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by cbm-vic-20 1810 days ago
The first-gen PDP-11's CPU was just a couple of boards full of good old TTL chips.
2 comments

Yes, the pdp-11/20, released in 1969. Core memory only. In my opinion, it took the pdp-11/45 to firmly establish an impressive new line of machines, separate and more powerful than the pdp-8 line. But, in DEC's way of thinking, it's instructive to note that a pdp-11/40 was used as the console of the DECsystem-20. Separately, it's a shame we no longer have 36-bit machines; 36-bit ints would hold time_t just fine, and 72-bit doubles will work great for science. Oh well. What we're stuck with now bytes.
I remember reading an old paper on some funky experimentat user-interface that used a pair of PDP-11s (possibly, might have been event older) essentially wired together at the busses, with extra instructions added with new logic in TTL silicon, I think it was for doing the maths for the vector graphics. It was amazing the amount of hardware hackery that was necessary to build these experimental systems.