Date : Mon, 06 Mar 2006 22:38:32 +0000
From : Fragula <fragula@...>
Subject: Re: Warning: Sad case on list!
Jonathan Graham Harston wrote:
> Oo! Wow! A real PDP-11.
Well. its a Micro-PDP11/23, its a little "deskside" with 10 serial ports
(w. beeb compatible cables :-) and a VT320/
A *real* pdp-11 (note case here) would in my mind be an 11/70 fully
loaded except the "MMU" upgrade (can't remember what that was called)
with an ASR-33 w.punch/reader, some VT-52 and VT-100's (which I do
have!) twin dectapes and a couple of 9-tracks for luck. Mine is a nice
little thing though, and runs on single phase. It's operationalish<tm>
has some flakey RAM, probably oxidisation, but its 512L of /very/ small,
and socketed, RAMS. ISTR there being 256off 2Kx8 chips each with
probably 18 pins or so, and ONE of those pins has an intermittent
connection. I Don't have a bus extender, and the RAM is in the centre of
the main cage, so its not easy to fiddle with the chips with it powered
up in memory test. to trigger/locate the fault. I'll probably pull the
chassis covers off and open the.. Ahhh. (moment of realisation!) I have
a spare backplane in the attic! :-D
You might be interested in
> http://mdfs.net/Software/PDP11 - PDP11 emulator, PDP11 assembler
> written in BBC BASIC, and - my piece de resistance, as yet
> uncompleted - BBC BASIC for the PDP11!
Yep. i've spotted these already.. Looking to convert mine from MicroRSX
to BSD at some point. It has temperamental RAM at the mo, and is of the
age the loom liked to catch fire occasinally.
> Thank you.
Your most welcome! Its something I vaguely thought about, but the
software looked way too complicated for me alone, and Phil B. didn't
bite when I was fishing. Possibly I was too subtle.
I've started working out a simplified, essentially updated clone of
the ACW SCSI adaptor (which works fine with anything that works with
standard ADFS).
This looks hopefull, and is (here I go again) fairly "pure", but I ran
out of steam the last time I had to rearrange the house to fit more
stuff and children in. Lost my original hand drawn diagram now. So I'd
consider it years away. But at least there is no software requirement.
Also someplace I have a list of mid 90s drives that have resizable
sectors, and a couple of resizable Micropolis 5.25" drives. These are a
LOT quieter than the standard Acron ST-225, but I doubt as reliable (I
have four ST-225s, all working, and two were running 24/7 for four years
on a BBS. "Old ST-225's dont die, they just get noisier!" (and stiction,
but thats fixable.)
However i'll probably be contacting you for an IDE board fairly soon
anyway. Have to read up properly on your website, as i'm not too sure
what (apart from sector size) what the peculiarities are, study the
diagrams, whether there is any mileage on a 16 bit board over an 8 bit.
Whether you got the address decoding right, ;-> and how this will fit in
on a fairly busy 1MHz bus (a buffered "eurocard" type box of some sort,
on the end of a long "wedge feeder" cable, is probably where I'm going
to end up.
> You've got an FDFS?!? A SJ Reserch Floppy Disk File Server?
I'm kinda long-term custodian of one. I've certainly got it, but I don't
feel I own it, and I wouldn't want to part company with it.
> Don't ever throw it away! Any chance of pictures, disk images,
> documentation, etc?
Wouldn't ever dream of it.
If it ever upset me, which I don't think is that plausible, I would only
reprimand it gently, and pass it back to its previous keeper. It's a
very lovable little box. Silent and Solid, does what it says on the box
most of the time. The rest I blame on my rather flakey improvised clock
thingy - a model B with the user VIA timer free running and feeding a
driver IC.
Though the boot drive (half of a seperate Opus twin 40/80 unit) seems to
have gone into flake mode since I moved it gently downstairs to the
bench the weekend before last. I have a box of drives in the attic, but
its only alignment I'm fairly sure, so i'll have a crack at that. Done
'em before, do 'em again.
I can take pics soon, clothed an unclothed, its "on the bench" at the
mo, Nothing wrong with it, I'm just working on 3 beebs and a bunch of
copros there at the mo, and am hoping to do all the network reconfig
there as well. Its going to be two B's and the ACW, plus the FDFS, small
and simple. Then before putting it back in the server cupboard, I will
be changing the battery on the FDFS (if it has one, checking and
de-dusting the interior anyway if it doesnt) so I hereby promise a good
photo set!
Actually I might stuff the board(s) in the scanner as well if it comes
out easy. That's good insurance in case of "internal smoke damage" at
some later date, and the scans might be handy to someone else in that
situation too.
Disk images might be more complicated, which just means it might take a
little longer. I'll have to check over for passwords and personal stuff
that might be on there. I have a disk which I think is probably clean,
but isn't a write protected original. I'll check carefully first.
On the bright side I was presented with a Brand Spanking New YE-Data
5.25" Varispeed drive in work on Friday it was purchased in a machine
back in 1991, removed unused to make room for an extra SCSI hard drive.
Boxed up and put in a cupboard. I mentioned that one of my drives in the
house was playing up, and 10 mins later someone turned up at my office
with it! :-) its in son#3's windows box with Omniflop, and so far has
been 100% successfull, this thing will turn out great images.
As far as documentation is concerned, I only have a small leaflet type
thing with basic instructions, notes I made myself, and an ancient Fido
Netmail Somewhere<tm> from Phil (who is The Guru in these matters)
Don't get me wrong. I don't consider myself a collector really, just a
happy Acorn user, and I'd probably be even happier to hang the econet
off my big (and fairly quiet) Linux server in practice.
I've never used an MDFS, but guess it is very noisy, and the server room
is in a wall cupboard oppostite the "programming/office/darkroom area"
which is a little dressing room sorta annex with no door off my bedroom.
so noise is a major issue for me, and the FDFS is totally silent when
the disks are not being accessed.
Cheers!
M.