Hexagon

[Bob Eager]

Very nice! I'm currently working on one for the ICL 2900....!

[Andrew Gabriel]

I have a 3.5" disk (100MB SCSI). I have taken off the lid and made a perspex one. The drive dates from when an SS (Self Seek) jumper was provided, which makes the head seek around in all sorts of interesting patterns for displaying on exhibition stands, without needing to connect up anything other than power (and could sometimes be used for testing the drive). Unfortunately, the self seek pattern on this drive (butterfly seeks) was not as wide a selection as some others I've seen, but it's still very interesting to people who haven't seen a drive operating before.

I have a 14" exchangable pack, like this one:

12 of the 20 surfaces are head-crashed. That was particularly expensive in the case of my disk as it was a head alignment pack, which cost megabucks (someone told me £30k at the time just for the head alignment pack, never mind cleaning up and replacing the drive heads). The alignment packs were called "CE" packs, because of the pattern they generate on the engineer's 'scope, which looks like alternating C and E characters laying on their backs.

I also have some 8" and 14" platters which had too many errors to be usable, but there were no visible marks on them (well, not before they were handed around a class of kids).

I give talks on computing, and these make for nice props for some audiences/topics.

[Bob Eager]

I'll have to look out for one of thise. Or wire one up to a PIC...

I always thought CE stood for Customer Engineer - but then I've not seen the waveform...

I teach computer science, and think it's valuable to cover a little bit of history. The replica I built will be used for that, a bit. At the end of my last lecture in one module I did demonstrate compiling and running a FORTRAN program on one of the 32K 12 bit PDP-8 replicas...

Next task...getting the PDP-11 (a real one) running...

[Tim S]

Bob Eager coughed up some electrons that declared:

Which one do you have? And does it come with the boot ROM or do you have to key in the loader?

My only touching of one was a PDP11/44 at Reading University (Dept of Engineering) in 88/89 - they had the ROM, but typing the loader commands and watching it boot (for 20-25 minutes!) was kinda cool for a 20 year old :)

[Bob Eager]

It's an 11/23 (that's the one with the CPU as up to four LSI chips). Boot ROM is there, because in fact it has a ROM monitor that does the work of the front panel (so no real switches, just a Boot/Halt one and a couple of others).

I have on occasion keyed in a bootstrap on an 11, but most of ours (we had several) had boot ROMs. But I can do it to my heart's content on the little PDP-8 replica (although it too has a ROM monitor that runs in a separate address space).

We'd lost most of ours by then, and the only one I used was the little PDP-11 used to control our VAX 8800 (you even powered the 8800 off and on with commands on the 11).

[Tim S]

Bob Eager coughed up some electrons that declared:

I was at York Uni late 80's, (Reading was a temp job mid degree). The 8550 and 8600 were loaded by MicroVaxen IIRC. Wasn't the HSC disk controller a bastardised PDP? I always had a bit of a laugh lookign at that lot (part time summer job). The Vaxen were really big expensive machines with 5kW power supplies. Connected to the HSC disk controller with lot sof coax all into a "CI bus Star Connector", which apparantly wasn't that cheap. Upon closer inspection, it was a 2 drawer filing cabinet sized box with no mains power and the coax sockets were hard wired inside.

Those were the days. Real computers and proper operating systems...

[Bob Eager]

Was Dave Atkin still there in the computer service? He and I worked together as postgrads.

The 8800 was a dual 8600, but tha used an LSI-11.

I never found out. Ours was an HSC-50, with one of those slow TU58 tape drives.

Yes, I did the same examination on ours (8800 plus 2 x 8200). I managed that cluster, and did a lot of systems work (and wrote VMS device drivers).

I still have three VAXes....! One of them is set up to switch on and go, and I can log in from anywhere on the house network. Second greediest machine in terms of power (PDP-11 is first).

[Tim S]

Bob Eager coughed up some electrons that declared:

Yes indeed. He was the Systems Manager. Don't know where he is now. Very smart bloke.

we are not worthy...

You must have a big house!

[PeterC]

Chap at work had a big disk with various ICs around the edge and a clock motor and hands. The crash mark was through to the metal and had scratched it.

[Bob Eager]

Chelmsford somewhere. Think I have his email address. We worked on compilers and loaders together many years ago...he at York, me at Kent.

At the time, and still, I teach operating system theory and stuff...

Not too bad. 27 wired network sockets, 9 machines on 24/7. But we use them a lot (four are 'infrastructure'). The VAXes are desktop boxes, yet faster than an 8600....it's even faster if you run VMS on the VAX emulator on the PC!

[Bob Eager]

Oh well, this one is a nice challenge...out of a feed mill in Norfolk!

[Frank Erskine]

On 12 May 2009 09:37:19 GMT, "Bob Eager" had this to say:

What - they have computers in Norfolk now?

:-)

[Andrew Gabriel]

If you want vile environments, try installing a computer next to the track of a London Underground platform. They had to use GEC's mini computers back in the '70's and '80's as they were the only systems they could find back then which didn't crash each time a train pulled out of the station.

London Underground had some of their programmers in an office about 3' above the train roofs at Baker Street station. As the train below pulled out of the station, the images on the terminal screens would roll over sideways. Quite bizzare if you were a visitor and not used to seeing this.

Lots of the GEC machines went into all types of Steel plants too, and many of them didn't have a computer room to put them in.

[Bob Mannix]

Indeed - I visited such a one in the British Steel Stainless Steel smelting plant in Sheffield many years ago. Also used for controlling particle accelerators.

[Andy Champ]

We could mail John Murdie and ask - last time I spoke to him he was still there...

Small world isn't it!

Andy

[dmc]

Not any more - it's in bobs house now

Darren

[Bob Eager]

Once was given an IBM PS/2 server that had come from an agricultural feed merchant - all the PSU vents were choked with some kind of dry food!