SCSI options for PDP 11/23

On Wed, 27 Feb 2002, Zane H. Healy wrote: It did have the M8186 11/23 CPU in the 11/03 chassis when I got it, not that that means anything. I did change the memory module to a 128KW MSV11-LK. There's an older Q-bus VAX system at the University that will probably be taken out of service soon, and there's a chance I can grab its SCSI controller (I'm not sure exactly what it has, but I know it has one). Its mostly a hobbyist system, in that I paid for it personally, and if it weren't for it being a hobby, I would have given up a long time ago. :) Its kind of hard to explain, but I'll try. I work for a university on a National Science Foundation funded project that provides satellite communication to scientists at the geographic south pole, and a few other assorted places in the Antarctic. Normal commericial satellite communication isn't affordable to the scientific community, so the operation uses old satellites (ranging in launch year from 1967 to 1977) that are no longer usable for their original purpose, such as imager failures in the case of the older GOES satellites. We also use ATS-3, the oldest continously operating satellite in the world. It took the first color pictures of the earth from space in 1967. Also, being low on station keeping fuel, which causes the orbit to drift north and south of the equator, so that it its no longer geostationary is another reason. That's good for us, because at geostationary orbit, you can only see down to about 80 degrees south. With the drift, you can see the poles for about 6 hours a day. In order to perform maneuvers (fire the jets) on a spin-stabilized satellite, you have to synchronize your commanding with a reference point (usually the sun). If you were in the 1970s and wanted to design a reliable "portable" computing system for each launch site required around the world, what would you use? You guessed it, a PDP-11. The software was on an RX02 along with RT-11. Anyway, we built our own command equipment awhile ago with a small microcontroller. This was intended for commanding where the timing isn't critical, such as turning things on and off, switching sensors, etc. The attitude of a spinning satellite precesses slowly over time, and you correct it by firing jets in a synchronized manner, which we can't do with our equipment. The attitude starting to be off enough to where it needs to be corrected. Lacking the funding to develop something new, combined with everyone assuming I wouldn't be able to revive this system, I decided to rebuilt it on my own. (We only had a few pieces of the original system that attached to the DMA and PIO interfaces, which didn't work, and none of the PDP equipment). It was working pretty well until the RX02 incident. I was hoping I could scrape up a SCSI controller from somewhere around the university, so I could have a longer-term storage option. So in the next couple of months, it will get used for a "production" purpose, but then it won't be needed for quite awhile.