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101090 discussions

DEC H-500 Computer Lab pins and docs (was Re: Straight 8 up on Ebay just ...

by COURYHOUSE＠aol.com

I wonder if any of the other digi labs leads are comparable? We have fabratek and a few other brands. We got a bit obsessed with trainer type gear for electronics and physics 'this what that got young people interested back when' display. if there are any list member with a small turret lathe that would be nice to make pins with. pretty labor intensive. Better would be small Brown and Sharpe screw machine would make buckets of them once you got the machine all set up to make the run. Or cnc machine ( I never ran one of those) --- or as mentioned casting some. I will look and see is we need any pins. Ed#. In a message dated 7/19/2016 11:30:10 P.M. US Mountain Standard Time, v.slyngstad at frontier.com writes: From: Karl-Wilhelm Wacker: Tuesday, July 19, 2016 5:21 PM > This company does custom tapered pins in brass - > There are others out there I'm sure. > > I would find out what their minimum is and get a bulk order together. > > http://www.stanlok.com/Taper_Pin_Pages/an386.html > > A place I worked for in the past had www.mill-max.com do a custon part for > them, > in the 100's - I would talk to them about a part also. >From what I can gather from the websites you referred me to, the tapered part of the pin's dimensions are very close to the woner if fabratecnarrow end of a standard taper #4/0 in the 3/4" length? Have I done the math right on that? >From there it would seem to be a matter of getting a way to mount the wire, and optionally to shorten the overall length of the pin and wire attachment to .65" from .75". (Or maybe just slot the pin's fat end, solder in the wire, and call it good.) I also thought about using a taper reamer to create molds and perhaps casting with solder around the fluxed wire. (Casting brass or bronze seemed to require more heat than I could generate easily.) (For some reason that I've forgotten over the years, my eBay search for suitable pins looks for "42107" and "42279". Never gotten any results for it, though.) Vince

9 years, 6 months

DEC H-500 Computer Lab pins and docs (was Re: Straight 8 up on Ebay just now)

by ethan.dicks＠gmail.com

On Tue, Jul 19, 2016 at 5:01 AM, <COURYHOUSE at aol.com> wrote: > also a Rare Digital DEC H-500 Computer Lab, 1960s, Same Switches as > PDP-8/I, Vintage for 700+ > > ( we have an extra one of these Computer Lab, if anyone here is > interested) Does anyone have a modern source of pins that fit the socket holes in the Computer Lab? ISTR there are a few of us here who have an H-500, but very few, or no, patch cables. I think Molex pins have been tried and rejected. Also, the 1969 Computer Lab Handbook is on bitsavers (in 'dec/handbooks'). I recall a 8.5"x11" book on the Computer Lab, newer layout, probably a 1970s publication date, possibly a teacher's guide. I was given one as a kid, but it vanished decades ago. Anyone remember this? Anyone have one for scanning? -ethan

9 years, 6 months

Another pdp-8 auction at 25k

by barythrin＠gmail.com

http://m.ebay.com/itm/DEC-PDP8-I-MINICOMPUTER-PDP8-PDP-8-PDP-8-/201627112300 Did someone already post this other pdp-8 auction? Same semi-ridiculous starting price as other straight 8 but i honestly don't know enough about PDP to know what this is or if its not a straight version. ?Seems like a museum piece though although perhaps all of you PDP collectors have a similar setup :-)?

9 years, 6 months

LASERS! && Freemont Street LED array (was Re: Cray J932SE (was Re: Straight 8 up on Ebay just now))

