7 May
2014
7 May
'14
5:44 p.m.
On May 7, 2014, at 3:57 PM, Eric Smith <spacewar at gmail.com> wrote:
> The KW20 was not used on core-based systems, and
was introduced with the
> MF20 semiconductor memory, so the drawings for the KW20 master oscillator
> are in the MF20 and MG20 print sets, which are on Bitsavers.
On Wed, May 7, 2014 at 5:20 PM, Guy Sotomayor <ggs at shiresoft.com> wrote:
I've been through the print sets and all I've
found is the block diagrams.
If you can
point me to the specific doc then I'll look for it there.
From either MP00622_MF20_Oct82.pdf or
MP01904_MG20_Jun84.pdf, pages 9
through 12 of PDF files:
D-DD-5412851-0 Rev B: Drawing Directory, Master Oscillator
D-UA-5412851-0-0 Rev D: Unit Assembly, Master Oscillator
D-CS-5412851-0-OSC1 Rev A: Circuit Schematic, Master Oscillator Select Logic
D-CS-5412851-0-OSC2 Rev B: Circuit Schematic, Master Oscillator Power Supply
> The Xbus cabling looks similar
> to VAX SBI cabling. I'm pretty sure you got at least one M8572/cable
> assembly from me, when we were scrounging for missing parts.
Yes, I have that assembly. That was critical too. But I think there are
other
cases where the S-Bus is used and I need the cables for that. As I recall
the
other uses don't involve talking to memory (I/O?).
Nope. Sbus and Xbus don't do anything other than talk to to memory, Sbus
to MA20/MB20 core or DMA20 external KI memory bus, and Xbus to MF20/MG20
semiconductor. The only thing that they do when talking to memory boxes
that isn't actually a memory access is read/write of the memory controller
diagnostic registers. In a system with external (Ibus) memory, which is
never used on a 20xx, one Sbus (slot 3) is jumpered to slot 3 of the DMA20
memory interface.
Everything else is over the Cbus (channel) and Ebus (internal I/O), from
slot 1 of CPU backplane to slot 37 of RH20/DTE20 backplane. In a system
with a DIA20/DIB20 external I/O adapter adapter, the Cbus and Ebus are
jumpered from slot 1 of the RH20/DTE20 backplane to the DIB20 or
DIA20/DMA20 backplane.
The Cbus (slot 1CD and 1EF) does use BC20C cables to the RH20/DTE20, but
it's not Sbus.
There's a drawing of the BC20C in MP00300_KL10ErevM_Feb83.pdf on pages
182-183, but it doesn't give a schematic.