12 Jan
2019
12 Jan
'19
10:23 a.m.
On 1/12/19 1:13 PM, Jerry Weiss wrote:
On 1/12/19 11:39 AM, Bill Gunshannon via cctalk
wrote:
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.
On 1/12/19 12:29 PM, Pete Turnbull via cctalk
wrote:
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. On 12/01/2019 01:24, Zane Healy via cctalk
wrote:
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?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.
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