test-drb April 2005

test-drb@ccmp.vtda.org

269 participants
730 discussions

by andyda＠earthlink.net

> The stock AIM 65 was offered with either 1K or 4K RAM, I bought a 1K > and a guy I knew at Rockwell gave me the other 3K. : That RAM wouldn't happen to be in 2114s, would it? If so, I'd suspect : those early on, I've had more trouble with 2114s than with any other : chip. I've lost count of the number I've replaced (certainly the RAM in : my Commodore 8050, the video RAM in my TRS-80 Model 3, the RAM in my : HP82163 (HPIL video interface)...) : -tony Yep, the RAM is 2114! I swapped the zero page RAM with others in several configurations. Out of 8 RAM how many would you suspect as bad? Could it be all 8, or a significant number such that getting just the right 2 for zero page wold be difficult, maybe I should buy at least a couple just to hope I get 2 good ones to try?! Thanks, AndyD

21 years, 1 month

Questions - Universe/68, HP-9134A,VT420 composite video

by david_comley＠yahoo.com

--- Patrick Finnegan <pat at computer-refuge.org> wrote: > First off, before you go around modifying VT420s, > you may want to test > the Pro first. Yes, the Pro is a complete unknown quantity at the moment. My suspicions about someone messing with the power supply were confirmed when, after removing the already-unscrewed top cover I found a nice green jumper cable across what was left of the fuseholder. I think I will take my time on this one. Perhaps I should make sure I have a fire extinguisher handy as well. > The 'composite' output of the > machine nicely matches > NTSC (RS-170) composite signal specs, so you can > hook the output > directly to a TV with a composite input. Beware If I can ever get the thing to power up I have an old portable TV upstairs I could use - no composite input but I do have an RF modulator I bought years ago. Perhaps that will work. And the VT420 I had in mind needs to be repaired anyway since it screeches at me when I turn it on, so perhaps that's not the best approach. Thanks for the advice. Regards, Dave __________________________________ Do you Yahoo!? Plan great trips with Yahoo! Travel: Now over 17,000 guides! http://travel.yahoo.com/p-travelguide

21 years, 1 month

HP-2116A chassis (or repairing cast aluminum)

by pete＠dunnington.u-net.com

On Apr 17 2005, 7:32, Vintage Computer Festival wrote: > On Sat, 16 Apr 2005, Bob Shannon wrote: > > > I think the actual frame here is magnesium alloy, not aluminum. > > > > Any attempt to weld this might be spectacularly bad idea. > > Listen to the man (with an emphasis on "spectacular" in the true sense of > the word). Probably not, actually. It's hard to get the stuff to burn, and it might well collapse under its own weight before you got it all that hot, at which point you'd probably remove the hot flame and emit a few hot words instead ;-) [1] Yes, the ignition temperature of some magnesium alloys is below the melting point, but you need an *awful* lot of heat to make it catch, not just a high local temperature. You also need an awful lot of heat to sustain it -- remember it dissipates heat readily -- and you need oxygen[2] to keep it going. Under normal welding conditions, the inert gas used for TIG/MIG excludes the oxygen (that's the whole point of the method) and the heat is highly localised, and other techniquesuse much lower temperatures. TIG welding of mag alloys is quite commonplace, and most items of magnesium alloy you'll come across are heat treated during manufacture, at high temperatures. This is not something you can do at home with a paraffin (kerosene) blowlamp, it's usually done in ovens in an inert atmosphere, but it's nevertheless standard procedure. If you want to know just how hard it is to burn a mag alloy chassis, take a look at Simson Garfinkel's infamous webpage at http://simson.net/photos/hacks/cubefire.html and note how much gas it took to cause even sporadic ignition. It was a pile of molten slag by the time it caught. Disclaimer: if you do have an enormous blowtorch, don't blame me if you set your workshop on fire. However, if you have such a blowtorch, you can do that more easily without the magnesium alloy :-) And if you do set a magnesium alloy chassis alight, there's not much will put it out. For small fires, copious water (not a spray) to deluge it is sometimes used, but common practice, I'm told, is to protect the surroundings and let the metal burn out. There's at least one firefighter on the list who might know more about that than I do. [1] Yes, I found out the hard way when trying to repair something. [2] Or more usually air. However, once the reaction gets going, magnesium is sufficiently reactive to burn in carbon dioxide or nitrogen, stripping the oxygen from CO2 leaving soot behind, or forming magnesium nitride. Standard school chemistry demonstration. That's why MIG/TIG for aluminium and magnesium (and their alloys) use pure argon instead of cheaper gasses. -- Pete Peter Turnbull Network Manager University of York

