test-drb

test-drb@ccmp.vtda.org

101090 discussions

by compoobah＠valleyimplants.com

> Is there a > good tutorial somewhere that explains how capacitors are used for > decoupling and smoothing? (I've checked some obvious sources, but I > need more detail, like if you connect a cap to a +5 source and ground, > why doesn't it just discharge completely ...) > Look at a book dealing with the design of PSUs, or a introductory electronics course. The basic rundown is this: Capacitors and inductors have reactance across them when fed A.C. Reactance is an opposing force that works against the flow of current, in this respect it's similar to resistance, but resistance is the same across all frequencies, reactance varies (for a given reactive load, X(L) (inductive reactance) goes up as frequency increases, X(c) (capacitive reactance) goes down. Impedance is the combination of reactance+resistance. For a DC supply with ripple, you can think of it as 2 mixed components: a DC component and an AC component. The capacitive reactance is chosen to present a low impedance path to the AC component so it travels through the capacitor rather than into the chip. Inductive reactance figures in because (as mentioned) the traces have inductance, and the capacitor also has inductance (so a large capacitor to smooth a high-frequency AC component might not be the best choice- all of that metal provides inductance that opposes the flow of the AC component). Help any?

18 years, 11 months

crimp-on D-sub pin removal

by compoobah＠valleyimplants.com

> Nowadays I might consider making yet another adapter and rewire the > modular side by using a cat5 patch cord and a dual modular jack, wiring > the jack with the crosswires as necesary. requires very little by the > way of tools, and keeps everything else original. I would have considered that had these been anything special, but I got a bunch of these adaptors from my dad's dental office when they were moving off of their Xenix system (with the Xenix system as well). They are not wired to any standard I know of, and they don't even seem to be wired to the same standard within the lot. I remember fervently wishing that they had used a MicroVAX instead of a PC with SCO. I also wished that I had been paying attention when they were getting rid of the Altos, but that was when I was in 4th grade.

18 years, 11 months

crimp-on D-sub pin removal

by compoobah＠valleyimplants.com

I am somewhat flummoxed- I have a 8-pin modular to DB-25 adaptor that I need to move some pins on to make if functional with a 3B2 machine, but looking at the unused connector positions I can't figure out what the retention device is for the installed pins to remove them. It doesn't look like a Molex-style clip coming from the pin (2 pins are uninserted) and there doesn't seem to be any catches molded into the plastic. Any pointers on how to pull these pins with standard garage tools?

18 years, 11 months

crimp-on D-sub pin removal

by compoobah＠valleyimplants.com

> Only if your garage comes standard with the D-series pin puller tool. > :) > > If you've seen the tool for some variant of molex connector, you've > seen > the principle: a thin-walled split tube which slides down around the > pin, inside the socket, and shoves the plastic retainer bits out of the > way. > > For a picture: > > http://www.tecratools.com/product1199.html > > De The picture didn't help much, but the basic description did (I've never used a Molex pin removal tool, every Molex I've worked on has succumbed to a dental pick in short order). It is possible to remove these with basic garage tools: all you need are a small piece of thin sheet aluminum and a moderate precision 5/64" metal dowel- in short an aluminum soda pop can and a 5/64 drill. Form the aluminum into a tube with a slot suitable for 24 ga wire, put around the pin, pull out- all in less time than it takes to drive to the semi-local electronics store.

