A successful VCF, restoration project updates, IRIS is not well and keeping cool
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Rather later than anticipated due to holiday and 'real' work activities by many at the museum, here is an update on what has been happening since the VCF.
Well, I think we can safely say this was a resounding success with lots of positive feed back from the twitterati, blogsphere and the many published news articles on the net. As with many events, we were not able to accommodate everyone and we have been very encouraged by the number of individuals, groups and companies who have made enquires about wanting to be involved in future events. The one question that everyone is asking is when the next VCF-GB event will be... well, that is something we are still discussing internally but as yet we have not made any decisions on when the next event will be.
IRIS Air Traffic Control
We were hoping to show of the Air Traffic Control system during the VCF but, unfortunately, having run reliably for many months it has developed several faults just prior to and also since the VCF event. The first sign of a problem was the radar replay unit suddenly shutting down with a hardware fault and this has happened quite a few times since. This was soon followed by the Newman solid state disk system failing to respond to commands when initially switched on and the final fault was in one of the large green radar screens that has developed a power supply fault. The result is IRIS is currently out of action for the foreseeable future until the problems can be fixed.
The radar replay unit is an important part of the system and is used to supply the radar data to be processed by the PDP 11s and shown on the green radar screens, but it is the one item we have no spares or documentation for. The DAT tapes holding the radar data are also in a proprietary format (and most likely compressed) so are unreadable by any other system. Due to the possibility that the radar replay unit becomes unusable we need to find an alternative method of supplying the radar data to the rest of the system ie a PC. As the data cannot be recovered from the tapes, it means we need to capture the data as it is sent out by the replay unit. This uses a synchronous serial interface but we currently don't have any systems that can interface to it (ie one with a synchronous serial card). Commercially available PCI cards do exist but are very expensive and beyond our budget at the moment, so we are still trying to source a suitable card.
If anyone reading this has a PCI (or other interface type) synchronous serial card that they are willing to donate please get in touch - we actually need two serial ports so that means two cards. The alternative is to develop our own interface card which is being looked at. Once that is solved we then need to write some software to capture the data and enable it to be played back, but as with all things the data format and protocol are not trivial and we have very little documentation on it.
Progress is being made with the 2966 restoration, with the current effort being on getting some of the removable EDS80 drives working reliably (thanks to replacement main and motor bearings) so a diagnostic pack can be used to test the main cabinets. So far things are looking good with at least one drive working well. The pack has been run-up and proved to work but because of the age of the drives and the fact that we only have one diagnostic pack, it is too risky to use it for general diagnostic work.
The next stage is to design and build a disk interface board to enable the data from the diagnostic pack to be captured onto a PC and software written on the PC to simulate the disk interface. We can then use the PC as an EDS80 and run the diagnostics without fear of a drive or pack failure (which has actually happened in the last few weeks when an old scratch pack was loaded and caused a head crash due to one of the platters being out of alignment). Progress on this restoration can be found on the projects page.
Harwell Dekatron Computer
Tony F and team are making very good progress in restoring the system to a working state. In the past few weeks, Tony has been able to demonstrate various parts of the relay control system to the point where it can actually execute basic instructions that allows it to read blocks of instructions from several of the tape drives. This is a good sign indicating a lot of the control logic is working. He has managed to put together a sequence where it reads a block from tape 1 which instructs the system to read a block from tape 2 which instructs the system to read a block from tape 3 which then reads from tape 1 again. This can then repeat several times over a period of 10 minutes. It's a very impressive demonstration of the system, but also shows just how slow the system really was.
Progress is also being made on the Dekatron store exerciser but there are still a few teething problems to resolve before it can be used on the system itself. Tony can usually give a demonstration of this on Saturdays if he is in and enough people ask. You can follow the progress of the HDC restoration on the projects page.
Keeping things cool
Unfortunately, unlike us, many of the large systems can't just wander down to the museum shop and buy an ice cream or ice lolly to cool off.... Summer is again upon us and the difficult task of trying to keep the working exhibits cool is an on-going challenge. Many of the larger systems (and even some smaller ones) were originally designed to work in temperature-controlled computer rooms or large cool offices with banks of air-conditioners removing the heat. But no amount of high-powered air blowers and fans in the systems can keep things cool when the room temperature gets to nearly 30C. In fact, one Saturday it go so hot we had to switch the machines off for fear of them overheating.
Several of the systems have now been fitted with temperature indicators so we can keep an eye on them, and the ICL 2966 (which can generate many Kilo Watts of heat) has an air ventilation system that vents the hot air out of the building.
It would be nice to have a cooling system in the museum but it is just not practical in a building so big and so old, with many holes and gaps in the window frames (and the roof in places!). We try to do our best to ensure our systems are running when people visit but please be aware that it may be necessary to shut off systems at times to protect them from heat damage. At least it can give the operators time to wander down to the shop to get something cool.