pbirkel@gmail.com
Veteran Member
One platter that was held in place by springs; non-removeable, so track alignment was stable.So was the RK05-F two platters, or just one double density RK05 that didn't have to worry about pack removal?
One platter that was held in place by springs; non-removeable, so track alignment was stable.So was the RK05-F two platters, or just one double density RK05 that didn't have to worry about pack removal?
How much memory is in these CNC 8M's? The G104-G227 modules would indicate 4K, so why would they have a KM8-E (M837) installed? What 'value-add' does a M837 bring to a 4K 8/E?There is a sudden "oversupply" of PDP-8/M machines:
https://www.ebay.com/itm/226095594926 (4 available)
The vendor selling just the one machine didn't include any details. The one with the 4 machines I emailed and got to add more photos. The comments below are about the machine shown from them.How much memory is in these CNC 8M's? The G104-G227 modules would indicate 4K, so why would they have a KM8-E (M837) installed? What 'value-add' does a M837 bring to a 4K 8/E?
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Also missing is a console interface and some sort of access to any other peripheral. And without a front panel there must have been an M847 boot card which is not there. T
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If everything shown works correctly they should go for around $1000 each. About the same as if they are parted out. In my collection I have everything but the RTC card, the VC8E option boards and an 8/m case.
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I hope none of them sell for that asking price although if they do then I have an unexpected source of retirement income.
CNC controllers were almost always more complicated than what amounted to a "spooler" for a set of pre-packaged signals to the CNC device servos. More commonly the controller accepted a compact description of the tool path (see: RS-273, RS-274, and Gcode) and was used to interpolate between control points in order to step the servos at a feed rate suitable to the tool and material. That included curves with given radii and so on. Cutting speeds could be interactively determined by the operator on a case-by-case basis, as well as the cutting head aligned WRT the stock and repositioned as necessary. An operator control panel was serviced by the (CPU) controller. Simple paths could be manually set up by the operator, perhaps then saved for reuse, in addition to feeding in a stock-part tool path description from a paper-tape library.I am guessing they removed the card(s) attached to cables that were attached to the CNC machine. The CNC machine may still be in service using a more modern control computer. A custom program in an 8 wouldn't need more than 4k to hand commands off to a CNC mill at timed intervals.
Yet another PDP-8/m - this one is with the programmers console: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.
Yet another PDP-8/m - this one is with the programmers console:
Yet another PDP-8/m - this one is with the programmers console:
Vintage DEC PDP-8/m Minicomputer, Complete and Working | eBay
The LED for data bit 11 is also quite dim (these are very early Monsanto LEDs, and many have already been replaced.). - M849 RFI Shield (also works as tinfoil hat).www.ebay.com
There is glut of these now.
Most cases you could probably leave this out and be fine. But I suspect if you put the A/D boards right next to the core you would experience measurement difficulties. I suppose I should be blunt. Your measurements would be noisy. More blunt? Your measurements would suck. But that is probably not the original reason for it. There was probably some early CPU board that when placed right next to the core would glitch occasionally. There were probably two solutions, the M849 and fixing the glitchy board and both got used from that point forward."M849 RFI Shield (also works as tinfoil hat)."
Most cases you could probably leave this out and be fine.
Thanks Al! I was not thinking about it from the standpoint of the noise getting into the core memory sense amps. That makes sense. (I really shouldn't have.)You need it to isolate the sense amps from adjacent board digital logic noise, which you can deal with by rearranging the cards.
Yes, the scale of the attempted fraud is scary. It appears that Ebay has some API which allowed this fraudster to upload a huge amount of listings in a very short amount of time. The fraudster clearly has a very high level of expertise. I wouldn't be too surprised if this comes from a "not so friendly country" and is more than just a single clever fraudster.Wow, haven't seen fraud at this scale in awhile. Thanks for the warning in general!