by jnc＠mercury.lcs.mit.edu

> From: Mouse > my impression is that they're only for pre-prepared displays, and only > some displays (notably those that don't involve the beam turning any > sharp corners My vague recollection is that they could do pretty sharp corners, but it's been decades. IIRC, they were multi-coloured. > Turning sharp corners is the hard part with mechanical deflectors like > mirrors, as it means very high acceleration of the mechanical parts. Probably the trick is to do what old voice-coil actuator drives did for multi-track seeks, which was to evenly accelerate up to maximum velocity, coast at that until you got close to the target track, and then evenly ramp down, so that the head assembly's radial velocity goes to 0 as you get to the target track. (If you're not moving enough tracks to do the whole thing, you only ramp up part-way, then ramp back down.) The RK05 drive did this with fancy analog circuits, but these days one would do it in software. I would assume one would do something similar with the mirror; evenly accelerate up to maximum slew rate, then back down at the end of the move, so that when one gets to the corner, the mirror is mostly stationary, and so not so much force is needed to sharply change directions. Of course, this might make the parts of the line where the mirror is moving slower brighter, but perhaps one could tweak the brightness to compensate. Noel

9 years, 6 months

Seagate 50-pin SCSI drives

by sales＠elecplus.com

A reseller in GA is dumping some online inventory that they used to sell on ebay. Included are 23 SEAGATE ST32500N HARD DRIVE If interested, email to Mike Roetzer [mike at tbfcomputing.com] Not affiliated with the seller at all. Cindy Croxton

9 years, 6 months

Straight 8 up on Ebay just now

by COURYHOUSE＠aol.com

I just put in pdp-8 in ebay search and saw it last nite -Ed# In a message dated 7/19/2016 12:24:15 P.M. US Mountain Standard Time, pontus at Update.UU.SE writes: I can't find it, does anyone have a URL? /P On Mon, Jul 18, 2016 at 01:58:12PM -0700, jim stephens wrote: > 25,000, Alexandria, Va. > > Josh Dersch can have one for his home and for work. > > BTW, about the other nice system noted here, I was hoping the 11/20 would > stay off the radar and not go for a zillion bucks, so much for that idea. > At least I have the means to go to Tucson and get it if I'm nuts and go for > it. > > Thanks > Jim

9 years, 6 months

Straight 8 up on Ebay just now

by jwsmail＠jwsss.com

25,000, Alexandria, Va. Josh Dersch can have one for his home and for work. BTW, about the other nice system noted here, I was hoping the 11/20 would stay off the radar and not go for a zillion bucks, so much for that idea. At least I have the means to go to Tucson and get it if I'm nuts and go for it. Thanks Jim

9 years, 6 months

Rescue Fwd: Atari 1040ST (w/Hybrid Arts, Apple 7100AV (w/Digidesign) Utah

by jfoust＠threedee.com

A rescue available... contact Ric directly below. - John >From: Ric Chitwood <dancetech at comcast.net> >Subject: Atari 1040ST >Date: Mon, 18 Jul 2016 10:56:05 -0600 > >I have a fully functioning Atari 1040ST with monitor in the original boxes that I would like to donate. >It also has the Hybrid Arts Smpte Track hardware and software included. > >I also have a fully functioning Apple 7100AV computer with monitor and Digidesign sound card and software floppy discs. Are you interested in these computers or do you know of someone who is? > >Ric Chitwood >Pleasant Grove, Utah

9 years, 6 months

Wiring Regulations. RE: Cray J932SE (was Re: Straight 8 up on Ebay just now)

