Re: A82: Re: i gots a kwestun 4 yous people
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Re: A82: Re: i gots a kwestun 4 yous people
thank you for that information... it will be useful not only to me, but a
friend of mine too.
one more question... on the case of the usage of the parity bit on
overflow...
JP PO == says it overflowed?
JP PE == says it didn't overflow?
or is it the other way around?
thank you again...
-Greg
On Thu, 5 Mar 1998, Dines Christy Justesen wrote:
>
> As usual from my favorite Z80 asm book :
>
> P/V : Parity or overflow flag. Parity (P) and overflow (V) shere the same
> flag. Logical operations affect this flag with the parity of the result
> while arithmetic operations affect this flag with the overflow result.
> ... If P/V holds overflow, P/V = 1 if the result of the operation produced
> on overflow.
>
> So the Z80 has got a way to detect overflows. JR does not support this
> flag, but JP does, so you can just use JP PO and JP PE to check for
> overflows.
>
> Dines
> -----Original Message-----
> From: Greg R Milewski <l0rdg0at@juno.com>
> To: assembly-82@lists.ticalc.org <assembly-82@lists.ticalc.org>
> Date: 3. marts 1998 03:10
> Subject: A82: i gots a kwestun 4 yous people
>
>
> >
> >is there any way to detect a register overflow (like "jr o, label") with
> >the z80? it could really help if there was an instruction... else, is
> >there a simple routine i can use?
> >
> >thanx,
> >-Greg
> >
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> _______________________________________
>
> Dines Justesen
> Email: dines@post1.com or
> c958362@student.dtu.dk
> WWW : http://www.gbar.dtu.dk/~c958362/
> _______________________________________
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