"Max Eskin" <maxeskin(a)hotmail.com> wrote: What on earth makes you think that you could build an x86 CPU with PII performance out of discrete transistors? It would be very difficult to get even the performance of a 286 out of discrete transistors. The discrete stuff tends to be *MUCH* slower than ICs. For reference, the IBM 7030 (Stretch) had one of the most complex CPUs ever constructed out of discrete transistors; it contained about 169,000 of them. Mind you, that's *only* the CPU; it doesn't include the memory controller, Exchange (I/O channels), Disk Synchronizer, or anything else. That's within an order of magnitude of most of the microprocessors used in today's desktop computers, and even closer if you make it a fair comparison by not counting the transistors that implement the on-chip cache memory. In fact, that's more transistors than a 286 CPU had (*), but AFAIK the 286 had several times more raw CPU performance than the Stretch. The overall packaging density of the Stretch CPU was approximately 0.06 transistors per cubic inch. The power supplies, fans, mounting frames, backplanes, cables, cabinets, etc. take up a lot more room than the transistors. Cheers, Eric (*) Intel's web site claims that the 286 had 134,000 transistors: http://www.intel.com/pressroom/archive/backgrnd/CN71898A.HTM They also make the completely ridiculous and untrue claim that the 286 was the first microprocessor that offered software compatability with its predecessors. To the best of my knowledge, the Intel 4040 was the first microprocessor to do so, and many others did this as well before the 286 was introduced, such as the Z-80, 8085 and 6802. Perhaps next year the government will declassify the 2nd-generation version of the F-14 computer, so that we can argue about whether it was the first backward-compatible microprocessor. :-)