Re: ti-emu: what exactly does the status of the Parity/Overflow flag mea
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Re: ti-emu: what exactly does the status of the Parity/Overflow flag mean?
>From: Liyang Hu <liyang@altavista.net>
>Reply-To: ti-emulator@lists.ticalc.org
>To: ti-emulator@lists.ticalc.org
>Subject: ti-emu: what exactly does the status of the Parity/Overflow flag
>mean?
>Date: Wed, 09 Jun 1999 10:59:16 +0100
>
>
>(this list is awfully quiet...)
>hello all!
>i wasn wondering if anyone here could help me.
>i'm trying to do a little emulator project here, but i can;t figure out
>what the parity/overflow flag on the z80 is supposed to do: afaict, it
>toggles between P and V (according to the z80 docs i've got). What does P
>and V stand for?
>
P means Parity, and V means Overflow. They are the symbol representations.
Now, as to what they MEAN, Parity is set if the result of an operation such
as SAR results in an even number of set bits. Overflow is set if the result
of an operation such as ADD results in a value which overflowed into the
sign bit. Such as adding 1 to 0x7FFF (32767), which returns 0x8000
(-32768).
>btw: please dont tell me to buy a book or something, as i'm completely
>broke and can't afford anything right now.
>
At www.zilog.com you can actually get the documentation for the Z180 online,
(the Z180 is just a Z80 with extra stuff, once you learn which are extra,
you can ignore them) this documentation will explain what every opcode does,
what flag it effects, and give examples.
>arigatoo and sayoonara!
>denseboy
Hai, dou itashimashite
Daniel
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