Re: A86: Flags
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Re: A86: Flags
David Phillips wrote:
> I decided to my first real dissassembly of the rom. If this info is
> anywhere else (I'm sure it is, please point me to it):
>
> -IY+$1E ($C403) changes between $40 and $00--bit 7--somewhere in the
> keypress code. I can't find any instruction that does either res
> 7,(IY+$1e) or set 7,(IY+$1e). Do bits actually start at 0 when you are
> figuring the opcode (i.e. $46+8*b or $C6+8*b)?
> -$01ee is the start of the check for keys being pressed. It returns at
> $0220 if no key is pressed, at $0226 if one is.
> -$0229 is called to read the key port.
> -It uses four nop's in between it's in and out--does this mean progs should
> use 4 nop's when reading the key port instead of a halt?
>
> I'm trying to figure out where it decides where to jump to when you press a
> key like 2nd+mode. Then I could dissassemble the mode code to find all the
> IY flags.
I don't know how that will help you find all the flags. Maybe,though, it will
help you to know that $40 is binary bit 6 set (not 7).
>
>
> At 11:26 AM 5/27/98 -0500, you wrote:
> >
> >Are there flags somehwere in IY land that control the floating point number
> >thing in the mode screen? Just about everything else seems to be
> >controllable, but i can't find anything about that. I'm making a mischief
> >program to teach myself about the interupt and about IY flags, it will lock
> >the calc in certain modes. If you can help me, thanx a lot.
> >
> >Robby Gutmann
> >gutmann@planet-connect.com
> >ICQ UIN: 724927 Agonostis on IRC
> >
> >Of course, Ankh-Morpork's citizens had always claimed that the river water
> >was incredibly pure. Any water that had passed through so many kidneys,
> >they reasoned, had to be very pure indeed.
> > -- (Terry Pratchett, Sourcery)
> >
> >
>
> // David Phillips
> // mailto:electrum@tfs.net
> // AIM: electrum32
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