Re: XKCD on what we're doing
On Mon, Dec 18, 2017 at 1:25 PM, Paul Koning via cctalk < cctalk@classiccmp.org> wrote: > https://xkcd.com/1909/ > > Our community isn't just about that, but it's part of what makes us tick. > Preserving knowledge is an ongoing problem and getting harder to solve. Vint Cerf talks about it a lot. https://www.youtube.com/watch?v=GV0A82TCrf0 https://www.nitrd.gov/news/digital-vellum-and-archives.aspx
Re: IBM MT/ST recovery; was: IBM 3480 DEC TKZ60 inquiry
http://www.computerhistory.org/collections/catalog/102662523 Digi-Data made a widget to read the tapes as well. On 12/18/17 12:57 PM, Chuck Guzis via cctalk wrote: > Forgive the top-posting on my own post, but I think it's appropriate: > > Evidently, the client used an MT/ST to emulate a 2741 and the > organization had a S/360 with a 2495 Magnetc Cartridge Reader: >
Re: eBay: MEMOREX 3693-2 & 3690-2 Disc Drive Mainframe IBM 3370-2 VINTAGE
Excellent! Congrats Guy. Looks like modempot really needs to move out of his building in a hurry. I think between me, you, Carl, Bob, the museum and a few ebay buyers we got all of the big stuff saved. Marc On Dec 17, 2017, at 4:44 PM, Guy Sotomayor Jr via cctalk wrote: To let folks now, I’ve acquired the drives and am currently making arrangement for one of the local collectors to pick them up if I’m unable to and store them until I’m able to get them to my place. So they’ve been saved and I’m looking forward to being able to attach them to my 4331. TTFN - Guy >> On Dec 16, 2017, at 1:48 PM, Noel Chiappa via cctalk >> wrote: >> >> From: Guy Sotomayor Jr > >> I *really* want them and I'm within an hour (usually) of where they >> are. The problem is that right now I'm on a business trip until the end >> of the month and he needs this gone prior to 12/31. > > Why don't you reach out to the person and tell them you _really_ want them, > maybe they'll be able to let it go until you get back? > > Or is there someone in the Sacramanto area who can pick them up and hold them > until Guy can get them? I would offer to, but I'm on the wrong coast :-( > >Noel
Re: IBM MT/ST recovery; was: IBM 3480 DEC TKZ60 inquiry
Forgive the top-posting on my own post, but I think it's appropriate: Evidently, the client used an MT/ST to emulate a 2741 and the organization had a S/360 with a 2495 Magnetc Cartridge Reader: http://ed-thelen.org/comp-hist/IBM-ProdAnn/2495-5.pdf I have to confess that I've never seen one of these "in the flesh". I doubt that any exist today, but I'll be happily disabused of this notion. --Chuck On 12/18/2017 09:14 AM, Chuck Guzis via cctalk wrote: > Well, this is part of the job. I got the potential client to send a > photo of the cartridge--and he managed to get a 3480 cartridge for > comparison. > > It's clearly an IBM MT/ST cart: > > https://imgur.com/a/K9vyg > > Anyone around who can recover the data from these things? > > --Chuck
XKCD on what we're doing
https://xkcd.com/1909/ Our community isn't just about that, but it's part of what makes us tick. paul
Re: IBM MT/ST recovery; was: IBM 3480 DEC TKZ60 inquiry
On 12/17/2017 09:52 PM, Jon Elson wrote: > There were several DIFFERENT formats used with these standard tape > cartridges. I have some old CDC Patriot tape drives that did a > serpentine single track at a time format on a 3480-compatible tape. I > don't think any DEC drive supported the 18-tracks-wide IBM 3480 format. > I think DEC's drives were also serpentine. If they are really from an > IBM compatible system (really too late for 360, most likely 370 systems) > then I think only an IBM-compatible drive would read them. Wikipedia > says the 3480 was introduced in 1984. Well, this is part of the job. I got the potential client to send a photo of the cartridge--and he managed to get a 3480 cartridge for comparison. It's clearly an IBM MT/ST cart: https://imgur.com/a/K9vyg Anyone around who can recover the data from these things? --Chuck
Re: Odd Connections to Rectifier?
On Mon, Dec 18, 2017 at 8:06 AM, Rob Jarratt via cctalk wrote: > I am reverse engineering the schematic for the input stage of my H7862 PSU. > I have come across a KBU6J bridge rectifier which seems to be connected only > to the two middle pins, which are the AC inputs. I can't see any other > connections. Before I desolder it to verify there are no connections I can't > see, does this make any sense? I don't think it makes sense. With no connections to the other pins (+ve and -ve DC out I assume) then there is no DC (or AC) path through the rectifier, whatever the input, at least one diode is reverse-biased. Unless you are depending on the diodes to break down in a controlled way (and I can't believe it depends on that) then the bridge will do nothing. -tony
Re: Odd Connections to Rectifier?
> > I am reverse engineering the schematic for the input stage of my H7862 PSU. > I have come across a KBU6J bridge rectifier which seems to be connected only > to the two middle pins, which are the AC inputs. I can't see any other > connections. Before I desolder it to verify there are no connections I can't > see, does this make any sense? > If it is the main rectifier, continuity checks should show a dead short from the other two pins to the main smoothing capacitor(s) or maybe a very low resistance through a surge limiting resistor or inductor either of which should be easy to spot once you know what to look for. If it is not the main rectifier, could the AC inputs be connected across a current sensing resistor in the mains input with the DC outputs going to an optoisolator or something like that? Seems a bit unlikely though as the voltage drop across the rectifier would likely be too large compared to the voltage available across any current sensing resistor. Regards, Peter Coghlan.
Re: Odd Connections to Rectifier?
On 2017-Dec-18, at 12:06 AM, Rob Jarratt via cctalk wrote: > I am reverse engineering the schematic for the input stage of my H7862 PSU. > I have come across a KBU6J bridge rectifier which seems to be connected only > to the two middle pins, which are the AC inputs. I can't see any other > connections. Before I desolder it to verify there are no connections I can't > see, does this make any sense? It's barely conceivable it could be getting used as a clamp or snubber. If you haven't found another bridge or rectifiers for the mains rectification, then keep looking for unseen connections to this bridge.
Odd Connections to Rectifier?
I am reverse engineering the schematic for the input stage of my H7862 PSU. I have come across a KBU6J bridge rectifier which seems to be connected only to the two middle pins, which are the AC inputs. I can't see any other connections. Before I desolder it to verify there are no connections I can't see, does this make any sense? Thanks Rob
