Interest in a PDP-8/e/a/f/m 32K RAM kit?

On Mar 4, 2014 8:25 PM, "Vincent Slyngstad" <vrs at msn.com> wrote: heavily prototype works, and that's a big deal. Maybe it doesn't work if you move your DMA device to the other end of a 20 foot ribbon cable -- I doubt that's been tested. On the other hand, you shouldn't need to put it there, as this thing potentially frees up a lot of slots. I should say that only the memory pins, not the whole Omnibus, are playing fast and loose here, and the only devices connected to those should be CPU, memory, and maybe a DMA device. (Does anyone actually put more than one data break device on their Omnibus?) My point isn't that there's anything wrong with making a board that doesn't completely meet DEC specs, as long as that's understood. The problem is trying to represent something as meeting DEC specs when it probably doesn't, and using an incorrect analysis to try to support the claim that it meets DEC specs. Yes, it will most likely work in small or even medium-scale Omnibus systems. No, it might not work reliably in a large system, such as I previously described, which did have multiple data break devices. The length of the bus is also a factor, even if you have few or no data break devices. The system in question had one 40- and two 20-slot boxes, with fairly long cables. To some extent the long cables may actually be better than short ones. If DEC didn't spec the maximum slew rate, that was probably because at the time there weren't any cost-effective interface chips that had fast enough slew rate to be a problem. There certainly are now, and the lack of a spec doesn't mean that it's OK to use arbitrarily high slew rate drivers. All that said, I'm happy to see the design published, and boards and/or kits made available. I know what a large amount of work that can be. I'd be happy to buy two of them, knowing that they most likely don't actually meet DEC specs. Eric