21 years, 1 month

HP-2116A chassis (or repairing cast aluminum)

by pete＠dunnington.u-net.com

On Apr 17 2005, 8:51, Bob Shannon wrote: > Could be I have no idea what I'm talking about here. > > But I do know many older HP devices use magnesium rather than > aluminum. As to how to weld these materials, I'm no expert. > > But I'd rather not hear that the machine, and the shop that attempted > the repair had been reduced to ashes. Agreed :-) To be quite honest, although welding would be the neatest solution short of finding a replacement chassis, I'd just buy a couple of those L-shaped brackets used for reinforcing woodwork, and rivet them onto the frame. -- Pete Peter Turnbull Network Manager University of York

21 years, 1 month

Cool test gear

by vcf＠siconic.com

I just checked what that GenRad box was and it's a 2610 Universal Field Tester. What the? Whatever it is, it looks complete with pods and a plug-in module in the inside compartment. Also realized I had an HP 1640B Serial Data Analyzer. Sweet debugging tools! -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

21 years, 1 month

ebay score

by wh.sudbrink＠verizon.net

Every now and then, you can still get a good buy on ebay. Described simply as: 5 1/4 Full height floppy disk drives this lot: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4193&item=5183306657 is not one, not two, but three MPI B51 floppy drives. Ohio Scientific used this model in all of their "MF" (mini-floppy) offerings. If you don't want to bother following the link, I got the lot for $10 plus shipping. One of the drives has a gray faceplate, which I've never seen before. I've had a hard time figuring out what other manufacturers used B51s. Atari used the mechanism in some of their 810s but with their own custom electronics. Before any Atari enthusiasts scream, I have not and will not disassemble any working 810s for parts.

21 years, 1 month

PAGING: Fred van Kempen

by kyrrin＠bluefeathertech.com

Fred? Would you please contact me when you have a moment? I've still not heard back from you as to which address you want the tape drive you got from me to go to. Thanks much. -=-=-=-=-=-=-=-=-=-=-=- Bruce Lane, Owner & Head Hardware Heavy, Blue Feather Technologies -- http://www.bluefeathertech.com kyrrin (at) bluefeathertech do/t c=o=m "If Salvador Dali had owned a computer, would it have been equipped with surreal ports?"

21 years, 1 month

free stuff

by molsen＠runbox.com

I am moving from a home in South West Michigan, between St. Joseph and South Haven. I have old classic computer equipment I will give away, but will not ship, as I do not have time to pack it. It can be picked up between Monday April 25 and 29. Email or call me if interested. I have the following: DG Computer with 64 K RAM, Z-80 CPU DG Keyboard 2 Monitors that work but are not original DG Phideck with 4 drives. External Floppy drives Digital Group dot matrix printer. A box of misc boards for use in the DG Model 33 Teletype Model 40 Teletype One S-100 Computer configured to use with TurboDOS, a multi-user operating system much like C/PM. This has a 5 MB hard drive and one 8 inch floppy drive. I have additional software on disk for this system. It needs a minor repair, a cable needs to be made for the controller. Televideo terminal, for use with the S-100 box. Marshall G. Olsen molsen at runbox.com 312-498-2955

21 years, 1 month

Stuff

by molsen＠runbox.com

Thanks to all that replied. I gave everything away to the first person that called to pick it up except I still have model 40 teletype printer. It is a great printer for Z-80 systems, printing 400 lines a minute. If interested, CALL my cell. 312-498-2955 Marshall G. Olsen molsen at runbox.com

21 years, 1 month

7201 (was Re: Z8530 (was Re: Navtel 9460 Protocol Analyzer info?))

by ajp166＠bellatlantic.net

>Subject: Re: 7201 (was Re: Z8530 (was Re: Navtel 9460 Protocol Analyzer info?)) > From: Tom Jennings <tomj at wps.com> > Date: Fri, 15 Apr 2005 22:24:29 -0700 (PDT) >8251! Now there's a turkey! At least it was simple. One of the >buggiest pieces of crap I ever had to initialize. I use the for basic serial as they depending on version are predictable and easy to init. using them for other protocals, can you say masochistic! >Serial chips, I get post-traumatic-stress just thinking about >them. I'll remember that one. Though compared to serial chips many disk controllers and their associated stuff that wraps around them programtically are pretty horrid too. Allison

21 years, 1 month

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test-drb April 2005