On 08/09/2016 00:37, Glen Slick wrote:
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.
Too big. They're a pair of 8K ROMs, but the BDV11 only supports 2K and 1K devices.
Why are MRV11-D boards so expensive, at least on eBay? Were they sold in relatively low volume compared to CPU boards?
I guess that's the reason. I've only ever seen two, but I've seen (in fact I have) lots more earlier ROM boards and several MXV11-Bs. I suppose by the time the MRV11-D came out, people who needed a bootstrap paging capability either had 11/03 or 11/23 systems with BDV11s or, if they needed an 8K bootstrap, had microPDP-11s, in which the bootstrap is always on the CPU card. Almost anything else could use the cheaper MRV11-C (though it only supports up to 4K chips) and even that supports the conventional bootstrap mechanism, albeit only 16- or 18-bit, not using BBS7.
-- Pete Pete Turnbull
