4 May
2001
4 May
'01
4:59 a.m.
Sipke de Wal wrote:
With hindsight one can consider the 6502 to be the
only 8-bit RISC CPU
It had a reduced number of registers compared with the 6800 and this and
other logic-reduction simplified the design so it could execute code a lot
more efficiently as compared with the 6800. Also the 256-bytes Zero-page
could be regarded as an (extended) RISC-like registerset of the CPU.
Many looked at the zero-page and the 8 bit stack pointer as shortcomings.
It was the X and Y index registers both 8 bit, that made the chip interesting.
The X/Y pair made memory-madpped video graphics easier to implement.
I remember a magazine (BYTE?) describe the 6502 as a true RISC-chip
but I don't thing the designers had RISC-CISC philosofies in their heads
while working it out.
RISC per se didn't come out until the 80s.
Only 6809 bas a "better" chip but that should have been a true 16-bit design
It came way to late to make a large impact. Only the COCO used it in a
homecomputer.
The 6809 was fine as a 8 bit chip with a 16 bit internal architecture, and many
home computers used the 6809 CPU not just the CoCo.
SWPTC made one. The operating system OS/9 was built around that chip.
Viirtually every manufacturer of the SS-50 bus had a 6809-based system, and
that
would be around a half dozen.
The CoCo may be the most well known but not the only.
Eric
Sipke de Wal
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----- Original Message -----
From: ajp166 <ajp166(a)bellatlantic.net>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, May 04, 2001 1:03 PM
Subject: Re: How many transistors in the 6502 processor?
> From: Brian Chase <bdc(a)world.std.com>
>
> >Does anyone know how many transistors made up the 6502? These days with
> >Intel's boasting of the number of transistors their latest processors
> use,
> >it'd be interesting to know what we used to get by using. What, it
> can't
> >have been more than a few thousand, right?
>
>
> Memory says it was one of the lower transistor count cpus, very efficient
> design.
>
> >And then it'd be rather fun to implement your very own 6502 using 74*
> >series logic chips.
>
>
> I'd bet it would be fairly high chip count. IT would be interesting to
> see how fast
> you cound make it go.
>
> Allison
>
>