test-drb December 2007

test-drb@ccmp.vtda.org

215 participants
420 discussions

by jos.mar＠bluewin.ch

Does anyone know what a speedgrade an amd9016e DRAM chip is ? Google gives one million resellers and no datasheets. Suggestions as to why replacing said am9016epc with a mcm4116bp20 does not work, are also welcome. Jos

16 years, 12 months

Probably OT - eBay object - what the devil is it?

by mike＠brickfieldspark.org

Looks like a test head although all the ones I ever worked on had a large hole in the centre for probes. It does have printed on it "Testhead side" bit of a give away. Mike > Message: 1 > Date: Fri, 21 Dec 2007 06:33:34 -0800 (PST) > From: Mr Ian Primus <ian_primus at yahoo.com> > Subject: Re: Probably OT - eBay object - what the devil is it? > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> >> >> What on Earth is this? >> >> 110206772756 > Wow. That is unusual. Never seen anything like that > before. It's pretty though. Would probably make a nice > clock... > > -Ian >

16 years, 12 months

5.25 drive with sector output

by ajp166＠bellatlantic.net

> >Subject: 5.25 drive with sector output > From: dwight elvey <dkelvey at hotmail.com> > Date: Sat, 22 Dec 2007 09:43:43 -0800 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > > >Hi > Were there any 5.25 drive made with sector pulse output? >I'm working on a controller for my Polymorphic. I have not >software to run the board so I'm decoding the Z80 code >that runs in its firmware. Yes, every one made. Sector pulse is the same ass index on 5.25" drives. aqn example controller that uses that is the NorthStart MDS. > I see that one of the signals from the drive is the sector >signal. I know that the SA801 could be configured for >32/16/8 sectors and produce a sector output signal. Still requires hard sector media. > In any case, the code seems to be looking for the sector >signal at one point. > The next question is, do the older drives have a filter on >them such that they would not output the index along with >the sector pulse? No.. But some of the old 8" had the index on the inner radius and the hard sector holes at the outer radius making for two seperate signals. Allison > The drive I'm planning on using is an old Qume drive with >a IBM lable on the front. It is a QUMETRAK 142. It is >good to work on because it is all descrete parts and >TTL ( some analog IC's as well ). Still, if they have a >filter on the index, I should be able to modify it. > I only see one pot in that area of the board and I suspect >that it is for the pulse witdh of the index. > If there is no filter, I should be able to make an external >sector separator. >Dwight > >_________________________________________________________________ >i?m is proud to present Cause Effect, a series about real people making a difference. >http://im.live.com/Messenger/IM/MTV/?source=text_Cause_Effect

17 years

Yet another VT-100 emulator

by tsw-cc＠johana.com

On Thu, 20 Dec 2007 13:26:24 -0200 "Alexandre Souza" said: > > I think this project is excellent and a kick-ass way to use spare old > > hardware lying around (which is more likely to have a working 25-pin > > serial port than any modern machine). I love this project. > Although there are cheap CF cards today, it would be a hit if it could > be ROMable and put in place of BIOS chip :o) If you can still find them, ancient XT motherboards ought to be just right for this type of service. Just get an old video board (will it work with a CGA board?) and a serial I/O card and plug in the "extra" bios chips for the emulator. Of course, several options could be added: 1) Support for a character based printer (both serial and parallel) 2) Some sort of scrolling (got to use that 640k of memory somehow!) 3) Color support (if you got a CGA card, use it!). 4) Provisions for 40 column mode (so you can use the RS-170 output to a TV set) 5) Add a network card for a telnet client (probably a bother since there are so many network cards) The best part is that when you turn the machine on, you get instant terminal. None of this silly operating system stuff. ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

17 years

5.25 drive with sector output

by cclist＠sydex.com

> From: dwight elvey <dkelvey at hotmail.com> > Were there any 5.25 drive made with sector pulse output? > I'm working on a controller for my Polymorphic. I have not > software to run the board so I'm decoding the Z80 code > that runs in its firmware. I can ever recall having seen one, although that's not saying that there never have been any. It would be easy enough to make a "index/sector" detector by using a one-shot whose period is set to more than half, but less than the time between sectors. Since the index is placed about midway between two sector pulses, you'd generate an INDEX if you received a pulse and the one-shot hadn't yet reset. Sector outputs would simply be the output of the one-shot, perhaps run though another one-shot or ANDed with the original to provide a pulse of determinsitic length. --------------------- Which brings me to a related topic that might interest some... I'm now beta-testing my "hard-sector synthesizer". It's all coded into a 8-pin PIC 12F629. It operates as follows: 1) For those not necessarily caring about hard sector diskettes, it can function as a READY/ generator--after 3 successive index pulses, the PIC generates a DRIVE READY/. Missing a pulse after that within a 262msec window causes READY/ to be deasserted and the cycle to repeat. Works for both 300 and 360 RPM drives. 2) For those interested in hard-sector generation, the PIC will synthesize index signals for 300 RPM 10 and 16 sector diskettes (selectable by grounding a pin on the PIC) and 32 sector 360 RPM diskettes. The choice between 300 and 360 RPM is made automatically by the PIC based on the drive spindle speed. 3) If a hard-sectored diskette is inserted in the drive, the PIC simply passes the index pulses along. 3) Index pulses are normalized to 1 msec width. Many 3.5" drives and several later 5.25" drives output very long index pulses that need to be pruned back. 4) Calculation of the position of sector pulses is based on the time of the previous disk revolution to about 0.15 percent (I can improve on that if needed). Since the computation is performed for every disk revolution, drift should not be a significant problem. The whole thing is self-contained; no external crystals, buffers, etc. are required; only a +5 supply and a pullup (470-2.2K would probably be fine) on the INDEX/ line coming from the drive. You could probably stick the PIC in an 8-pin socket and "dead bug" it into your system if you wanted to be crude. The PIC can sink 25ma per output. Here's the catch: I'll send out object (and source, if requested), but I'm not going to send out PICs or program them for requestors. I expect that there will be a couple of software updates and I don't want to deal with the hassle of updating everyone's PIC. PIC programmers can be constructed or purchased very inexpensively and there are several free programmer packages out there. PICs themselves are dirt-cheap. I'm not going to post the code to a web site until I'm happy with it-- otherwise, I fear that intermediate versions (i.e. buggy) will start ciculating and I'll never hear the end of things. Drop me a private email if you're interested. Best regards, Chuck

