> > According to the intel Web site an 8080 has about 6000 Transistors.
> > Now, it is possible to put up some 12 to 16 FF gates in discrete
> > logic (discrete non SMD transistors etc.) gates (~40 Transistors)
> > onto one Euro-Card board (I tid once build up 16 FFs on one board
> > - at the age of 16, I tried to miniaturize :). So, spreading 6000
> > transistors at 40 transistors per board gives some 150 boards.
> > And with an asumption of 20 boards per row we need some 8 rows,
> > or a small (half height) rack.
> With gating and interconnect it will grow.! Also that would be a CPU chip
> replacement... memory, IO and control pannel would be needed.
Well, the whole question was about a CPU chip replacement,
_not_ a working computer including maybe 64K of Mem.
> I think the key is yes it can be done. Yes with moden discretes and
> technology you can compress it. However the devil is heat and a SMD
> transisor at 10mW per is going to get hot with 40 per board! Why 10mW?
> You have to drive wires and other gates and these are not MOS devices like
> on the chip (you can but you still used real resistors) so things like
> fanout/fanin are considerations.
Well, I assumed _non_SMD - 10 mW per transistor isn't a wrong
asumption - also you should add some 50% more heat dispendes
by the needed resistors. So .6W per board sounds right - but
thats stil no big hassle. Using a proper rack, even 10W per
card can be handled without problems (with good airflow of
course).
> While there are small serial computers a look at them shows some things
> that need to be reflected upon. They were serial archetectures and
> minimized the used of things like registers as they were hardware
> intensive. The Minuteman Missle computer I"d played with many eons ago
> was such an example. Flipflops were very scarce in that machine.
Jep, but using a way different architecture than the original
CPU would again miss the design goal (at least in my opinion).
In fact, I've meditated over a similar question several times:
Wouldn't it be great to have 3 C64 at display (in a museum) with
3 different incarnations of a 6502(6510) - one with the 'real'
chip, one with a TTL replacement on lets say one board (like
Dicks wire wrap) and the third utilizeing a big box with transistors.
(And before y'all argue about backdraws, of course I know that
it is close to imposssible to get the TTL running at 1 MHz inside
the NMOS specs, but that can be solved by lowering the CPU clock
and selecting an aprobiate Application :)
I just belive this would give a _great_ display - unlike all
these dump displays where they put a sack of transistors beside
a uP and tell you just that they are equivalent.
Anyway
Gruss
H.
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Ich denke, also bin ich, also gut
HRK
Received on Wed Oct 20 1999 - 12:19:47 BST