18 years, 11 months

VCF Midwest 3.0 thoughts

by ISC277＠CLCILLINOIS.EDU

I had an excellent time this year as usual, even though we initially had some unforseen problems getting rolling toward Purdue. Lots to see, and I had a fun time socializing(and on occasion brainstorming) with those I don't see nearly often enough. The speakers were great and very entertaining, and Rick did a great job coordinating dinner for Saturday night. As an exhibitor, I have to say that the turnout was way better than I thought, especially on Sunday. Thanks to everyone involved for making this not only a success but an entertaining endevour as well. Looking forward to 4.0! Julian

18 years, 11 months

LEO (1950)

by RodSmallwood＠mail.ediconsulting.co.uk

I happened on the program by chance. It might have been called Disappearing Britain. A lot of it was contemporaneous and could have been a Lyons publicity film. (or at least bits of one). I suspect our friends at the National Film Archive might know. I inadvertently made an ambiguous statement. By commercial I meant its use, not its availability for sale. Where would you start to design such a thing? Valves yes.. 12AT7 Bistables as binary counters. Neon devices such as dekatrons as decimal counters. RVL (Resistor Valve Logic). Storage = Ferrite Cores, Tape, Drum possibly. I once saw a Univac FAST RAN Drum memory. What a lump!!! Rod -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Jules Richardson Sent: 16 July 2007 22:45 To: On-Topic and Off-Topic Posts Subject: Re: LEO (1950) Rod Smallwood wrote: > I just caught a part of a TV program showing pictures of and the use > of a computer called LEO. That wasn't the James May thing that aired last Tuesday was it? I think it was something along the lines of 'the history of science', and I wondered what they'd show for origins of the computer - sadly I wasn't around when the show was on though to see. > Anybody know of another real commercial electronic computer before 1950? Hmm, the Ferranti Mark 1 (based on the Manchester Baby) was a commercial machine and built around that same sort of time. I'm not sure if the Ferranti machine was the first to be sold to someone (rather than being used in-house) or whether the LEO was. (Actually, I'm not sure if LEO I was ever used outside of Lyons - I think it may have been the later LEO II that was their first true commercial machine) cheers Jules

18 years, 11 months

1966 Mag: Build NE-2 Neon Bulb Computer - scan available

by James＠jdfogg.com

> Subject: Re: 1966 Mag: Build NE-2 Neon Bulb Computer - scan available > > > It relies on matching the neon bulbs. > > Ha! Matched for how long? After a month, I bet no two matched > ones are matched anymore! > > At least the little voltage regulator tubes (0D3 and friends) > age better. Would zeners be a better choice?

18 years, 11 months

Wanted-VAX and items

by starmaster＠gmail.com

I am looking for a Micro Vax (or any VAX) and/or materials/literature on them. I live about 60 miles south of Denver, and do not have many $$ to invest, but will do what I can. Anyone have any they are willing to part with? I would also dearly love any old Commodore equipment/literature as well! Thank you David

18 years, 11 months

Vol 47, Issue 28, message 10, Subject: LEO (1950)

by mike＠brickfieldspark.org

> I just caught a part of a TV program showing pictures of and the use of > a computer called LEO. > It was made by and belonged to a UK company called Lyons. > They imported and sold tea, ran a chain of tea shops and restaurants, > made and sold ice cream. Leo eventually became ICL, I worked for them (ICL) on LEO III-26 at Charles House in London on payroll and utility billing, my experience was on Ampex TM2's & 4's which the Leo's uesd. The "scope" was on the engineers panel and was for monitoring the memory, it displayed as blocks of 4 bits - 0000 0000 0000 - forget how many coloumns, in a strange variant of hexadecimal, but the days before hexadecimal became the norm. There is an interesting website for LEO's at - http://www.leo-computers.org.uk/pageone.htm - including all the installations.

18 years, 11 months

LEO (1950)

by RodSmallwood＠mail.ediconsulting.co.uk

I just caught a part of a TV program showing pictures of and the use of a computer called LEO. It was made by and belonged to a UK company called Lyons. They imported and sold tea, ran a chain of tea shops and restaurants, made and sold ice cream. I should know, my father worked for them and we had our own ice cream freezer just like shops. Boy were we popular in the summer.!! Any way LEO (Lyons Electronic Office) took four years to build and was up and running in 1950. They showed a large room with closed racks, a console with meters and a scope of some sort. Also a punch and printer machine room. Two applications were featured. A tea blending system and a stock control system for the tea shops. The tea shop application was telephone to punched card in real time. Each teashop had a phone in time slot. >From there it printed picking lists, allocated the stock and even did a van route setup with LIFO loading. It must have been all valve and would need cooling. However Lyons was an ice cream company and refrigeration would not have been a mystery to them. To quote an American actor "I have got to get me one of those!!" Anybody know of another real commercial electronic computer before 1950? Rod Smallwood

