23 Oct
2020
23 Oct
'20
12:35 p.m.
On Fri, Oct 23, 2020 at 11:57 AM Eric Smith <spacewar at gmail.com> wrote:
the
memory modules from a PDP-8/I or -8/L
The ME15 memory for the PDP-15 used that kind of memory [H215/H216], 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.
The PDP-15 print set on Bitsavers shows that the original PDP-15 memory was
the MM15, which was in fact very similar to the PDP-8/I memory, and was
available with or without parity.
The ME15 must have been developed for later PDP-15 systems, and used the
newer H215 core stack. I can't find any evidence of a parity version of
that, which if it existed would have used the H216.
On Wed, Oct 21, 2020 at 6:22 AM Pontus Pihlgren via
cctalk <
cctalk at classiccmp.org> wrote:
I have seen PDP-15 core memory and it is not that format. It looks like