OT: how big would it be?

ok, By discrete you meand transistors and diodes. An 8080 cpu would likely fill a rack 20-25" high with boards. The memory would have to be core for practicality as a static FF cell uses lots of transistors and would be huge. using core 64k would likely fill one or more 6" racks (using 1967ish technology). A uart would fill a 9x11 board with TTL and that would expand to maybe 4-5 boards as transistors/diodes. A pdp-8 (early) had a pannel roughly 24"x50" with flip chip modules mostly transistors and the 4k core was a 10" tall rack section. for rough comparison. In many respects the 8080 is a far more complex CPU and would be significantly bigger. It would also be slow compared to the NMOS part. Doing it in ttl or bit slices would still be big, I've done that. using 2900 parts(ca mid to late '70s) the CPU equivelent was over 100 chips and filled 4 10x8" cards. Allison