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Yet another PDP-8/m - this one is with the programmers console: https://www.ebay.com/itm/116163448173 There is glut of these now. :)

Where in the world are you?

If you have worked near a motor-generator set for a mainframe like a CDC CYBER then you wouldn't complain about a little hum from these "power conditioner" toys. To make things worse on mainframes like the CDC CYBER there was the constant 400 Hz 3 phase supply noise. I didn't bother me too much...

I wonder how these machines booted without an M847? Could the M848 be used to restart as long as core is not corrupted? So maybe you could have just one M847 and boot all 4 machines with it and then just keep the M847 in a safe place. No console board seems very strange though. Yes we all have...

Good question, but I wouldn't complain as the M837 gives you the option of adding more core (or Roland's SRAM based memory board). Of course at the current price it is "unobtainium" for many (most?) of us. Hopefully the current "glut" will bring the prices down to more reasonable levels. One can...

There is a sudden "oversupply" of PDP-8/M machines: https://www.ebay.com/itm/235452128279 (1 available) https://www.ebay.com/itm/226095594926 (4 available) The prices are silly, but it is Ebay so no surprise.

Paul, I made the base and the case 2 mm thicker which means you need screws which are 2 mm longer than what Chris designed for (8 mm versus 6 mm). The same applies to the DB9 UART connector. The screws need to be 2 mm longer than the originals. I had all these in "stock" in supposedly all metric...

Hmmm - during the "frozen" state a single console key press unfreezes the system and the count continues without ever freezing again. The key-press shouldn't be serviced by the monitor program in EPROM, but somehow the pending key-press affects subsequent behaviour. Any thoughts?

I finally received my hacked case, base plate and reset button 3D printed in PLA. The result is quite pleasing and much more sturdy than the first Nylon version I got from JLCPCB. There is no more flexing when you toggle in programs via the front panel switches. The assembled unit is much...

It turns out that if I enter and start the 4 word program above using the following console commands, the "freeze" does not happen: d 0 7001,2101,5001,5000 st 0 The FP6120 AC display nicely counts from 0000 to 7777, wraps around to 0000 and continues counting up to 7777 forever. Doing the...

I have been using the SBC6120-RBC for a few years, but recently Chris Tersteeg has created a nice FP6120 front panel clone of Bob Armstrong's original. I have now noticed that there may be a problem with the SBC6120-RBC because the following little count program does not behave as expected on...

How long did it take to build the kit?

Very nice. I have all of Oscar's previous creations, but this looks the best so far. I am on Oscar's list for the next shipment - or at least I hope I am. :)

Just in case someone else might want to play with this, I have uploaded the sturdier version of Hideehoo's case design file and the STL files for case top, base plate and reset button to my Google Drive: Tom's hack of the SBC6120 case

I sliced the modified case parts (bottom plate and top case) in PrusaSlicer and overnight attempted a PLA print of the bottom plate with my Creality Ender 5. Today morning it was almost "finished", but it printed about 50% in the air without extruding any filament. I assume somehow the nozzle...

I have tried the latest version of Cura, but it no longer runs under Windows 7. Prusa Slicer works fine.

I managed to increase the thickness of the top case and the bottom plate, but Ultimaker Cura is unable slice the STL file: The build volume should be fine for the Creality Ender 5 I am trying to slice for. I have also tried with the Chris's original top case and bottom plate STL files, but...

I have downloaded and installed DesignSpark Mechanical Explorer. The case design file "SBC6120-RBC Front Panel Case.rsdocx" opens nicely and I can view the various components. Making changes is not obvious for someone who has never played with mechanical CAD programs before. There are some...

I actually like the white front panel. :) The only thing I am not 100% happy about are the 3D printed parts I got made in black Nylon. As Hideehoo wrote it may well be that the problems are specific to the material and may not exist with PLA. I think the following improvements could be made...

I think you have to be creative even with Windows 10 to prevent it from trying to upgrade you to an unusable machine. I am slowly switching all my PCs away from Windows 7 and 10 to Linux and will only keep one Windows 7 machine for legacy tools like EPROM/GAL programmers etc.