On Wed, Oct 21, 2020 at 6:22 AM Pontus Pihlgren via cctalk < [email protected]> wrote:
> On Tue, Oct 20, 2020 at 11:26:22PM -0400, Chris Zach via cctalk wrote: > > > Or maybe a PDP-15? 18 bits plus parity. > > > > Possible, did the pdp15 use that type of board? > > > > I have seen PDP-15 core memory and it is not that format. It looks like > the memory modules from a PDP-8/I or -8/L > The ME15 memory for the PDP-15 used that kind of memory, but it normally used an 18-bit H215. I think there was another variant that offered parity that would have used the 19-bit H216. There might have been PDP-15 memory earlier than the ME15, but at the time of the PDP-15 introduction (1970), H21x core planes were used in most DEC machines, so it would have been surprising for them to use something else. Perhaps some PDP-15 systems were upgrades from the PDP-9, which used memory modules similar to the PDP-8/I.
