[A83] rst 20h crap
[Prev][Next][Index][Thread]
[A83] rst 20h crap
I found out something weird. rst 20h (TI-83-) is the
same as op1=(hl). So far so good. And rst 20h is the
same as call 20h. The next rst is rst 28h, so there
are eight bytes with possible code which is executed
with rst 20h. At 20h there is: EDB0C90000... , which
is ldir/ret. If you follow so far, rst 20h should then
be the same as ldir and the same as op1=(hl).
But this is not!
for ldir, bc is how many bytes, hl is from where to
copy to the addres in bc, so bc would have to be eight
(like eight bytes with possible code in rst 20h) and
de would point to op1 so that whenever you execute
ldir, everything would be set to that to copy the
following bytes at (hl) to op1.
But no!!
What the hell this is about????
If I think this way everything should match (like replacing stuff)
But have I made an error??
Here a prmg that uses rst 20h:
ld hl,name
rst 20h
call _chkfindsym
ret nc
jp _getkey
;when the prgm AWELCOME exists, and is not protected
;Done is displayed, otherwise it waits for a key input.
name: .db 5,"AWELCOME",0
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp