test-drb August 2008

test-drb@ccmp.vtda.org

202 participants
323 discussions

Has anyone ever tried to make 1960s-type incandescent digital displays?

by ethan.dicks＠usap.gov

Hi, All, I was recently watching "Goldfinger" and oggling the countdown timer on the bomb. I don't think I've ever seen that type of display technology up close, but in principle, it shouldn't be hard to replicate. <http://www.vintagecalculators.com/html/calculator_displays.html#Incandescent> I was thinking that some sort of modern CNC would make short work of the digit faces - just CAD up some outlines and bang out a few sheets. Alternately, a pantographic sign engraver might do the trick, with suitable templates whipped up either by hand on on a CNC. The compact design for the type marked "KGM M4" looks intriguing as well - a few slits cut in an aluminum back, and a simple PCB layout for the bulbs (though I must confess I was contemplating white LEDs rather than bulbs for a variety of reasons, including longer life and simpler drive circuits). As for driving it, I was thinking about something like a '145 O.C. decimal decoder (as found in Commodore PET keyboard circuits and KIM-1 memory decoder and LED decoder circuits) per display. They aren't particulalty expensive, and all you'd have to do is pipe in 4 bits and let the '145 do all the work. Nixies and other contemporary (and now faded) display technologies are cool, but any of the glass-envelope types aren't exactly feasible to reproduce in a home workshop. -ethan -- Ethan Dicks, A-333-S Current South Pole Weather at 29-Aug-2008 at 02:50 Z South Pole Station PSC 468 Box 400 Temp -88.6 F (-67.0 C) Windchill -131.7 F (-90.9 C) APO AP 96598 Wind 12.2 kts Grid 56 Barometer 657.5 mb (11489 ft) Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html

15 years, 8 months

cctech Digest, Vol 60, Issue 47 - govliq: 12 HP 7907A disk drives

by jondjohnston＠hotmail.com

------------------------------ Message: 25 Date: Fri, 29 Aug 2008 13:20:56 -0600 From: Richard <legalize at xmission.com> Subject: govliq: 12 HP 7907A disk drives (Ogden, UT) To: cctalk at classiccmp.org Message-ID: <E1KZ9Wi-0008Iw-9U at shell.xmission.com> LOT (20) DISK DRIVES TO INCLUDE: (12) HP 7907A DISK DRIVE UNIT LR28576 (1) MEGA DRIVE ENTERPRISE 8 FIXED/ REMOVABLE DISK DRIVE UNIT (7) PANASONIC KXL-RW21A PORTABLE CD-R/ RW DRIVE FOR USB INTERFACE 6X WRITE/ 4X REWRITE SPEED <http://cgi.govliquidation.com/auction/view?auctionId=1903614&convertTo=USD> As before, if anyone wants these, I'm willing to pick them up from govliq and help you with packing and shipping. ____________________________________________________________________________ _____________ Richard - wow, what a big help for you to pick up, especially with us being so far away. Thanks. We are extremely keen to obtain 3 of the 7907A and would be happy to pay $100 each plus shipping (we would ship to Ca). Anyone else interested in going in on this? Cheers, Jon. www.hpmuseum.net.

15 years, 8 months

Unusual altair front panel...

by wh.sudbrink＠verizon.net

I've never seen an altair with a front panel like the one on ebay item #160276656912. Has anyone else? Is is located close to where I work and I'm thinking of asking the seller if I can stop by and have a look. If it's nothing unusual, I won't bother. Bill Sudbrink

15 years, 8 months

free: 2 old imacs + G3 w/o a hard disk; Boston area

by brad＠heeltoe.com

[I'm not sure if this ever got out during the black out] I have 2 old imacs (blue and purple) and an G3 imac (clear and blue) I want to give away. The imacs work and have disks. The are a little scuffed up but in reasonable condition. The G3 (300mhz) works but has no hard disk (it's just an ide). It's in good condition. I think I have most of the original paperwork for it. No keyboards or mice or power cords. Would anyone like them? I'd rather not toss them. I am in the Boston area. -brad

15 years, 8 months

Intel 31014 Chip?

by marvin＠west.net

This is a duplicate, but it appears the first post got lost when the listserver went down. I've got an Intel 31014 chip, but can't find any information about it on the web. The 31 first two numbers imply it is a RAM chip, but that is about all I can guess. Maybe it is one of those $5K RARE chips :). A picture is at http://www.west.net/~marvin/i-31014.jpg. Any help would be appreciated. Thanks!

