21 Dec
2001
21 Dec
'01
12:37 p.m.
The fact that the 6502 was a kinda striped-down
version of
the M6800, and was more efficient from a computing power
perspective, has convinced some people that the 6502 was
the first (and only 8-bit) RISC-processor.
Some truth in here.
If the MOS people had given the chip more on board
general
purpose registers (i.e. like zero-page memory on-chip) and if they
had truely done away with some more Motorola-like CISC
instructions, it would really have pulled it off as a true RISC-design.
As for speed reasons there would have been no difference.
Code length would have been the same (instead of a zero
page address, the second byte yould have been a register
number), and execution size also - The cycle the 6502
used to access the memory youl now have been used internal
to execute the instruction. The only gain would have been
a cycle where the CPU don't uses the bus.
No real advantage - for it'S design the 6502 is close to
the possible maximum in terms of efficent timeing.
Gruss
H.
--
VCF Europa 3.0 am 27./28. April 2002 in Muenchen
http://www.vcfe.org/