I'm not sure I follow what you've said. The 650x and 6800 preceded the 6809 by
quite some time. Do you mean the 6809 could have been put in place of the
68000?
Stroke for stroke, the 6502 would have outperformed the 6809 in the applications
where the 6502 performed very well. I doubt it would have looked like a
rehashed 6800 however. The 6502 pipeline and byte ordering gave it a
significant advantage over the MOT parts. However, I saw some things done with
the 6809 that might have performed better than on a 6502. One thing, however,
that gave the 65C02 of the mid-'80's an advantage, was that it was available in
much faster versions than the 6809. Moreover, it was easy to prove that, since
Rockwell made a 65C102 that used the same E and Q clock scheme that the 6809
used. A little rewiring on an adapter mezzanine, and you could run it in the
6809's environment. I had to do that once to justify the cost of the faster
memory. It wasn't close, however, as the faster 65C102 (which was, aside from
the clock, just a 65C02) was MUCH faster.
Dick
----- Original Message -----
From: "Sipke de Wal" <sipke_at_wxs.nl>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, May 04, 2001 4:53 PM
Subject: Re: How many transistors in the 6502 processor?
> To state my point more clearly........
>
> I did not say it was a 16-bit, I said it should have been a 16-bitter given
the
> fact that all the major players at the time wore working on or, already had
> a 16-bit design in the cooker. Even Motorola was working on the 68000
> already.
>
> The 6809 would have replaced the 6502 and the 6800 in a lot of computers
> if it would have been aviable sooner!
>
> Sipke de Wal
> ----------------------------------------------------------------------
> http://xgistor.ath.cx
> ----------------------------------------------------------------------
>
> ----- Original Message -----
> From: Richard Erlacher <edick_at_idcomm.com>
> To: <classiccmp_at_classiccmp.org>
> Sent: Friday, May 04, 2001 8:15 PM
> Subject: Re: How many transistors in the 6502 processor?
>
>
> > I believe calling the 6809 a 16-bit machine is exaggerating somewhat. It
had
> an
> > 8-bit ALU and an 8-bit data bus, and an 8-bit almost everything else. Even
> the
> > 6801 had instructions that would concatenate the A and B registers so a
single
> > instruction would operate on the pair, and the fact that the 680x series had
a
> > 16-bit index register was more of a hindrance than a help as far as
> performance
> > was concerned. The instruction set was very nice, though. Although the
> > "internal architecture" supported 16-bit operations somewhat, it's a bit of
a
> > reach to compare it with, say, the i8088, which, though I hate the segmented
> > effective address computation scheme, is, in fact, a 16-bit architecture, as
> it
> > has a 16-bit register SET, a 16-bit ALU, and 16-bit instructions that
operate
> on
> > 16-bit operands.
> >
> > The 6502 had advantages over the MOT-style processors primarily BECAUSE of
its
> > 8-bit index registers. Because the index registers were a single byte, the
> > state machine that controls the physical address computation doesn't have to
> > decide to skip a cycle when the MS byte of the index is zero, nor does it
have
> > to decide what else to do with the upper byte, since there isn't one. Its
> 8-bit
> > character is what makes it faster than the MOT equivalents. It does 8-bit
> > things VERY fast, so long as they are scoped into table sizes easily
handlled
> > with the 8-bit index registers. Any 4 or 8 bit processor can process 16-bit
> > data, given enough time and resources. Some do it more elegantly than
others,
> > and I freely admit that the 6809 does it more elegantly. It just doesn't do
> the
> > 8-bit stuff as fast as the 650x family.
> >
> > The fact is, the 650x family was a smaller chip than the MOT, Intel, or
Zilog
> > parts of the same class. That suggests it had fewer transistors, since the
> > number of transistors would increase the chip size. Keep in mind, when
> > considering this contrast, that the 650x's general purpose registers could
be
> > viewed to reside in the "zero-page" since the access to that region was
faster
> > than to the rest of memory. Having larger registers and more of them, as
did
> > the 8080 and Z80 certainly would make the chip larger and the transistor
count
> > larger.
> >
> > It has a pipelined data bus, which, in reality, is just double-buffer for
the
> > benefit of the instruction decoder, so it can decode the opcode WHILE the
> > opcode's first operand, or the next opcode, is being fetched. While this
> > doesn't speed up an opcode's execution in a test setting, it does speed up a
> > sequential execution as you encounter when running code. If you look at
what
> > appears on the 6502's pins as it executes various instructions, you'll see
> that.
> > (this is documented in MOS Technology's 6500-Series Hardware Manual, so you
> > don't have to dig out the logic analyzer.)
> >
> > Dick
> >
> > ----- Original Message -----
> > From: "Eric Chomko" <chomko_at_greenbelt.com>
> > To: <classiccmp_at_classiccmp.org>
> > Sent: Friday, May 04, 2001 10:59 AM
> > Subject: Re: How many transistors in the 6502 processor?
> >
> >
> > > 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 - 20:30:35 BST