test-drb April 2002

test-drb@ccmp.vtda.org

280 participants
1162 discussions

by ajp166＠bellatlantic.net

Not that many trasistors more like 128 diodes. You would need to know: 1-The switching current for the core: 2-the half select current(related to #1): 3-Time to switch 4-is it a 2d or 3d array(word or bit frame) 5-single sense/inhibit or serperate sense and inhibit lines. Words are driven by the same drivers as an individual bit so that saves parts. Generally there is an array of multiplexed devices to drive the array, for a 64x64 that would likely mean only 128 driver devices (best done as integrated stuff like TI 754xx parts) and a lot of steering diodes. You will need a sense amp per bit and an inhibit driver per bit. Most core systems use a delay line to get the timing as the cycle is RMW (read/modify or rewrite) as core is destructive read out (generally) so you have to write the data back. The time you sense the bit change is tied to the core used and varies some with temperature and current. Also the sense amp must discriminate from noise and a valid pulse related to a bit change. Oh, it will be slow. Most core system were over .5us{500nS} Tacc and Tcy are typically 1.0-1.6us{1000-1600nS} . It's a rewarding task but non-trivial nor small. FYI: you need a heafty low noise multiple voltage power supply to run it. Me, I'm looking at a 16k semiconductor memory replacement for a PDP-8f that is simple. This would be a resource to those that have found an -8 without enough core or to replace bad core. This is of course a IMCFT project. Allison {IMCFT >>> In My Copious Free Time} -----Original Message----- From: Bill Richman <bill(a)timeguy.com> To: classiccmp(a)classiccmp.org <classiccmp(a)classiccmp.org> Date: Wednesday, April 03, 2002 12:58 PM Subject: Core Memory Interfacing? >Right off, let me say that I know next to nothing about the realities of >using core memory. I only know that it looks like pretty cool stuff to >play with. Would I be completely off my tree to try to build a core >memory interface from scratch, assuming I had a pre-strung core frame with >all the cores and wires intact? When I say "interface", I mean basically >something that will let me talk to the core from a PC or from my >recently-completed Mark-8 using TTL or CMOS levels. If I have a 64x64 >frame, would I just need something on the order of 256 driver transistors >(one to drive each of the X and Y wires in either direction) plus some >kind of op-amp or comparator circuit to monitor the sense wire (is there >just one of these per frame?) and determine whether or not a bit has >flipped during a read pulse? Or are there all sorts of ghosts and goblins >lurking in core memory that I don't want to confront? > > > >

22 years, 3 months

Computers Manufactured in 1986^H^H56"

by dquebbeman＠acm.org

> From: Douglas H. Quebbeman <dquebbeman(a)acm.org> > > >> PDP-8e of various forms, Cincinattai Millichron CM2000/2100/2200 to > > ^^^^^^^^^^^^^^^^^^^^^ > > > >Cincinnati Milacron > > Ok, since your so good as to fix the spelling, maybe you > know where oneis? > > I woked with them briefly in '73, never seen them since. Last one I saw was in the Humanities Department at IU, hooked to a CDC 607 tape drive and running one of the first lazer light shows, called Soleil, in 1977. They *may* still have it... or someone associated with the school probably does. Don Byrd was the guy working with it, he's up at some school in Boston now, I think... The PDP-8 clone I'm looking for is the Harris/COPE 1200... -dq -Douglas Hurst Quebbeman (DougQ at ixsnayamspayIgLou.com) [Call me "Doug"] Surgically excise the pig-latin from my e-mail address in order to reply "The large print giveth, and the small print taketh away." -Tom Waits

22 years, 3 months

Soldering and other skills (was Re: QL-Quality (Was: ZX-81 Question))

by philpem＠btinternet.com

ard(a)p850ug1.demon.co.uk (Tony Duell) said: > > Don't eat sandwiches while you're soldering...and wash your hands when > > you're done ;-) Lead in gasoline (petrol over here) was a bigger > > problem. > > But I am not at all convinced that the alternatives that are added to > 'unleaded' petrol are any more healthy... Hmm... Now you've me a bit more to worry about... > > Resin flux is a known carcinogen, so don't breathe the fumes. > > Oh _great_. Still, it's a well-known fact that research causes cancer in > rats :-) ROFL! Theoretically, judging by the amount of solder flux I've inhaled over the past few years, I should be either on my deathbed or have some form of cancer by now... Fact: If I listed every single chemical I've ever exposed myself to, it would probably be long enough such that if I printed it out, it would go to the sun and back... And some of the chemicals on that list: Acetic acid (photographic stopbath) Hydroquinone (photographic developer) God-knows-what (photographic fixer) Acetone (nailvarnish remover) Whatever SRBP board dumps when heated to 180 deg C (toner transfer) Ferric Chloride (PCB etchant) Lead (solder) Rosin (solder flux - Maplin probably don't use it in their lousy "Adepto" solder) Xylene (Electrolube lacquer pen) Mercury (glass tiltswitch) Need I go on? Once again, my philosophy is "Screw it - I'm going to snuff it at some point anyway". And if scraping my fingers (and cutting them) with solderjoints is as bad as breathing in solder fumes, I should REALLY be dead by now... Later. -- Phil. philpem(a)bigfoot.com http://www.philpem.btinternet.co.uk/