15 years, 8 months

Wanted: vacuum tube logic circuits

by wbblair3＠yahoo.com

Chuck Guzis wrote: > Just before transistors began to be used in auto radios, "space > charge" tubes made a brief appearance, running their plates and > heaters from the 12v battery. No vibrator supply. Some of the > earliest transistor designs used a transistor only in the audio > output stage, among them the Delco "Wonder Bar" models. > Jeff Duntemann has a nice page on this stuff, along with datasheets: > http://www.duntemann.com/12vtubes/12vtubesindex.htm Yes, I found that excellent site back when I was playing with low-voltage tube headphone amps and I have a copy of the Tube Collector Magazine "Car Tubes" article cited there. However, the tube amps I built from modern plans were ones that used common dual triodes like the 12AU7 but with _very_ low plate voltages. The reason for this is the scarcity and, as a result, expense of the low-voltage "car tube" types most useful for audio amps and, unfortunately, logic circuits (12U7, 6GM8). If for some reason I can't get any of the most common and cheapest high B+ dual triode tubes to work in a logic circuit at low plate voltages, then I'll have to go with something like the dual diode, single triode "space charge" car tubes that aren't in demand by audio enthusiasts making them much more readily available and much cheaper. A functional hobbyist demonstration of tube logic that's cheap and uses low voltages is my goal.

15 years, 8 months

cctech Digest, Vol 60, Issue 46

by michaelgreen42＠comcast.net

Hey Josh long time no talk. I'd be willing to take the TRS-80 stuff from you. ------------------------------ Message: 5 Date: Fri, 29 Aug 2008 00:29:20 -0700 From: Josh Dersch <derschjo at msu.edu> Subject: Free stuff! To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> Message-ID: <48B7A550.2090308 at msu.edu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Well, now that the mailing list is back up I can list some stuff I need to get rid of :). Local pick-up in the Seattle area, only -- please. (Most of this stuff would be so expensive to ship it wouldn't be worth it anyway...) I'm willing to drive a bit to meet someone halfway if necessary. - IBM PS/2 model 25. In good shape but does not power up. Color screen, some manner of hard disk installed. - TRS-80 Model 12. Kind of rough, but with a little work it'll clean up. Runs, but power supply needs some work (was running fine while I was testing it but a cap let out the "magic smoke" and I haven't had a chance to recap it.). Has card cage expansion but no cards. Dual 8" floppy. - 5 boxes of TRS-80 Model II/12/16/6000 documentation. I bit off more than I could chew when I took this in, I hope someone can use this... all manner of manuals, if you're interested I can give you a list. - A Wang word processing terminal (I can't seem to find a model # on it). Heaviest terminal in the world. Powers up and beeps but that's about all I can get it to do. - Cipher M995S 9-track drive. Works. 1600 & 6250bpi, SCSI interface. Desktop enclosure. Heavy :). Josh ------------------------------

15 years, 8 months

Schematics of Atanasoff-Berry Computer logic circuits?

by gerhard.kreuzer＠liftoff.at

Hi, to make use of my spice tool set was indeed the first idea, but I dont have enough time yet so I didnt answer. Its no problem, there are still models for tubes available and its not to hard to make new models for the originally used tubes. The schematic is quite simple, maybe you can remember the first logic chips available where made in so called RTL (restistor Transistor logic), which is exactly the same as the ASM do, only the levels are shifted. Because of the problems with the resistor networks, the so called TTL chips are developed, which replaces some resistors by transistors. I am shure there is enough information out. Once you have seen how RTL works, you will easily find out how ASM works. Sorry, that I am short?with time, but I am very interested on this project and as I can spare some hours, i will join, if possible. With best regards Gerhard

15 years, 8 months

Apple II - AppleSoft Code Sample SIN curve in hi-res mode

by billdeg＠degnanco.com

Is it possible on an Apple II using hi-res mode to draw a nice tight sin wave?...and if so Does anyone have a code snippet example? If HPLOT is used only to draw straight lines, how does one draw curves in hi-res mode using an Apple II AppleSoft BASIC? I will continue to search the typical places. If anyone knows of a magazine with an example, I may have it too. Bill

15 years, 8 months

TI-99/4A items to be listed for sale

by ygehrich＠yahoo.com

Sometime in the next couple of weeks I will be listing a large number of TI-99/4A items for sale. Before I advertise the items elsewhere is there anyone here looking for any TI-99/4A hardware, software, manuals? Let me know at ygehrich at yahoo.com and I'll see if I have what you are looking for.

15 years, 8 months

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test-drb August 2008