test-drb August 2006

test-drb@ccmp.vtda.org

216 participants
517 discussions

by brain＠jbrain.com

Now that I got Scott's treasure on it's way, here's a few more options. Scott is not eligible :-) Issue 37-136 of Circuit Cellar, plus a few volume 1 (1.6 and 1.8) and volume 2 issues. I regret ditching this, but I never read them, and I can get them via CD if I do want them later. Mixed (16 or so) issues of Popular Electronics from '93 to 99. dozen or so issues of Modern Electronics/ComputerCraft/Microcomputer Journal from '90 to '97. Mostly 95-97 (Microcomputer Journal) No hoarding, first come, first serve, I'm asking only for shipping costs >from Iowa (52402). Anything not claimed hits the recycle bin after a week. Jim

17 years, 11 months

Handwire vs PCBs (was Re: group buy for homebrew CPUs?)

by ethan.dicks＠gmail.com

On 8/14/06, Chuck Guzis <cclist at sydex.com> wrote: > I think the big problem was a shift in thought. Anyone who learned to > solder back in the handwired days remembers being told over and over again > that "Solder does not make a mechanical connection". Or in other words, > good wiring practice demanded that a wire be mechanically attached to its > terminal before solder was applied. Along come PCBs and what's holding > everything together? Solder. My dad (who was a Ham in the 1950s) told me over and over that solder is not a load-bearing material. Of course, given the weight of 1950s components, if you _don't_ make a good mechanical connection first, a solder-only joint is likely to fail eventually. I remember how hard it was to tear apart stuff from those days... I needed a solder gun and a quick hand with the needle-nosed pliers to start to unwind the leads from the solder tabs before the mass of the pliers cooled the joints. OTOH, a technique I've picked up from a co-worker here for nice faraday-cage-type enclosures (for RF-emitting/using projects) is to solder a box from chunks of copper-clad board. It's easy to work with and for stuff that small enough to fit in your hand, *very* strong. -ethan

17 years, 11 months

group buy for homebrew CPUs?

by trag＠io.com

>Date: Sun, 13 Aug 2006 10:09:54 -0400 >From: Dave McGuire <mcguire at neurotica.com> >On Aug 12, 2006, at 4:37 PM, Jeff Walther wrote: >> BGA components have a specification for the clearance between the chip >> package and the circuit board after soldering. I don't think you >> could meet that just by putting the thing in the oven. > > Very true...but I've looked far & wide for a reason for that >specification to exist, and have found none. The only thing I can >think of is the possible flattening out of the balls causing them to >short against adjacent ones...but is that really possible? Not sure. I assumed (certainly don't *know*) that the specification is there because if the chip finishes too high above the PCB, then you didn't melt the balls enough and you may have cold joints, etc. and if the chips finishes too low/close to the PCB, then you've squished the balls too much and they may be in danger of shorting. At the least, it seems to me that if you meet the clearance specification, you're more likely to succeed at BGA soldering without expensive equipment to inspect the hidden solder balls. I could be wildly wrong though. I never carried through with my experimental ideas. Another thought is that if you use the feeler guage idea that I proposed, then you can heat the chip and board more thoroughly without the chip sinking any closer to the board. That should help to ensure good solder joints on the interior balls without allowing the chip to squish to close to the board. I think I was looking into it when the PPC750FX and later the PPC750GX came out and I really wanted to get them onto a ZIF module of the type that plugs into the Beige G3 model Macintosh. But Powerlogix came out with a couple of nice cards, so buying commercial became cheaper and more practicle than trying to do it myself. (Thank goodness!) Jeff Walther

17 years, 11 months

Handwire vs PCBs (was Re: group buy for homebrew CPUs?)

by ajp166＠bellatlantic.net

> >Subject: Handwire vs PCBs (was Re: group buy for homebrew CPUs?) > From: "Ethan Dicks" <ethan.dicks at gmail.com> > Date: Mon, 14 Aug 2006 14:13:09 +1200 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > > >OTOH, a technique I've picked up from a co-worker here for nice >faraday-cage-type enclosures (for RF-emitting/using projects) is to >solder a box from chunks of copper-clad board. It's easy to work with >and for stuff that small enough to fit in your hand, *very* strong. > >-ethan I use that thechnique all the time to build RF assemblies where stray signals need to be bottled up to prevent unwanted signals in the wrong places. the advantage is not only is it a good shield but using scraps (cheap material) you can build custom enclosures for subassemblies. To keep this on topic at least somewhat. Years ago I built a PLL subsystem for a radio with a micro to do the tuning and display chores. The RFI from all that (8748 with led drivers and input controls) was unbearable. Boxed it all up as previously described using copper screen across the display opening and it was reduced to dead silent. Of course the few wires (power, slow parallel digital signal for tuning and switches) entering and leaving had to be properly filtered as well. Allison

