On Wed, Sep 7, 2016 at 3:59 PM, Pete Turnbull <p...@dunnington.plus.com> wrote: > > Yes, it has a lot of ROM sockets: it's a bootstrap/terminator/LTC card. In > fact it's the archetypal bootstrap card, the one that first had the paging > mechanisms all the others use. The problem is none of the sockets support > large ROMs, so there's a lot of fiddling to do to get a microPDP-11 > bootstrap and diagnostics in there. You have to split each ROM into four > devices, so eight in total. I'm well aware of how BBS7 works, but that's > not the issue. Unless the BDV11 is modified, it doesn't work correctly in a > 22-bit system as it has 18-bit termination. Although DEC listed the BDV11 > (Rev.F only) as compatible they classed 22-bit 11/73 systems using a BDV11 > of any sort as "not field serviceable" and wouldn't supply or support any > that way. >
http://www.bitsavers.org/pdf/dec/qbus/oemMicronotes.pdf uNOTE #004 LSI-11/73 Upgrade Paths "NOTE 1. In the following upgrade scenarios, the systems have been labeled as being Field Serviceable or not. A system which is Field Serviceable has a bootstrap which meets Field Service requirements. The requirement is that the bootstrap must execute an 11/73 cache memory diagnostic on power-up. There is not guarantee that the overall system will be Field Serviceable or that it will be FCC compliant." Basically this boils down to having the MXV11-B2 Boot ROMs installed on either an MXV11-B or MRV11-D. The MXV11-B2 Boot ROMs are apparently not compatible with the BDV11, for reasons I don't remember 100% off the top of my head. Why are MRV11-D boards so expensive, at least on eBay? Were they sold in relatively low volume compared to CPU boards?