17 years

5.25 drive with sector output

by aek＠bitsavers.org

A quick scan of the Qume 242 maint manual from bitsavers shows there is no separate sector signal. The Shugart 455/465 manual talks about a combined index/sector signal. Looking at the northstar controller, they just refer to the incoming signal as 'hole' and decode it in the controller.

17 years

OT sockets for Nixies

by dkelvey＠hotmail.com

> From: tpeters at mixcom.com > > Please send schematic, thanks. Who makes the MC34063? Something I could get > at DigiKey or Mouser? > I did some reading last year and I read something about driving Nixies with > DC, is that what's usually done, rather than AC? > Yes, they use DC, not AC. You could use just rectifying 120 AC. That will give you just about 170Volts DC after filtering. I suspect that the voltage could be the same tolerance as the AC lines. I'd recommend using an isolation transformer. Some come with taps to raise or lower the voltage about 10% as well. It just has to be enough to fire. I doubt it needs to be to exact. Dwight _________________________________________________________________ Don't get caught with egg on your face. Play Chicktionary! http://club.live.com/chicktionary.aspx?icid=chick_wlhmtextlink1_dec

17 years

The 2N2/256-BSCP [was: Homebrew Drum Computer]

by cclist＠sydex.com

From: Dave McGuire <mcguire at neurotica.com> > > On Dec 21, 2007, at 2:07 AM, dwight elvey wrote: > > As a cheaper alternative to a tunnel diode, do a search for > > a Lambda Diode. I used one of these circuits once to make an > > oscillator that ran at over 100MHz. > > Oh my, there IS an almost-equivalent-to-a-tunnel-diode circuit! That > looks really, really neat...I will have to play with that! I don't know if Lambda diodes would meet the 1965 test. Gunn diodes (another possibility) might, however--invented in 1963. Cheers, Chuck

17 years

The 2N2/256-BSCP [was: Homebrew Drum Computer]

by ajp166＠bellatlantic.net

> >Subject: Re: The 2N2/256-BSCP [was: Homebrew Drum Computer] > From: "Roy J. Tellason" <rtellason at verizon.net> > Date: Sat, 22 Dec 2007 01:00:25 -0500 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >On Thursday 20 December 2007 19:05, Chuck Guzis wrote: >> > From: Dave McGuire <mcguire at neurotica.com> >> > >> > I'd love to find a huge stash of a few thousand new-old-stock tunnel >> > diodes. :-( >> >> You'll kindly observe that I had the good taste not to also mention >> Shockley diodes, which, to the best of my knowledge, are really >> unobtainium. > >Are those what were also referred to at one point as 4-layer diodes? If so, >it's possible to simulate them with a complementary pair of transistors and >not all that many other parts. Shotkey diodes are common. Aka 1n5711. Widely used in Rf and microwave. They are low capacitance fast switching with low threshold. Allison >> American Microsemiconductor still offers a selection of tunnel (Esaki) >> diodes, for as cheap as $9 the each. >> >> http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html > >Hmm. :-) > >> I suspect a clue to the high prices is the "JAN" labeling on some of >> the parts (i.e. military and aerospace application). > >Could be. > >> I have a copy of the GE tunnel diode handbook around here somewhere >> (as well as about a dozen or so NOS diodes in my hellbox) that shows >> all manner of logic circuits constructed with the little beasts. > >I'll have one here: > >http://www.classiccmp.org/rtellason/books/GE_TDM.pdf > >as soon as the upload completes (which will take a little while even with my >DSL connection). It's a 100-page PDF file. > >There _will_ be a "tech books" page supporting the stuff there at some point, >when I can get it done. I'm still in the process of plowing through several >thousand files of "stuff" that I've accumulated over the past few years, >editing some stuff, tossing out some duplicates, and trying to organize >what I'm keeping to be accessible through my local HTML tree. Once I get >that mostly done I'll pull a tech books page together out of it. > >> I've never even breadboarded any of them, but the power requirements >> look very modest. > >I picked up a couple of them once on Canal Street in NYC, but that was a long >time ago. > >-- >Member of the toughest, meanest, deadliest, most unrelenting -- and >ablest -- form of life in this section of space, ?a critter that can >be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" >- >Information is more dangerous than cannon to a society ruled by lies. --James >M Dakin

17 years

Slightly OT: TQFP mounting

by aek＠bitsavers.org

Two approaches that I've seen for conventional soldering iron mounting involve what I'll call "flood and suck" that involves covering all of the leads on one side of the QFP on the PCB with solder and then using a solder "sucker" (such as a Soldapullt) to remove the excess. The other approach uses solder wick (solder removal braid), laying the braid over the QFP leads and PCB and heating and applying solder *through* the braid to the leads. -- I've used "flood and wick" successfully applying liquid flux before the "flood". I suspect soldering through braid accomplishes the same thing.

17 years

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test-drb December 2007