22 Jul
2018
22 Jul
'18
11:36 p.m.
Studying the MS11 Maint Manual, the MS11 controller has access to the full
address and data from both the CPU (FastBus) and UNIBUS B. (The FastBus
actually has two uni-directional data busses; in and out.) So all that
info,
this hypothetical cache board can get from the slot it is plugged into
(assuming the cache is plugged into one of the controller slots), over its
connector pins.
The connectors on the back of the card, and two small boards, must be for
listening to UNIBUS A (in configurations in which the two UNIBI aren't
joined
together)? (I'm too lazy to check the slot numbers are see what they
actually
are.)
And there is indeed a signal which the MS11 uses to tell the CPU it has the
location the CPU is asking for, so it's theoretically possible to build a
cache
card that plugs into a FastBus slot.
Here is how it is connected: https://i.imgur.com/4TEZoiO.jpg
The sandwiched dual boards are i sitting in 27 / 26 AB. The board in 27AB
was empty (quick glance), while the board in 26AB has a few TTL chips on it.
Slot 26AB is the Unibus A slot, Slot 27 AB should be a terminator on
Unibus B. (maybe there were terminating resistors on the second board.
Didn't check in detail) Slot 28AB is Unibus B and goes to the DD11-C and
the RK11-D backplanes.
The hex ABLE/ ACT board sits in slot 21 which is the memory controller
board for the MS11.
It very much looks like it is a Cache board. But why have some one written
"Not used" (Anv?nds ej) on it? I'll hope I find the documentation for it!
/Mattis
Noel