Ian S. King
isking at uw.edu
Mon Feb 8 15:08:52 CST 2016
On Mon, Feb 8, 2016 at 1:04 PM, Guy Sotomayor <ggs at shiresoft.com> wrote:
> > On Feb 8, 2016, at 12:43 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu>
> >> From: Guy Sotomayor
> >> I also wanted to get folk's opinion on the need to actually produce an
> >> S[P]C form factor board. ... is it OK to have the MEM11 be outside of
> >> the 11/20 chassis and connect via BC11A (my replica) cables?
> > Well, that's going to up the cost; for some people, that might be an
> The reality (unfortunately) is that no matter what solution I take, it’s
> going to be inexpensive. The reality is that an SPC board will be more
> expensive because of the gold edge fingers.
> The other thing is that the boards will be fully assembled. Except for
> connectors and the UNIBUS transceivers, everything else is surface mount.
> I’m still crossing my fingers that I can keep within the 208 pin PQFP for
> FPGA and not have to move into a BGA part.
> > Also, I dunno if there are people out there with table-top 11/15's-20's
> > did exist BITD, I worked with a table-top one), but for them, an
> > box might be a hassle too.
> >> That's assuming of course that the power requirements for the MEM11
> >> can be fulfilled by a single SPC slot. ... in the worst case, it may
> >> require splitting the MEM11 functionality across multiple boards.
> > I guess I don't see the harm in making it two SPC (quad) boards? A flat
> > or two to connect across (I dunno how extensive the interconnect
> > between the halves would be, and I have forgotten what the inter-slot
> > interconnect capabilities of an SPC backplane are - ISTR that it has some
> > bussing on the F section pins) would be easy and cheap.
> See above re: gold edge fingers. I was originally thinking that if I do
> have to
> split the board up, that I’d make them completely independent. But that
> the issue of requiring 2x the number of UNIBUS transceiver parts (which are
> all but unobtainium as of now). One of the things that drives up the
> power (and
> board area) are said transceivers (and level shifters, etc). If I could
> come up
> with a reasonable alternative for the SPC version, that may work. But
> all in the future at the moment.
> TTFN - Guy
A thought: would a second quad board necessarily need transceivers? I'm
thinking of the top-block connectors used in the PDP-8, and the top-plugged
ribbon cables for e.g., MicroVAX II CPU-to-memory connection. You might
still want to grab power through a few fingers, but that's an
implementation detail. -- Ian
Ian S. King, MSIS, MSCS, Ph.D. Candidate
The Information School <http://ischool.uw.edu>
Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical
Narrative Through a Design Lens
Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org>
Value Sensitive Design Research Lab <http://vsdesign.org>
University of Washington
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