The weird stuff I keep finding: 19 bit core memory?

Eric Smith spacewar at
Wed Oct 21 00:09:25 CDT 2020

On Tue, Oct 20, 2020 at 10:02 PM Chris Zach <cz at> wrote:

> Ok, so the MF10 would have been hooked up to a KI10.

The ME10 was the first core box for the PDP-10 memory bus that supported
22-bit addressing, and could be used on the KA10, KI10, or KL10 (with a
DMA20 memory bus interface, not available on DECSYSTEM-20 configurations).
It has a toggle switch to select 18-bit or 22-bit addressing. The later
core boxes (MF10, MG10, and MH10) also supported 18-bit and 22-bit

The MA10, MB10, and MD10 only supported 18-bit addressing, so typically
wouldn't have been used on the KI10 or KL10.

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