22 years, 3 months

"BidsToGo" is places to go, things to do

by webmaster＠bidstogo.biz

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22 years, 3 months

DEC swap meet?(RE: Off Topic? PDP 11 1134/1145's)

by ajp166＠bellatlantic.net

A good choice is the MIT flea, held every 3rd sunday starting April through September. It's in Cambridge MA (nearly Boston.) Allison -----Original Message----- From: John Allain <allain(a)panix.com> To: port-vax(a)netbsd.org <port-vax(a)netbsd.org>; classiccmp(a)classiccmp.org <classiccmp(a)classiccmp.org> Date: Wednesday, April 03, 2002 12:00 PM Subject: Re: DEC swap meet?(RE: Off Topic? PDP 11 1134/1145's) >> Maybe we can get something going up here in New Haven, CT? > >I'm all for something like this. NYC/Boston is my route, so New >Haven is right on it. I've driven as far as Rochester (350?mi) for >such purposes. Washington, DC would be in my range. >Maynard, MA would be a neat choice for historic reasons. > >John A. > >

22 years, 3 months

DEC swap meet?(RE: Off Topic? PDP 11 1134/1145's)

by CordaAJ＠nswc.navy.mil

I'd also be quite happy with Washington DC (It's just an hour or so away from me :-) additionally, it has a number of interesting sites to visit (Smithsonian?) for those who haven't been here before. -al- -acorda(a)1bigred.com > -----Original Message----- > From: John Allain [mailto:allain@panix.com] > Sent: Wednesday, April 03, 2002 11:35 AM > To: port-vax(a)netbsd.org; classiccmp(a)classiccmp.org > Subject: Re: DEC swap meet?(RE: Off Topic? PDP 11 1134/1145's) > > > > Maybe we can get something going up here in New Haven, CT? > > I'm all for something like this. NYC/Boston is my route, so New > Haven is right on it. I've driven as far as Rochester (350?mi) for > such purposes. Washington, DC would be in my range. > Maynard, MA would be a neat choice for historic reasons. > > John A. > >

22 years, 3 months

Computers Manufactured in 1986^H^H56"

by ajp166＠bellatlantic.net

From: Douglas H. Quebbeman <dquebbeman(a)acm.org> >> PDP-8e of various forms, Cincinattai Millichron CM2000/2100/2200 to > ^^^^^^^^^^^^^^^^^^^^^ > >Cincinnati Milacron Ok, since your so good as to fix the spelling, maybe you know where one is? I woked with them briefly in '73, never seen them since. Allison

22 years, 3 months

Computers Manufactured in 1986

by dquebbeman＠acm.org

> Hmmm PDP-1 eh? > > I could emulate it .. ;^> If you do, try separating the graphics display emulator from the computer emulator... then we could use it for yet still other emulated systems! -dq -Douglas Hurst Quebbeman (DougQ at ixsnayamspayIgLou.com) [Call me "Doug"] Surgically excise the pig-latin from my e-mail address in order to reply "The large print giveth, and the small print taketh away." -Tom Waits

22 years, 3 months

WTF?

by fauradon＠beckman.com

I usually don't post from work but this need to be noted and discussed!!! http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1341836302 For those of you who can not check the link out: it's a collection of gaming consoles with a bid of $11,600.00 Yes that's eleven thousand six hundred bucks. Granted it has some nice pieces I can't add it up to that amount. Francois

22 years, 3 months

DEC swap meet?(RE: Off Topic? PDP 11 1134/1145's)

by wilson＠dbit.com

From: "John Allain" <allain(a)panix.com> >> Maybe we can get something going up here in New Haven, CT? > >I'm all for something like this. NYC/Boston is my route, so New >Haven is right on it. I've driven as far as Rochester (350?mi) for >such purposes. Washington, DC would be in my range. >Maynard, MA would be a neat choice for historic reasons. Sounds good to me too, I'm near Springfield MA so I can hit anywhere in NE easily, or eastern NY. John Wilson D Bit

22 years, 3 months

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test-drb April 2002