Ken, Core places being hand wired amazed me as well. The maintenance panels on the Honeywell mainframes were hand wired as well. They were works of art with lots of toggle switches and lights (the later models switched to LEDs). I could see most of the internal registers using a fancy scroll wheel to select what register the lights should show. I could also enter small diagnostic programs and single step through them using the panel.
Most of our core memories were 256K of 36 bit words (with a few spares for each location). They took up lots of floor space. I suspect the fact that the power supplies had to drive that much equipment was what made them sing. - Rod > On Apr 25, 2023, at 9:25 AM, KenUnix via cctalk <cctalk@classiccmp.org> wrote: > > Rod, > > Never heard the singing. Switch room's were too noisy. > > It always amazed me that those core planes were hand wired. I guess by > little people. Or, big people with little hands. > > On the PDP 8/I they were 4K plug in affairs. > > Ken > > > On Tue, Apr 25, 2023, 9:14 AM Rod Bartlett via cctalk <cctalk@classiccmp.org> > wrote: > >> Ken, >> >> This discussion does my geezer's heart good. >> >> I used to maintain Honeywell mainframes in the late 1970s, some of which >> had core memories. Tapping them on the floor wasn't an option since they >> were such huge beasties but they did have space for spare bits. I've >> swapped to the spare bits or replaced sense amps to fix many a core >> problem. Something I'll never forget is the way the power supplies "sang" >> when running memory diagnostics on the core units. I could always tell the >> diagnostic was done when the singing stopped. >> >> - Rod >> >>> On Apr 24, 2023, at 2:11 PM, KenUnix via cctalk <cctalk@classiccmp.org> >> wrote: >>> >>> David, >>> >>> I could tell you I had an experience where I had a stuck bit in core >> memory. >>> >>> It was in a trunk frame in a #2ESS AIS. >>> >>> I removed the core package and tapped it on the floor, reinserted it and >>> the trouble cleared. >>> >>> Sticky bit! Ha >>> >>> I only knew that because it happened to me on my old PDP-8/I.. >>> >>> Ken >>> >>> >>> On Mon, Apr 24, 2023 at 1:50 PM David Gesswein via cctalk < >>> cctalk@classiccmp.org> wrote: >>> >>>> On Mon, Apr 24, 2023 at 11:11:35AM +0100, Pete Turnbull wrote: >>>>> On 23/04/2023 22:52, KenUnix via cctalk wrote: >>>>>> Pete, >>>>>> >>>>>> Did the 8E have core or solid state memory? >>>>> >>>>> It had both, but I didn't put the core boards in the dishwasher. I >>>> figured >>>>> they might be too delicate for that, so I rinsed them by hand in the >>>> kitchen >>>>> sink. >>>>> >>>>> I should have said that in my original post. >>>>> >>>> >>>> I assume your referring to the core electronics boards and didn't wash >> the >>>> core plane. >>>> >>>> I've never used the dishwasher. I've hand washed R, W, G and M type >> boards >>>> in >>>> sink with dish soap and soft bristle brush, rinsed, then blew off with >>>> air compressor, then finish dry with fan. For pots and other >>>> components that I wasn't sure how well they were sealed I used damp >> brush >>>> or >>>> cloth around them. Rest got dunked. No obvious issues from washing. >>>> >>> >>> >>> -- >>> End of line >>> JOB TERMINATED Okey Dokey >> >>
