4 May
2001
4 May
'01
4:48 a.m.
Please see remarks embedded below.
Dick
----- Original Message -----
From: <jpero(a)sympatico.ca>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, May 03, 2001 9:51 PM
Subject: Re: How many transistors in the 6502 processor?
Back in the mid-80's I built a 6502 equivalent circuit in STTL using
wire-wrap
and fit it on a nominally 5x8" wirewrap board with space remaining. I didn't
measure power, but that's not the issue. I didn't implement the extra adder
stages in the ALU to support the BCD-mode instructions, but otherwise the thing
seemed to execute the existing 6502 code adequately. This sort of thing is not
easy to verify in an APPLE environment because of the timing accomodations made
to support seamless integration into the NTSC video scheme.
I don't remember the scale on which the NMOS 6502 was built but it must have
been about 4-5 microns. In '85 they guys in the IC mfg industry were bragging
up their 2 micron process.
Date:
Fri, 4 May 2001 02:18:11 -0500
From: Brian Chase <bdc(a)world.std.com>
To: <classiccmp(a)classiccmp.org>
Subject: How many transistors in the 6502 processor?
Reply-to: classiccmp(a)classiccmp.org
And then it'd be rather fun to implement your very own 6502 using 74*
series logic chips.
Possible, but length of traces to wire all those together will keep
it to KHz range and needs few large boards that needs so much power
that hottest athlon cpu is low power by comparsion.
I have seen photos of apple IIe prototype laid out on early
pre-production logic board, one of that 40 pin chipset socket is
hooked to a equally same size board filled to the 4 edges with
tightly packed TTLs and few large ICs, I think it was shown in Byte
as well as few other publicatons. Large board full of chips vs. 40
pin IC, same thing...Amazing!
It's not a bad idea to remember that in '79, when HP was bragging up their
450k-transistor CPU that dissipated 7 watts, IBM was routinely making IC's with
1M transistors in packages about an inch square. They just didn't brag about
it.
Side effect to this, you get less power requirement and can speed up
whole thing and more rapid signals due to very short traces and
on-die itself.
That is why TTL-based microcomputers and mainframes has massive PSUs
even using switching technologies and mini-tunnel wind effect to cool
everything. While same computing power can be on one 4pin chip
microcontroller and run on 1 AA directly for hours even weeks under
hottest sun.
While some of the points made here are arguably correct, taken by themselves,
they don't wash in a real-world/real-history context.
Cheers,
Wizard