17 years, 11 months

group buy for homebrew CPUs?

by trag＠io.com

>Date: Fri, 11 Aug 2006 15:58:16 -0600 >From: "e.stiebler" <emu at e-bbes.com> >Chuck Guzis wrote: >> On 8/11/2006 at 4:37 PM shoppa_classiccmp at trailing-edge.com wrote: > >> I suspect that the legacy DIP stuff will get harder to buy new through >> "normal" channels, given RoHS. In the long run, I suppose we'd all better >> get used to working with surface mount. :( > >Yup, get ready to solder .2 mm balls on 800 balls BGA. >Get your toaster-oven ready ;-) BGA components have a specification for the clearance between the chip package and the circuit board after soldering. I don't think you could meet that just by putting the thing in the oven. However, it might be interesting to get some feeler guages the same thickness as the clearance that that specification calls for, place the feeler guages around the edges of the chip between the chip and the board and then heat the chip and board until the chip presses down on the feeler guages. That *should* give the proper clearance and therefore the appropriate solder ball "squish". I don't know how one reballs BGA components though. Anyone care to explain? Jeff Walther

17 years, 11 months

semiconductor mfr. logos page

by trag＠io.com

>Date: Sat, 12 Aug 2006 20:53:39 -0400 >From: "Roy J. Tellason" <rtellason at verizon.net> >Subject: semiconductor mfr. logos page >To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> >Message-ID: <200608122053.39577.rtellason at verizon.net> >Content-Type: text/plain; charset=us-ascii > >A while back I'd sort of thrown something together with a bunch of logos on a >web pages, and since Jay expressed some interest in that some time back I >uploaded it, but since I wasn't happy about a number of aspects of it back >then I didn't link to it and didn't publicize it. ICMaster.com had a few pages of logos and manufacturers' names in alphabetical order, back when. They seem to have revamped their web site and maybe been taken over by someone else. I can't find their logo pages any more. Anyone else have any luck? Jeff Walther

17 years, 11 months

KVM's

by aliensrcooluk＠yahoo.co.uk

--- jim stephens <jwstephens at msm.umr.edu> wrote: > Don wrote: > > > > > > > It doesn't take long to realize that this is a > non-solution: > > - keyboards are PS2, Sun, USB, ADB, etc. > What does ADB stand for? The reason I ask is that my initials are ADB (my middle name is David), and every time I see it in a message it throws me for a split second. Regards, Andrew B aliensrcooluk at yahoo.co.uk

17 years, 11 months

Pictures of old S-100 cards?

by jcwren＠jcwren.com

I've been putting some S-100 cards on eBay, and I started wondering if anyone was maintaining a database of pictures of old cards. If not, and someone chooses to start one up, anyone is welcome to my pictures. http://tinymicros.com/ebay is where they're located, starting somewhere on page 20 or 21. They're not great photographs, but they're more than adequate to help identify boards and such. --jc

17 years, 11 months

HP 1000 double integer instructions info

by jdbryan＠acm.org

I'm working on adding double integer (32-bit) instructions to the HP 1000 simulator under SIMH. The 1000 F-Series computer came standard with these instructions, and I have documentation on the opcodes used. The E-Series did not have them, but there was a "specials group" product -- HP number 93585A -- that added firmware support for these instructions. However, the opcodes were different from the F-Series opcodes to avoid conflict with other E-Series microcode options. Does anyone have information on the opcodes used in the 93585A product? I have found a reference to a manual, HP number 93585-90007, "93585A Double Integer Firmware Installation and Operating Manual," but I cannot locate a copy. -- Dave

17 years, 11 months

KVMs

by compoobah＠valleyimplants.com

Don intones: > >Is it possible to add a second Crestor/Elite FB? (Sorry, I haven't >poked around inside this box, yet) Nope, UltraSPARC IIi doesn't support enough spare UPA ports. You can get a PCI PGX card if you so desire. Some of the bigger systems that use the full UltraSPARC II or UltraSPARC III with the external UPA/Crossbar controller offered more graphics ports. I think the 60 and 80 did, as well as the deskside beasts (and I suppose you could wedge a few screens into an Ultra Enterprise 10k if you wanted...) Even with the full UltraSPARC implementation, many smaller machines (e.g. Ultra 2) only had one UPA expansion slot for size reasons (and, I suppose, to protect the profit margins of the high-end systems).

17 years, 11 months

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test-drb August 2006