler;
>> asm
>>    mov dx,3DAh
>> @@l1:
>>    in al,dx
>>    and al,08h
>>    jnz @@l1
>> @@l2:
>>    in al,dx
>>    and al,08h
>>    jz @@l2
>> end;

>Just one stupid question:  Why use @@ when @ to precede a label should
>be sufficient?  Is there really any difference there?  If so, I've never
>noticed one.  (Okay, so maybe that's *two* stupid questions.  :-)