18 years, 11 months

What AMP connector is this?

by charlesmorris＠hughes.net

As previously posted, I needed a power cable to connect my 11/23+ chassis to the power controller. The controller end was an AMP Mate-n-Lok and so is the one on the switch board at the front of the 11/23+. Thanks to Vince for the Mouser part numbers. But the connector at the rear chassis is NOT the same. Here is a picture of it (to the left; the Mate-N-Lok is on the right): http://tinypic.com/view.php?pic=6csdoiq The (DEC) cable is marked "70-18384-03 Rev A" and that connector "AMP-2" and "CPH-2". I just made a longer cable with a Mate-N-Lok on both ends, and ran it directly from the switch board to the power controller. Anyway I'm still wondering which connector I could have used, or if this is a previous-owner modification. thanks CHarles

18 years, 11 months

Omnibyte OB68K/VME1

by lee＠geekdot.com

Omnibyte OB68K/VME1 I'm looking for any information on this board. This is a 68000 based 6U VME card and not the similarly named multibus card. Cheers. Lee.

18 years, 11 months

hp tape inventory

by Robert.Smith2＠robins.af.mil

What is the possibility of getting a copy of a Punched Tape.....( 92060-16044 !DSKUP OFF LINE DISC BACK UP )? Robert Smith Process & Support Section Avionics & Instrument Division 402 EMXSS/MXVOPB(MAIPB) Robins AFB,GA (478) 327-8669 DSN 497-8669

18 years, 11 months

Lilith computer running !

by aek＠bitsavers.org

> Which means that there is at least one machine with a complete set of > microcode and higher layers avaliable. Great news! > with at single RS232 channel, no software and a flat directorystructure > with over 500 entries, this looks also to be quite a task. By 'no software' do you mean no development tools? If there is some way to type out the contents of a disk block, you can slowly dump the whole disk. Binary dumps of all the files could be automated if there is a file dump program. > It does have ethernet, but it is the very old ( first ?) 3MB standard. The orig was roughly 3mbits, with 256 device addressing. The specs for what PARC developed exists, though I'm not sure that they exactly copied the design having never seen it.

18 years, 11 months

Alto emulator progress

by aek＠bitsavers.org

http://pullmoll.stop1984.com/alto/ Juergen has made a lot of progress in the past month. There are some small movies up now of the simulation running games with user loaded microcode.

18 years, 11 months

Free Commodores near Seattle (Seabeck), WA

by tosteve＠yahoo.com

Do not email me, see email address below: I have several old Commodore computers that are headed for the junk-heap unless I can find an appreciative collector. I have two VIC 20's, at least two C64s, and one C128. I don't know if ANY of them still work. I think I have some Commodore peripherals too. There may be a Commodore printer as well. I want nothing for them except shipping. If you are interested - or you know someone who is, let me know and we will work something out. Bill Sipple sipplewg at wavecable.com Seabeck, Washington, USA (98380) --------------------------------- Sick sense of humor? Visit Yahoo! TV's Comedy with an Edge to see what's on, when.

