Re: PDP-8 core memory problems.

2016-09-07 17:33 GMT+02:00 Doug Ingraham : > The most likely cause of what you are seeing is a broken wire when the > plane was originally assembled. The wire was pulled back a few cores and > the end stripped. New wire was soldered to old, insulated and then they >

Re: PDP-8 core memory problems.

The most likely cause of what you are seeing is a broken wire when the plane was originally assembled. The wire was pulled back a few cores and the end stripped. New wire was soldered to old, insulated and then they continued threading in that wire. Over the years the solder joint has degraded

Re: PDP-8 core memory problems.

So what are the other options? * Trying to repair the unit. Every plane is soldered together with the ones nearby to convey the X/Y signals. This can probably be undone with a patience and soldering braid. But what are the chance that the X/Y wires gets lose then? Are those soldered or welded

Re: PDP-8 core memory problems.

From: "Mattis Lind: Tuesday, September 06, 2016 2:11 AM * Use a PDP-15 MM15 stack and sense/inhibit boards. I have several off these. Adding a small backplane, put the X/Y drivers, sense amp/inhibit drivers and level converters there and then adapt to the existing slots for the memory module.

Re: PDP-8 core memory problems.

> > I'd tend to be more pessimistic about this working. > > There are different requirements in winding a wire for purposes of inhibit > and sense. > In the 3-wire arrangement the winding of the combined wire has to meet both > sets of requirements. > > Specifically, for this case, in a 4-wire

Re: PDP-8 core memory problems.

On 09/05/2016 09:28 PM, Brent Hilpert wrote: I'd tend to be more pessimistic about this working. In the 3-wire example there you can see how the S/I wire was split in half with a special resistor network at one end to allow inhibit current flow while at the same time configuring it as a

Re: PDP-8 core memory problems.

On 2016-Sep-05, at 4:36 PM, Jon Elson wrote: > On 09/05/2016 05:46 PM, Mattis Lind wrote: >> måndag 5 september 2016 skrev Jon Elson : >> >>> On 09/05/2016 01:59 PM, Mattis Lind wrote: >>> I have now concluded that the fault is in the core memory module itself.

Re: PDP-8 core memory problems.

On 09/05/2016 05:46 PM, Mattis Lind wrote: måndag 5 september 2016 skrev Jon Elson : On 09/05/2016 01:59 PM, Mattis Lind wrote: I have now concluded that the fault is in the core memory module itself. The sense winding is broken on bit plane 7. Have you actually

Re: PDP-8 core memory problems.

måndag 5 september 2016 skrev Jon Elson : > On 09/05/2016 01:59 PM, Mattis Lind wrote: > >> >> I have now concluded that the fault is in the core memory module itself. >> The sense winding is broken on bit plane 7. >> >> >> Have you actually ohmed out the sense/inhibit

Re: PDP-8 core memory problems.

måndag 5 september 2016 skrev Jon Elson : > On 09/05/2016 01:59 PM, Mattis Lind wrote: > >> >> I have now concluded that the fault is in the core memory module itself. >> The sense winding is broken on bit plane 7. >> >> >> Have you actually ohmed out the sense/inhibit

PDP-8 core memory problems.

For some time I have slowly been working on restoring our PDP-8 to operating condition. Here are some notes on the progress: http://www.datormuseum.se/computers/digital-equipment-corporation/pdp-8 It is sort of working now after reforming capacitors in the PSU, adjusting memory currents and