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
> ----------------------------------------------------------------------
> http://xgistor.ath.cx
> -----------------------------------------------------------------------
>
> ----- Original Message -----
> From: ajp166 <ajp166_at_bellatlantic.net>
> To: <classiccmp_at_classiccmp.org>
> Sent: Friday, May 04, 2001 1:03 PM
> Subject: Re: How many transistors in the 6502 processor?
>
> > From: Brian Chase <bdc_at_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
> >
> >
Received on Fri May 04 2001 - 11:59:56 BST