18 years, 11 months

neon glow lamps (was TTL homebrew CPUs)

by dkelvey＠hotmail.com

>From: Brent Hilpert <hilpert at cs.ubc.ca> > >dwight elvey wrote: > > > > As a note on the dekatron, these were used in some of the early > > HP counters. They were used as the first, or highest frequency, > > state of the counters. They were quite fast! > > Dwight > >I beg to differ on this. I have a couple of dekatron counters and they >only seem to be good to some 10s of KHz (unless of course, you mean that >that >was pretty fast for the time). Interestingly, one of these counters uses >two >types of dekatrons, the only obvious difference between them being the >colour >of the glow and the part number. The ones in the slower speed decades are >the >usual neon glow, in the higher speed decade a purplish glow (xenon?). I >presume >the purplish glow gas ionizes faster than neon. >I should try to ascertain more accurately the max rate of the purplish deks >but haven't yet as one of the two in the unit is failing. > >I haven't seen dekatrons in HP counters, I believe their first counter was >the >524A and, unless it was radically different than the 524B/C/D, didn't use >dekatrons. Certainly the rest of the 520 series was vacuum tube flip-flops >(AC-4 modules). Hi Bret I recall that is was an HP counter. I don't recall the fastest count but it was on the order of either 10KHz or 100KHz. I don't think it was less then that but it may have been 1MHz. I recall that like many of the HP counters of the time, the other decades were the inline 10 ea bulbs. I don't recall if these were neon or incandescent but I think they were neons driven by dual triodes. I do believe that the ring counter did have a purplish glow. Dwight _________________________________________________________________ http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migrati…

18 years, 11 months

Lilith computer running !

by jos.mar＠bluewin.ch

My interest in the Lilith computer has been restarted after some recent post to a.f.c. ( what a mess a.f.c. is...) I put in some extra effort and was rewarded with a Lilith that booted up into its Medos OS ( version 5.2) The last time this particular machine booted its OS was in 1990 . Which means that there is at least one machine with a complete set of microcode and higher layers avaliable. The machine remains VERY temperamental : Most attempts to boot end in disk softread errors, resetting the Lilith involves power cycling ( I looked for signs of a startupcircuit, could not find any ) Probably some diskplatter / head cleaning is due, not something I look forward too. And then there is the task of rescuing the data : with at single RS232 channel, no software and a flat directorystructure with over 500 entries, this looks also to be quite a task. That's right, the Lilith does not have a hierarchical filesystem ! It does have ethernet, but it is the very old ( first ?) 3MB standard. AFAIK it cannot be interfaced to something more recent. Jos

18 years, 11 months

MODCOMP II Revisited...

