[A83] Re: tst + tstio instructions
[Prev][Next][Index][Thread]
[A83] Re: tst + tstio instructions
I didn't sign up for no support, and I downloaded the manual PDF from zilog's
site. I just selected the processor in the 83 Plus (hmm, z840000c or something)
and on the info page were the manuals in pdf downloadable.
--Peter-Martijn
>
>
> Hmm, you can get it from www.zilog.com under the techincal support area, but
> you have to sign up for a support account and give them the name of your
> dog. There's docs on ticalc.org under www.ticalc.org/pub/text/z80 but
> beware, some of them contain errors (mostly in the tstate counts). There are
> several that list the flags affected by each instruction in a nice format.
>
> -----Original Message-----
> From: assembly-83-bounce@lists.ticalc.org
> [mailto:assembly-83-bounce@lists.ticalc.org]On Behalf Of Ronald Teune
> Sent: Friday, July 06, 2001 9:25 AM
> To: assembly-83@lists.ticalc.org
> Subject: [A83] Re: tst + tstio instructions
>
>
>
> Do you have a specific address of where to get the docs?
>
> >The statements about the P/M flag are mostly correct -- however not all
> >instructions affect the P/M flag. Refer to the Zilog docs to see which do
> >and which don't. Carry isn't always affected either. For example, INC r and
> >DEC r don't affect the carry, even though there was a carry during the
> >operation. Again, the Zilog docs list how all instructions affect the
> flags.
> >
> >-----Original Message-----
> >From: assembly-83-bounce@lists.ticalc.org
> >[mailto:assembly-83-bounce@lists.ticalc.org]On Behalf Of Tijl Coosemans
> >Sent: Tuesday, July 03, 2001 2:15 PM
> >To: assembly-83@lists.ticalc.org
> >Subject: [A83] Re: tst + tstio instructions
> >
> >
> >
> >The P/M flag has the same value as bit 7 of A. If it's set (negative
> result)
> >then the P/M flag is set, and you test that with M. If it isn't set
> >(positive result) then the P/M flag isn't set (how obvious :-) and you test
> >that with P.
> >
> >The carry you can see as the 9th bit of A. When A overflows (larger than
> >$FF) then the carry is set. When the result is below 0 then the carry is
> set
> >either. Remember your first math classes. Then you had things like this
> (but
> >now in binary)
> >
> >ca 7 6 5 4 3 2 1 0
> > 0 1 1 1 1 1 1 1 1
> >+ 0 0 0 0 0 0 0 1
> >------------------
> > 1 0 0 0 0 0 0 0 0
> >
> >ca 7 6 5 4 3 2 1 0
> > 0 0 0 0 0 0 0 0 0
> >- 0 0 0 0 0 0 0 1
> >------------------
> > 1 1 1 1 1 1 1 1 1
> >
> >You see, the carry is set when a bit has been 'carried' over.
> >
> >In rotations and shifts, the carry has the same value as the bit that was
> >shifted away, carried away.
> >
> >Tijl Coosemans
> >
> >
> >
>
>
>
>
References: