Speaking of 6502s, was Re: 70's micros still available - was 1802 problems

Chuck Guzis cclist at sydex.com
Tue Jan 3 12:43:08 CST 2006


On 1/3/2006 at 12:42 PM Roy J. Tellason wrote:

>Any of you guys have advice on how to get a grip on the weirdnesses of
>these chips,  when what I'm used to is 8080/8085/z80 assembler?

With the 6502, the big lmitation to me was the very small fixed stack (with
no overlow-underflow traps) and the heavy reliance on "direct" low memory
cells.  No 16 bit operations per se and almost everything you do affects
the condition codes.  You tend to think about everything in terms of 8
bits, even computing addresses.   Things that involve more than byte
quantities tend to get very wordy--for example, try writing a subroutine to
move an arbitrary number (up to 65K) bytes and compare it with the same in
Z80 or even 8080 code.  To me, the 6502 has more of a microcontroller
instruction set than the 8080/Z80. 

Cheers,
Chuck






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