22 Jun
2013
22 Jun
'13
6:49 a.m.
From: Pontus: Saturday, June 22, 2013 3:33 AM
On 06/21/2013 07:19 PM, David Gesswein wrote:
I think we're all "right", depending on which gizmo we are describing :-).
The bare PDP-8/L has a maximum of 4K.
The BA08 adds 4K for a maximum of 8K.
The BM08 adds up to 8K for a maximum of 12K. (According to the OS/8 support
manual, it actually inhibits CDF instructions for fields >2, treating them
as a NOP.)
The BM8L adds up to 28K for a maximum of 32K. (It extends the IF and DF to the
full 3 bits, so I'm quite sure it goes beyond 16K.)
At most one of the memory expansions is permitted, since they conflict about
their
implementation of the extended memory control.
Since the expansion boxes seem to have been introduced at various times,
documentation for the PDP-8/L differs about whether 8K or 12K is the
maximum. The BM8L is fairly rare. I think it was introduced near the end
of the life of the 8/L, and I don't think I've ever even seen it discussed
in an
8/L manual.
Unfortunately, little to no actual BM08 documentation seems to exist any more.
I have the BM8L print-set somewhere in dead-tree form. Drawings are around
on the net for much of the BA08, but are spread around in the descriptions of
various options (for example, the MC8L).
Vince
On Fri, Jun 21, 2013 at 04:03:57PM +0200, Philipp
Hachtmann wrote:
According to Vince, you can go all the way up to 32kW with the BM8L:
http://so-much-stuff.com/pdp8/8L/8L.php
I don't know who is right :) But it's all difficult with this machine. And
8K
memory (with 4K in a separate 8/L expansion box) is the maximum you
can attach.
Actually you can get up to 12k with the BM08 box. I have one but haven't
found any documentation for it yet. The BM08 has one more set ot switches
and a light on the front for the extra IF/DF bit you need.