by lbickley＠bickleywest.com

My excitement over getting my MODCOMP II running in June (reference post attached) - was somewhat "premature". The MODCOMP II performed well - and then started having intermittent failures. I observed that many of the failures seemed to be the result of badly seated chips. I thought that a bit strange, since I had checked them all as part of the restoration process. As time went on, the system became even more dysfunctional - until it wouldn't run even the most rudimentary programs. I checked with a former MODCOMP hardware support person - and he asked: "What brand were the failing chips you've found so far?". I hadn't even thought about that. He said "Let me know after you check - and I wouldn't be surprised if they were all TI (Texas Instruments)". I did check - and virtually 100% were TI chips. Factoid: Many TI chips produced during 1975-77 period had very thin "legs" and poor tinning. When they were wave soldered, the solder offered them protection. However, when they were socketed (as in the MODCOMP) they had very little protection from the environment. They would rust and eventually fail. He suggested that I just replace all the TI chips in the MODCOMP if I wanted a reliable system. I decided that was too "radical". So armed with a logic analyzer and scope, I began to debug the MODCOMP - one chip at a time. After finding 20 or 30 bugs - ALL of which were TI chips - I finally "relented". I have now replaced about one hundred and fifty TI chips in the Modcomp's CPU and memory planes. I'm about 3/4 of the way through the process - and the MODCOMP is becoming very reliable. It will run basic memory diagnostics by the hour without failure. Final thoughts: The "badly manufactured" TI chips turned out to be a lot more fragile than I had originally supposed. When I removed many of them from their socket, their legs would simply fall off. It wasn't unusual to have two or three legs fall off one chip! Some were incredibly rusty over their entire surface - which wasn't at all obvious looking at them from the top. The MODCOMP sockets were "good news - bad news". Bad, because the sockets exacerbated the TI chip manufacturing issue - and good, because they made the chips easier to replace! Regards, Lyle ---------- Forwarded Message ---------- Subject: MODCOMP II Rescue Revisited... Date: Monday 04 June 2007 21:06 From: Lyle Bickley <lbickley at bickleywest.com> To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> A number of you probably remember me "announcing" in Jan, 2007 that I had rescued a MODCOMP II/12 from a lab here in Silicon Valley. The link for that is below (sorry, it's slow - the pictures are large). http://bickleywest.com/modcomp.htm After a lot of work cleaning up both the CPU and I/O chassis I began checking out the system. It turned out that the I/O chassis was in pretty bad shape. I went back to the lab facility where I found the MODCOMP II - looked through several more buildings - and found another lone MODCOMP II I/O chassis. I went through the "salvage" process again - and finally picked it up about a month ago. It was in a lot better shape than the original I/O unit. And the really great news - it was an identical configuration to my original I/O chassis. After cleaning it up, doing all the usual capacitor, power supply checking - I powered it up - and everything "looked" good - and no bad "cooking" smells ;-) I cabled up the CPU and I/O unit, powered 'em up - and to my amazement the front panel controls seemed to work O.K. I then did the usual hand memory tests - and core memory worked O.K. every location I tested. I then wrote a bunch of small diagnostics (in machine code) - and found that I/O was not easy to code - but I did enough to check that the console in/out ports worked O.K. Today I loaded diagnostic monitors, and diags - and most of the system - including I/O is working! The really good news is that all 64K (words) of core memory passed the long manufacturing memory diagnostic - which even tests for "hot cores" failing. It's been months in the making this critter come alive - but it sure feels great when the diagnostics tell you that you are on the right track :-) Cheers, Lyle ------------------------------------------------------- -- Lyle Bickley Bickley Consulting West Inc. Mountain View, CA http://bickleywest.com "Black holes are where God is dividing by zero"

18 years, 11 months

JFETs in logic circuits

by cclist＠sydex.com

Someone, about a week ago, asked about JFET use in logic circuits. It turns out that the questioner was a bit ahead of the times. There's a relatively new device called a G4-FET that's made up of a MOSFET and a JFET, has 4 gates and can be used to make a 3-input NOT- majority logic element. Read about the construction here: http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/10067/1/02-2177.pdf And its use in logic here: http://www.freshpatents.com/Universal-programmable-logic-gate-and- routing-method-dt20070111ptan20070008013.php Cheers, Chuck

18 years, 11 months

Looking for something to put in this space (PDP-11)

by charlesmorris＠hughes.net

Here's a pic of my PDP-11/23+ system with two RL02 drives. There is an empty space about six inches high below the second drive, as you can see. (In the rear is a power controller and a panel with 16 serial ports, although I don't have anything to hook up to them for now). http://i18.tinypic.com/4pc8sux.jpg I'm looking for either a blank panel to cover the hole, or maybe an interesting device I can fit there, if anyone has a suggestion? thanks Charles

