test-drb March 2017

test-drb@ccmp.vtda.org

188 participants
235 discussions

Cleaning RK05 packs (Was: LGP-30 Memory Drum Update)

by jnc＠mercury.lcs.mit.edu

> From: Klemens Krause > We clean our RK05 disks in a very robust way: with cheap burning spirit > and paper towels. ... We rubbed away thick black traces from occasional > head crashes and we never removed the oxide coating with this torture. I am about to get a large batch of RK05 packs, so I am interested in the details of this. First, what is 'burning spirit'? (I assume this is a straight translation into English of some German term, but not knowing German... :-) After poking around with Google for a while (hampered no little by the fact that it's the name of a band, and also a term in World of Warcraft :-), it seems like it might be acetone? Noel

7 years, 8 months

Reparando um Vectrex

by alexandre.tabajara＠gmail.com

Oba, post novo no blog! / New post on blog http://tabajara-labs.blogspot.com.br/2017/03/consertando-um-vectrex-com-um-… ---

7 years, 8 months

Intellivision reset switch

by jules.richardson99＠gmail.com

Can anyone who's been inside an Intellivision confirm that there's supposed to be a little foam disc beneath the reset switch plate? I picked a system with a box of cartridges up earlier, half expecting the machine to be dead (I was figuring it was going to be a blob of easily-dead-after-so-many-years custom logic inside, but it's more like a "real computer" in nature). It *was* dead, but the [initial, at least] issue seems to be that the reset switch consists of a metal plate which is supposed to make contact with the PCB when pressed - and presumably is held away from the PCB by something when at rest. Except that there's no "something" in this machine - with the machine the right way up, the plate is free to contact the PCB, holding it in permanent reset. I'm guessing it was a blob of foam, which has deteriorated, but maybe it was a metal spring, or a piece of u-shaped plastic etc. cheers Jules

7 years, 8 months

New HP42s clone almost available

by dave＠661.org

There's a Swiss guy who's made a name for himself by producing working replicas of classic HP calculators. See https://www.swissmicros.com/. I recently discovered his post on Youtube a video showing off an enhanced replica of my favorite HP calculator, the HP42s. This one is called the DM42. Here's the video: https://www.youtube.com/watch?v=0LK7JotR728 -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

7 years, 8 months

OT: PCI Ethernet or USB 2.0 ethernet?

by w2hx＠w2hx.com

Friends, I have an instrument that has an intel motherboard with 400 MHz FSB PCI (not PCI-e). It has a 100 mbps Ethernet card and it would be very useful to get faster networking. The chassis of this instrument is such that I cannot fit a traditional PCI 1GB Ethernet card (I've tried). So I will have to go wifi (which I can make fit because I can remotely locate the wifi antenna). I have 802.11ac both 2.4 and 5 GHz available. While it certainly won't get as good a throughput as a dedicate GB Ethernet card, this is my only option. The question is, whether you think I would be better off using PCI wifi card or a USB-wifi adapter. I should mention the USB on this instrument is USB 2.0, the spec for which claims up to 480 Mbps. Anyone have an opinion which might get me better results? The wifi infrastructure is one constant in this scenario, just looking to see pci- or usb-based wifi card. Since this is wildly off topic, please respond to me directly so as not to bother everyone else :) W2hx at w2hx.com<mailto:W2hx at w2hx.com> Thanks Eugene

7 years, 8 months

Trip to CHM - Hotel/Restaurant Advice

by rickb＠bensene.com

Hello, all, In mid-June, I am planning a trip to Mountain View for two days to visit the Computer History Museum. I plan on flying out of Portland early AM on June 14, checking into hotel, then heading straight to the museum for the day. I will go back to the hotel for the evening, and return to the museum on the 15th, and stay into early afternoon, and then check out of the hotel and head to the airport to return home. I haven't been to CHM before, and am looking forward to spending an extended period of time there. What I'm asking for is help/recommendations in terms of a good hotel to stay at that is relatively close to the museum. I don't want to be in a luxury hotel, nor do I want to be in a dive. I'd also like to be in a place that has a restaurant relatively close by (preferably within walking distance) that I could get some decent meals (breakfast/dinner) while I'm there. Unless this is a topic of general interest to the group, it'd probably be best to reply to me directly rather than post responses to the list. Many thanks, -Rick -- Rick Bensene The Old Calculator Museum http://oldcalculatormuseum.com

7 years, 8 months

WTB: DEC VR241 or HP 6000 670H (or 670XP)

by spectre＠floodgap.com

I'm looking for two items: A VR241 to use with my DEC 380 as a colour head (even better if you have the cable and a spare LK201, since I'm down to my last working keyboard). The VR201 isn't cutting it anymore and I don't think I can use my VR260 with this. An HP 6000 670H hard disk (the big one for the 300 series). XP even better, but I've done just fine with an H. Please include what price you're asking. Thanks! -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com -- Communism doesn't work because people like to own stuff. -- Frank Zappa ----

7 years, 8 months

Cross-talk square-wave?

by jnc＠mercury.lcs.mit.edu

> From: Brent Hilpert > I don't have a full enough picture of the circuit and circumstances to > provide a definitive suggestion but, some principles: > ... > It's not clear C-coupling is what's going on here (the wave shape looks > pretty sharp for what I understand of the circuit/layout). Thanks for taking the time for that detailed message. I suspect, however, that Jon Elson has nailed it (thanks Jon :-); if that's what's happening, it explains why we couldn't understand what the devil was going on! > (You've mentioned both 470K and 270K for the R, could make a difference > to the analysis). Yeah, that was just a typo; going from memory. Noel

7 years, 8 months

Cross-talk square-wave?

by jnc＠mercury.lcs.mit.edu

> From: Allison > FYI this is the same problem designers hit with DRAMS back 40 years ago. This didn't ring (pun not intended) a bell for me; can you say a bit more? > From: Chuck Guzis > I'll offer a suggestion that if your SD card *must* be a significant > distance from its host Like I said, this is a pre-prototype; on the production units, there will be _no_ cable. The SD socket will be about 1-2" from the FPGA. > From: Dwight Kelvey > this behavior on my PDP-8/e where a 7474 flip flop chip was bad. The > input looked great and the output was "half baked" There's no chip at all on the driving end of the line (just that 470K resistor); we see this with the SD card _unplugged_. And we see the exact same thing on several lines. I'm still not clear, from the discussion, how exactly that nice 'square-wave' interference is happening - could it be capacitative crosstalk? (I'd have thought capacitative cross-talk would be inverted - driving a positive voltage on one 'side' of the 'capacitor' would, I would think, induce an oppposing voltage on the other. But I'm clearly no EE! :-) Noel

7 years, 8 months

Anyone want a Sun T-shirt?

by cclist＠sydex.com

It's what, 27 years old... Trying to de-junk my clothes closet, I ran across an XL t-shirt bearing, on the front, a image of a ladybug with a red circle and bar across is and the legend "Getting out the last bugs". On the back, it has the Sun logo and "SunStruck 4.1.89 (Wanda)". It's in decent condition and probably dates from the time my wife worked at Sun, even though she had nothing to do with the project in question. Anyone want it? Pay for first-class mail (I'll stuff it into an envelope) and it's yours. Otherwise, it goes to Goodwill. --Chuck

7 years, 8 months

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test-drb March 2017