On 1/12/19 1:13 PM, Jerry Weiss wrote: > On 1/12/19 11:39 AM, Bill Gunshannon via cctalk wrote: >> On 1/12/19 12:29 PM, Pete Turnbull via cctalk wrote: >>> On 12/01/2019 01:24, Zane Healy via cctalk wrote: >>> >>>> I’m pretty sure you could get the /23+, /53, /73, /83, and /93 in >>>> either a BA23 or a BA123. I have an actual badged BA23 pedestal for >>>> my /23+. >>> I'm fairly certain all microPDP-11/23+ systems were only sold in BA23 >>> boxes, and I think microPDP-11/73 and the later, cheaper, cut-down 11/53 >>> were as well. But almost all the 11/83 systems I've ever seen were in >>> BA123 boxes, though they did sell some in BA23 pedestals - I've got one. >>> >> One confusing part of this. Everything I have read today >> seems to say that the only difference between the 11/73 >> and the 11/83 in a MicroPDP-11 was the memory used. >> QBUS = 11/73 >> PMI = 11/83 >> > I use this guide in general - > http://web.frainresearch.org:8080/projects/pdp-11/dcj11.php to > understand the key differences in DEC DCJ11 implementations. You can see > how the clock speed, caching and memory type drove differences in > performance and marketing labels. > > The 11/83 (M8190-AD or AE) with Non-PMI memory is just a slow 11/83 in > my view. I know RT11 did report it as an 11/73. It could be that from > a software perspective, RT11 might not be possible to determine the > actual module in use.
I always thought it was an 11/73. It wasn't until the last few days that I saw the difference mentioned. It works fine as an 11/73 and having PMI memory and making it an 11/83 would just be for fun anyway. I have run Ultrix-11 on 11/73's with no real problems. > > Does the 2MB 11/93 not work with and extra 2Mb of QBUS Non-PMI memory? > I would have thought the upper 2MB would still be addressable, if for > nothing else than for compatibility memory mapped display controllers > and such. I had tried it and, no, it didn't work. I then had people tell me it wouldn't. I have also been told the only way to upgrade is to add the missing memory onto the CPU board. I find that hard to believe, but I suppose it is possible. I am not sure I could do that upgrade as some of the chips are surface mount. Not that it matters as a search could not turn up any supply for those particular memory chips. But, if I came up with a 2 meg or pair of 1 meg PMI boards I would definitely try it. :-) Just like the 11/73|11/83 deal. If a 4 meg PMI card fell in my lap I would definitely try it to see if there was a difference. Matter of fact, I would likely find some benchmarks I could run under Ultrix-11 and see what the actual difference was. But, it's all academic cause I really don't see any PMI memory falling from the sky and I haven't seen any pigs fly by lately. :-) bill