Forwarded message:
Date: Thu, 9 Oct 1997 02:32:27 -0400 From: ghio@temp0133.myriad.ml.org (Matthew Ghio) Subject: Re: 6502 ML programming
Jim Choate <ravage@ssz.com> wrote:
There in no 'DATA' construct in 6502 assembly.
This is some sort of macro that either the assembler or programmer defined. All official Rockwell/Commodore [1] 6502 assembly mnemonics are three letter.
True, but most assemblers would let you insert static data into the object file using various pseudo-ops like that.
Idealy a jump table was created that had the various target addresses for your routines.
Oh, those were fun to debug too...
The most efficient way to store data in 6502 is to put it in the first 256 bytes of ram, then it could be called in no more than 2 clock cycles.
Actually that took three cycles. One to fetch the opcode, one to fetch the target address, and one to fetch the data byte. If you wanted to do it in two cycles, you had to write the data into the operand of the instruction that loaded it (self-modifying code).
Wow, we actualy agree on all points...that has to be a first. ____________________________________________________________________ | | | The financial policy of the welfare state requires that there | | be no way for the owners of wealth to protect themselves. | | | | -Alan Greenspan- | | | | _____ The Armadillo Group | | ,::////;::-. Austin, Tx. USA | | /:'///// ``::>/|/ http:// www.ssz.com/ | | .', |||| `/( e\ | | -====~~mm-'`-```-mm --'- Jim Choate | | ravage@ssz.com | | 512-451-7087 | |____________________________________________________________________|