by dave.g4ugm＠gmail.com

In the UK we have, for DOMESTIC premises something call "Part P" > -----Original Message----- > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mouse > Sent: 19 July 2016 17:47 > To: cctalk at classiccmp.org > Subject: Re: Cray J932SE (was Re: Straight 8 up on Ebay just now) > > >> [...electrical wiring...] > > This very definitely is an area where, if you're not 100% comfortable > > with t$ > > Also, know your own limits. A depressing number of people think they're > more competent than they are. > > For example, I once had a neighbour who replaced an outlet in his kitchen. > Turned off the breaker, removed the old one, put in the new one, all very > nice. Turned the breaker for that circuit back on and popped the service > main breaker. > In the UK we used to have an inspection regime. You did the work, they would inspect. These days, for DOMESTIC premises we have something call "Part P" which limits what a householder can and cannot do. So you can generally do "like for like" replacements, add additional outlets where permitted and one or two other things. Originally all work in Kitchens was defined as "Special" and was notifiable, but this was modified so that is no longer the case. So as the above is a "like for like" replacement, I believe it is currently permitted in the UK. Of course in a Museum, or even a Scout Hut, provided it does not share a supply with residential premises then any one can do the Work so long as it is later inspected..... ... the problem with Part P is that it encourages a "tick box" approach and the Electrician who replaced my "Consumer Unit" (distribution panel) With a new one with multiple RCD's which tripped suggested it would be simpler to re-wire rather than fix the existing wiring. This sort of approach seems common. The actual fault was that I have a pair of linked smoke detectors, and one was connected via one RCD, the other via a different RCD. The connection between the two was sufficient to cause an imbalance. I replaced them with wireless linked smoke detectors and all works well.... > When I investigated, it turned out the new outlet still had the bridging piece > that shorts together the hots for the two outlets, and this was a kitchen > outlet and thus had separate circuits for each half (and, as is often the case, > they were on adjacent fingers in the breaker box and thus on different > phases). So, of course, the new outlet shorted the two hot phases together. > > He didn't have the experience to recognize that those shorting pieces exist, > to realize that having four conductors instead of three coming to the outlet - > or its being a kitchen outlet - likely means the two halves are on different > circuits and thus likely different phases, or the electrical understanding to put > those facts together. Which wouldn't've been a problem, except that he > thought he was fine - he didn't bring me in until the main service breaker > blew. (He did, fortunately, have enough sense for that to tickle his > "something I don't understand happened, call for help" reaction.) > > I've been doing electrical work since I was maybe ten or twelve, when I > helped my parents wire the house they were building. (My father inspected > my work first; then, this being de rigeur there-and-then, it was inspected by > a suitable authority. Only then was it energized.) I don't hesitate to do > routine house electrical work, maybe even installing 30A outlets (though I'd > make sure I looked up the appropriate gauge of wire, and probably then > used the next larger gauge). But I'd call in someone more experienced for > something well outside my own experience, like (say) dealing with 600/600 > service. > > I would say that, if you don't have a good deal of experience, find someone > who does to look over your work before you energize it. > Indeed, some jurisdictions require that for work done by unlicensed persons > - or at least used to, and I would assume some still do. Even if yours doesn't, > it strikes me as the smart thing to do. > > /~\ The ASCII Mouse > \ / Ribbon Campaign > X Against HTML mouse at rodents-montreal.org > / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B Dave G4UGM

9 years, 6 months

Reproduction micros

by jnc＠mercury.lcs.mit.edu

> From: Paul Koning > The article, as usual, talks about a whole bunch of things that are > much older than the author seems to know. "The two most common things in the universe are hydrogen and stupidity." OK, so technically it's ignorance, not stupidity, but in my book it's stupid to not know when one's ignorant. > RISC, as a term, may come from IBM, but the concept goes back at least > as far as the CDC 6000 series. Hmm; perhaps. I always felt that RISC meant 'making the basic cycle time as fast as possible by finding the longest path through the logic - i.e. the limiting factor on the cycle time - and removing it (thereby making the instruction set less rich); then repeat'. (And there's also an aspect of moving complexity from the hardware to the compiler - i.e. optimizing system performance across the _entire_ system, not just across a limited subset like the hardware only). As I've previously discussed, RISC only makes (system-wide) sense in an environment in which memory bandwidth is plentiful (so that having programs contain more, simpler instructions make sense) - does that apply to the CDC machines? > Pipelining, to the CDC 7600. Didn't STRETCH have pipelining? Too busy/lazy to check... > And if you equate RISC to load/store with simple regular instruction > patterns, you can probably go all the way back to the earliest > computers Well, I'm not at all sure that load-store is a good indicator for RISC - note that that the PDP-10 is load-store... But anyway, moving on. One of the books about Turing argues that the ACE can be seen as a RISC machine (it's not just that it's load-store; its overall architectural philosophy is all about maximizing instruction rates). Noel

9 years, 6 months

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