On Mon, Feb 8, 2016 at 1:04 PM, Guy Sotomayor <g...@shiresoft.com> wrote:
> > > On Feb 8, 2016, at 12:43 PM, Noel Chiappa <j...@mercury.lcs.mit.edu> > wrote: > > > >> 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 > issue. > > The reality (unfortunately) is that no matter what solution I take, it’s > not > 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 > some > 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 > the > 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 > (they > > did exist BITD, I worked with a table-top one), but for them, an > additional > > 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 > cable > > or two to connect across (I dunno how extensive the interconnect > requirements > > 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 > has > 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 > that’s > 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 There is an old Vulcan saying: "Only Nixon could go to China."
