19 Oct
1999
19 Oct
'99
6 p.m.
Say someone were to home-build a CPU from scratch
using only individual
components, no ICs only modern descrete(?) components. How big would the
CPU be? For comparison lets say it would be an 8080 clone. Any guesses?
One of the vendors of bit-slice components (AMD 2900 or clone, I think)
offered a board that emulated an 8080. In addition to being faster than
an 8080, you could of course modify the microcode to add or change
instructions. IIRC, it looked like the board had about fifty chips.
If you didn't use a bit-slice, you'd have to use separate ALU, memory,
and shifter chips, and you'd wind up with even more.
The early microprocessor architectures were designed based on minimal
transistor count for a single-chip implementation. This does not result
in minimal chip count if you implement the equivalent in 7400-series
chips. It is quite possible to design useful processors with a lot fewer
TTL chips.