test-drb September 2010

test-drb@ccmp.vtda.org

163 participants
222 discussions

by ard＠p850ug1.demon.co.uk

As all of us who do hardware repairs know, a multimeter is an essential piece of test equipment. Until a couple of days ago, I used a Fluke 85 (original series). It did what I wanted, there were 2 parts of the design I didn't like, but apart >from that it was great The 2 thing I didn't like were 1) You have ot dispmantle the meter to change the battery, and it's assembeled with self-tapping screws going into the plastic case. I don't know how many insertions they will stand. 2) The most switch used resistive traces on the PCB with a wiping contact to connect them to an analogue input on the main chip. If that wiper didn't make contact properly, it sometimes got into the wrong mode. It owuld even sometimes power itself up (and flatten the battery) when in the off poosition. Anyway, I was using this iustrument on Saturday (actualy for testing the PSU, etc, in an HP2623 graphics terminal) with no problems. I put it away in my tool drawer. On Sunday I got it out for some other tests and discovered the display had failed. It's totally black for half the height, I asusem the liquid crystal material has leaked out (although the glass is not obviously cracked or broken). AFAIK nothing fell on it in the tool drawer (there are no really heavy tools in there anyway), it wasn't dropped, etc. Just one of those things. Alas Fluke say they can no longer supply the display for this insturment as a spare part. Given that I need the standard functions only (including a good continuity tester!), don't need excessive accuracy, and would like to be able to fix it if anything goes wrong, does anyone have any recomendatins? I am not conviced I should buy another Fluke, BTW. Long shot : Does anyone have a defective original-series Fluke 80 with a good display (maybe the ASIC has died or something). I would be interested in buying it. -tony

13 years, 6 months

Evolution of the Apple Mouse

by marvin＠west.net

I saw an article on Mashable with photos of the evolution of the Apple mouse. Kind of interesting. http://mashable.com/2010/09/26/evolution-apple-mouse/ Marvin

13 years, 6 months

IP Fragments - Worth doing, testing strategies?

by mbbrutman-cctalk＠brutman.com

I have been working on my TCP/IP stack for DOS, adding IP fragmentation support. There are not too many more features that I want to add to make it 'complete' before I open source the code and IP fragment support was a big one. I am having a terrible time testing it though. It seems that IP fragments out in the wild are pretty rare. I tried connecting to a slew of remote FTP sites hoping to find one that was behind a really bad network, and thus would have fragments coming from it. No joy. It seems that there are a lot of tricks out there to prevent fragments >from being created, especially when using TCP. The only way I can test the code is to send myself oversized UDP packets. If it works for UDP then it should work for TCP too, but I'd really like to test the TCP path explicitly. Combine the tricks with modern broadband and getting fragments is really difficult. Even on the home network I am having a hard time getting fragments. I put a Linux box between the DOS PC and a Windows machine, and set one of the Ethernet MTUs to 576. Well, that didn't force fragments because the Windows box is too clever. I could start turning everything off in the registry, but I really don't want to get that involved. Off the top of my head I think I am going to have to get another Linux box and dumb that down, if it is possible. Dumbing Linux down to turn off the features and then restoring it to a good state is probably safer/easier than doing it with Windows. Does anybody have a good technique for setting up a simple network that will result in IP fragments of TCP? On a related note, is this even worth it? I don't know of anything that needs to send fragments except for NFS over UDP. There might be other applications that send big packets over UDP but those would be the only class of applications that absolutely require fragment support. With TCP it is nice, but a user should be able to get around any problem by setting the local MTU to 576. Mike

13 years, 6 months

Latest eBay seller BS

by aek＠bitsavers.org

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230532269086 I don't know how he does this, but the auction starting price went up $10 as soon as I started watching the auction. It has happened TWICE now on relists of the same item.

13 years, 6 months

Dealing with heat

by wdonzelli＠gmail.com

> I just sold 30# of aluminum heatsink approx 8" wide x 4" high x 5' long for > $40.00. 9 other identical pieces were scrapped out for about $15.00 each. My > understanding is that they were in the $100.00 + catagory when new. And that sounds like it was for stock extrusions. If you add all sorts of machining so the heatsink actually touches the processor, you can add a bunch more on to the price. Fans are cheap and effective. And the last place *anyone* wants to go is liquid cooling. -- Will

13 years, 6 months

Apple II Killer App

by mardy＠voysys.com

So now that I know that my recently restored Apple II is going to turn into dust in the not too distant future, how can It best be demonstrated to illustrate why it was so awesome back in '78? For example, with an Altair, you can either load Billy's Micro Soft Basic or play "Fool on the Hill" through your AM radio. But what application do you run on an Apple II that epitomizes Steve and The Woz's gift to man kind? -Mardy

13 years, 6 months

OT: Worth exhibiting at Maker Faire?

by evan＠snarc.net

Hi all -- My club (MARCH) is scheduled to exhibit at the inaugural Maker Faire NYC. I'm starting to have second thoughts because we don't "make" anything, we just make old things work again. Who here has been to a Maker Faire event, and if so, would a vintage computers exhibit be well received by the audience?

13 years, 6 months

Evolution of the Apple Mouse

by marvin＠west.net

> Try pricing a big-ass hunk of extruded heatsink some day. > > -- > Will I'm sure this somehow relates to the Apple Mouse, but it will need to be explained to me so I can understand. I just sold 30# of aluminum heatsink approx 8" wide x 4" high x 5' long for $40.00. 9 other identical pieces were scrapped out for about $15.00 each. My understanding is that they were in the $100.00 + catagory when new. Marvin

13 years, 6 months

SPSS for Windows

by charlesmorris800＠centurytel.net

I'm cleaning out the closet and found my V6.1 SPSS for Windows (24 Jan 1995) on eight 3.5" floppy disks "Graduate Pack for student home use only", purchased in 1996. Anyone want it for $5 plus postage from zip 65775?

13 years, 6 months

Ok, gotta show this...

by mdavidson1963＠gmail.com

My latest acquisition (thank you, Stan!). An HP 3000/935 with several drives (all working). Photo links below. http://www.facebook.com/photo.php?pid=5152529&l=4dfb3c29ff&id=734972117 http://www.facebook.com/photo.php?pid=5152533&l=3e032379a3&id=734972117 I'm so thrilled! Mark

13 years, 6 months

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test-drb September 2010