27 Feb
2002
27 Feb
'02
7:46 p.m.
--- "Zane H. Healy" <healyzh(a)aracnet.com> wrote:
If it's a BA-11N, it _has_ BDAL16 and BDAL17 bussed.
If money is no object or people are throwing hardware at you for free,
I would agree... for long-term maintanability, I'd endorse SCSI, too.
Wish a CMD controller would drop in my lap.
It did have the
M8186 11/23 CPU in the 11/03 chassis when I got it...
My guess is that the chassis has either got a different or upgraded
backplane. Is there any kind of a number on the backplane itself
that
you can easily see?
That would be best for ident purposes.
OTOH, maybe I'm misremembering and a Q18 CPU will
work in a Q16
backplane.
It will, but only to 28KW.
...Lacking the
funding to develop something new...
Something else you might want to look for is an
ESDI controller. It
would allow you to use slightly more reliable disks, though SCSI is the
best. The important thing is to stay away from MFM disks!
Here, I have to disagree. Depending on the nature of the project, it
might be just fine. If you don't need more than about 80Mb of total
disk space, or if you are graduting up from floppies and even 20Mb seems
large, MFM is fine. If you have, as was mentioned, lack of budgetary
support, an MFM controller, like a DEC RQDX[123] and an ST225 is about
the cheapest solution I know of - drives and controllers are available
for haul-it-away prices. No, the MFM drives aren't going to last forever,
but for the cost, a second drive is no big deal, either. True, a 3.5"
SCSI drive of low (sub-1GB) capacity is also a "haul-it-away" item, but
the controller sure isn't.
Abstractly speaking, if the need to run MSCP isn't an issue and cost is,
MFM may be the best way to go for any PDP-11 project. Personally, where
it falls short for me is wanting to play with PDP-11 UNIX - to go with
an MSCP controller, recent patches aside, MSCP requires 2.11BSD and a Split
I&D processor unless I've misremembered something. If I'm going to play
with 2.11BSD, I want a disk larger than an ST-225 (RD31) or even a
Maxtor XT2190 (RD54) - I'd like to have a couple-hundred meg so I don't
feel like I have to scrub the disk of logfiles every few hours. I've
installed 2.9BSD on an 11/24 with 2xRL02. It was a tight fit and I
don't think there was room for sources and to rebuild to kernel without
deleting lots of stuff first.
I'm just saying that MFM drives aren't always the wrong answer on a
PDP-11... it depends on what your criteria are.
-ethan
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