On Mon, Mar 23, 2020 at 11:29 AM Timothe Litt <l...@ieee.org> wrote: > The KL10 was the first microcoded machine. >
The first DEC microcoded 36-bit computer, but _not_ the first DEC microcoded computer! The PDP-9 (1966, core rope memory for control store), PDP-11/05 (1972), PDP-11/40 (1973), and PDP-11/45 (1973)) were all microcoded and predate the KL10. I'm not sure whether the PDP-15 (1970) was microcoded or hardwired. Some PDP-16 systems, including the PDP-16/M (1972), were microcoded. Since the KL10 was DEC's biggest, most expensive machine at the time, it wasn't nearly as cost sensitive as their other CPUs, so there probably wasn't even any consideration given to using PROM for the control store. I don't think you could have found fast enough PROMs. The KL is an ECL machine. There were ECL PROMs that were fast enough.
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