18 years, 11 months

UK computer history gets new home

by RodSmallwood＠mail.ediconsulting.co.uk

There is quite a lot more of what happened re the Japanese codes in the various books that have been published. The breaking of JN25 by Rochfort to reveal the plan to invade Midway Island and the susequent loss of three carriers by the Japanese has been the subject of books, TV programmes and films. Another coup was the decoding of Yamamoto's inspection plans and the shooting down of his plane at extrame range by US twin engined Lockheed Lightning fighters. Some of the Japanese codes were quite weak due the mistaken belief that the Japanese language and Japanese morse code provided a level of protection. (They didn't!!) As to the Germans. The Abwehr did break the allied convoy code and a forward mobile unit in North Africa had considerable success with Montgomery's radio traffic. They did that is, until overrun and captured. Rod Smallwood -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of William Donzelli Sent: 13 July 2007 00:53 To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: UK computer history gets new home > What gets me a little is the comparative lack of recognition that all > the others working on projects like Colossus have received; Turing > still gets publicity (rightly so), but not much ever gets said about > all the others who were contributing effort and ideas. This is a very common problem, especially when dealing with wartime technologies and who gets the credit. Two of the big factors are state secrecy, and the old saying "the victor writes the history books". For the former, one can look at the breaking of the Japanese codes (purple being the most famous). The Enigma and Lorenz stories are now pretty much out in the open and declassified, but the Japanese stuff is still locked up in secrecy. Under the veil of secrecy, the guys that did the work can not get the credit. For the latter, one can see just how little (almost no) credit is given to the Axis powers. There is very credible evidence that Allied codes were broken during World War 2. It is likely the Germans had some sort of equivalent of Bletchley, but is probably forever lost. The Allies were not about to give credit to the Axis engineers. Many still will not. It is bothers you - then speak up. Give the guys credit. Spread the word. They deserve it. -- Will

18 years, 11 months

VCFmidwest v3.0 begins

by jwest＠classiccmp.org

Greetings folks... from West Lafayette, Indianna. The weather is awesome this morning, the day the festival begins. I arrived around 7:30pm local time last night and met up with Pat. He was able to get me into the exhibit area to set up my HP 21MX. I called a few people to see about dinner/drinks but was unable to rouse anyone by 10pm when I was free. I'm in the hotel room getting some documents together for handouts on the 21MX/E at the show (the poyner article as well as some technical spec sheets). I'll run to Kinkos a few blocks up the street and print them off momentarily. Then it's off to a big breakfast and then exhibit hall. Remember - doors open at 10:30am, speakers at 11am, and exhibits from 2pm to 6pm. I suspect that like in years past, most of us will head out to dinner this evening. Hope to see you at the show! Jay West

18 years, 11 months

Bringing up an Altair 680...

by wh.sudbrink＠verizon.net

I've just been given access to an Altair 680. It seems to be in excellent physical condition (no rust, corrosion, dents... just some dust). Has not seen power in many years. All of the ICs are socketed. Due to the fact that the PS is incorporated onto the main board, I was planning the following: 1) Remove the main board from the case, detaching it from the front panel board. 2) Remove (carefully noting their positions) all of the ICs from the main board. 3) Attach dummy loads (24V light bulbs) to the PS at convenient locations. How many should I use? 4) Attach to AC power in this state. Assuming nothing pops, check DC voltage (voltages?) with a scope. Assuming DC looks good, allow to warm up for a few hours. 5) Scope check DC again. Power down allow to cool for a few minutes. Repeat steps 4 and 5 a few times (3? 4?). 6) If all looks good, reinstall all of the "easy to replace" ICs and do 4 and 5 again. 7) If all looks good, reinstall the rest of the ICs, restore the main board to the case and front panel. 8) Debug any logic problems (dead chips, opens, etc.). Does this look reasonable? Thanks, Bill No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 7/12/2007 4:08 PM

18 years, 11 months

Tandy 1000EX in Craigslist, Morgantown, WV

by us21090＠yahoo.com

I'm not associated with this person. See: http://morgantown.craigslist.org/sys/366079794.html Reply to: sale-366079794 at craigslist.org Date: 2007-07-03, 8:07PM EDT Tandy 1000EX [8086 processor] purchased in 1985, I think. Has dot-matrix printer; mouse; joystick; 1200 baud modem; internal and external 5 1/4-inch floppies plus an external 3 1/2-inch floppy. Monitor and stand. Games and other programs. I hate to just throw it away or e-cycle it. Pic available on request. Make an offer. ____________________________________________________________________________________ Shape Yahoo! in your own image. Join our Network Research Panel today! http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7

18 years, 11 months

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