A very sad PDP-8/S

On Sat, Nov 3, 2018 at 1:12 AM Lyle Bickley via cctalk <cctalk at classiccmp.org> wrote: Yes. Start by looking at http://www.ricomputermuseum.org/Home/equipment/pdp-8s At a quick glance, I see you _might_ have 2-3 cards in wrong slots near some intentional gaps. Check that. The open slots at the back are for the I/O cables. The open slots near the memory stack are supposed to be empty with the one possible exception where I see in your photo you have a single-height amber card and the RICM PDP-8/S appears to have a dual-height amber card. I don't have the printset up so I can't tell exactly what's going on there. Could be normal variation as they made changes across the run. Yes. You just need enough amps at +10V and -15V to fire it up. What I don't know off the top of my head is the difference between a table-top and rack-mounted system. RICM has pictures of a rack-mounted system. Mine is table-top. It's entirely possible that yours was pulled from a rack and the PSU stayed behind. Yours might never have had covers like the desktop unit. Yes. "for the version you have" is important. I don't think there's exactly one way they built it across multiple years. There can easily be a module or two different between different manufacturing dates if there was a large ECO. Unlike every other machine I've worked on, the -8/S has *two* front panel boards. One is very short and has just the switches and sits in slot 1. The other is full-sized and has only the lamps, no switches and sits in slot 2. I see from your photos, that board is missing. Given that it's fairly simple, you might be able to find a Unibus hex-height protoboard and fabricate a replacement. The lamps might be interesting to source - ISTR they have 28V filaments, underdriven to give them a long lifetime. I can't recommend the original lamps anyway - they are not the bi-pin bulbs used in later models (PDP-8/L and newer). They have these brittle leads coming out of the glass and no plastic base. I have several in mine that had the leads break off right at the glass. Even if the filaments are intact, these bulbs are essentially dead. I do not presently have any replacement bulbs of any type for mine. Yep. All the I/O was external on the Negibus, even the console TTY (there's a PT08 in the base of an ASR-33 that was standard for this model). I didn't get the TTY with mine (it was long gone, to a Ham club, I was told) so I don't have a console SLU either. Once I get the CPU working, I'll have to fabricate a PT08 replacement. There just wasn't room in the box for any I/O. The backplane on this model is close to half the size of the backplane on a Straight-8. Definitely. -ethan