Date   : Tue, 19 Jul 1994 18:11:09 +0100 (BST)
From   : clr1@...
Subject: Progress Report and some questions...

Well folks... I've very nearly emulated the whole 6502 instruction set in 
assembler. Only about 10 instructions to do, and I don't really 
understand them. At the moment I have a feeling that the whole thing is 
pretty buggy but I'll hopefully iron them out in the end.

I used the CBW branching method (b4 I read the postings about it 
actually; I was mailed by Richard Russell suggesting it) and thanks to 
everyone who helped me on that one. I now have the 256^3 loop executing 
in 47 seconds - 3 seconds off my beeb - on my dx/40. So near! I've also 
managed to allocate 64 contiguous K thanks to Stu Anderson's suggestions. 
Again, thanks everyone.

Anyway, here come my questions and I'm pretty stumped with 'em. Please 
help if you can...

1. What is the V flag for? Is it user-definable and that's it?

2. What does BIT do?

3. WHy have a direction flag, seeing as no operations I can see are 
direcitonal?

4. (PC question) does, for example, mov AX,[DS:SI] use up fewer clock 
cycles than mov AX,[DS:SI]+1? I've looked in my TASM manual but I'm 
buggered if I can follow it...

5. What do PHP/PLP do?

6. What does RTI do?

Thanks for the help in advance...

+-------------------+-------------------------------------------------+
| /-- |_| /-- | (~  | "And the driving is like the driving of Jehu,   |
| \-- | | |   | _)  | the son of Nimshi, for he drives furiously."    |
+-------------------+-------------------- Second Book of Kings 9 v20 -+