Path: utzoo!utgpu!watserv1!watmath!att!cbnewsh!rvp
From: rvp@cbnewsh.ATT.COM (rob.v.phillips)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Problem with AMAC
Summary: AMAC BUG?
Message-ID: <8724@cbnewsh.ATT.COM>
Date: 7 Mar 90 14:25:59 GMT
References: <53063@bbn.COM>
Organization: AT&T Bell Laboratories
Lines: 37

In article <53063@bbn.COM>, slackey@bbn.com (Stan Lackey) writes:
> I have been using AMAC quite a lot lately, and have determined that
> there is a bug in it.  
  ...
> If you know anything about this, you may be the one person that reads
> this that can help.  Please respond; 
> ...ANY help is greatly appreciated.  Even the most
> insignificant-seeming idea could save me a tremendous amount of time.
> 
OK! You opened the floodgates for insignificant-seeming ideas!
I, for one, believe that ANY news is GOOD news in SOME groups where the
traffic flow seems too low for my interests, so I'll throw in 2 cents!

First off, I have just a little experience on AMAC, so I can only
suggest that you may be encountering a rare but bad assumption
concerning 6502 programming in general. A book by "Leventhal" on
6502 Programming has a good section on "Common Programming Errors"
that I have found invaluable.
A couple of glimmers through the fog of my memory:
There is some problem with indirect jumps on the 6502 if the address
crosses a page boundary (specifically, it doesnt work right).
There is something unusual about the brk instruction... I think
it pushes the Program counter PLUS 2 on the stack, so you might need
to stuff in a nop or something after a break?
Another possiblity that I have encountered on other assemblers is that
they support the 6502c, and if you use 6502c instructions, they assemble
them OK, but your target CPU may not understand these and punt. 
One problem that troubled me for hours recently...perhaps a SYNTACTICAL
one! I said "TXS" where I meant TSX! That was tough to debug!

Finally, if you have the resources, and have not tried it, 
you could of course, check this code out on another assembler.
However, if any of my above statements is interesting and it inspires you
to broaden your vistas on 6502 programming...why, your life will be
generally heightened! On the other hand, if any of my statements is
false (I do not attest to these), perhapse more responses on the net
will heighten MY life! What a country!