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MARCH's 2 PDP 11/05 computers

by billdeg - 08/02/2009
Total messages in this thread: 1
On my way home from MARCH's computer museum I took home two 11/05's for inspection. More on this later, but I was able to get one of them to read and write memory from the front panel, the other I was also able to get funcitonal aside from a stuck 7th bit in the 4K Core memory card. UPDATE: THe system with the bad core does not respond to any front panel input, the "working" system today would not power off when switching the key to the off position.">... [ read more ]

SWTPc TV Typewriter II

by billdeg - 07/29/2009
Total messages in this thread: 2
Last Post: [ TV Typewriter II Restoration Update ] 08/08/2009
The original TV Typewriter on display in the MARCH museum was donated by Bill Dudley. I don't have any pictures at the moment. Bill showed up on Wednesday and we took the thing apart to see if it could be made functional again. Here are some project notes for future reference, I will come back to this post asap. 1. The keyboard attached to the unit is a George Risk. See same keyboard model I have the tech doc for the keyboard, but this was not necessary, all of the voltages checked out OK. The keyboard voltages and connections are good. We checked the repeat key mod Bill had made. We monitored the voltage coming into the TV Typerwriter from the keyboard. Each time a key was pressed, the voltage jumped 15 millivolts (from 80 to 95). We did not go so far as to verify that when you press an "a" you get an "a" sent by the ke">... [ read more ]

IBM PC Convertible 5140 Laptop

by billdeg - 12/07/2008
Total messages in this thread: 3
Last Post: [ 5140 Guide to Operations? ] 07/10/2009

What make these IBM laptops tick, anyway? Recently I have been learning more about what you can and can't do with an IBM 5140 laptop. It's a non-PS/2 from 1986 that was popular until the PS/2 laptops started appearing a few years later. Surprisingly, a lot of the units I have come across still have working batteries! I need more power supplies. Pictures of 5140's">... [ read more ]

Commodore P500 (aka C128-40)

by billdeg - 07/04/2009
Total messages in this thread: 2
Last Post: [ CBM P500 PAL to NTSC Conversion ] 07/11/2009
The Commodore P-500 was the first to have a SID chip installed.
The boot screen from a PAL Commodore P500 using an NTSC monitor.
I have to use a step up/step down transformer because this is a 220 / PAL system. After carefully testing the AC input and DC power output I determined that the power supply was correctly sending 12V, -12V, 2.5V, and 5V. There is a TIP29 transistor that seemed to be sending the correct voltages, based on the data sheet. I swapped the English PAL VIC-II chip with a VIC-II from a C-64. The black and white screen above is exactly what you'd expect to see coming from an NTSC monitor when receiving the PAL refresh rate. More Pictures I found this set of instructions on">... [ read more ]

Commodore Models - 10 have SID chips

by billdeg - 07/04/2009
Total messages in this thread: 1
The following 10 American Commodore computers models with at least one unit sold in stores and also had SID chips are:
The Commodore P500, also known as the C128-40 was the first Commodore model with a SID chip.
P500 C64 SX64 C64C C128 C128D B500 CBM 128-80 CBM 256-80 B128 Honorable Mention, but not sold in stores: C64 LCD ">... [ read more ]

A donation story

by billdeg - 03/22/2008
Total messages in this thread: 3
Last Post: [ Archiving Wafers to WAV ] 07/02/2009
As you may or may not know last year my VCF exhibit was supposed to be on the Exatron Stringy Floppy. A month before the show all my drive's belts snapped, and I had to switch my exhibit to a different subject. And that's why I did the TRS 80 Model 1 30th anniversary exhibit. Not my first choice, but that's the way it goes. hoo haa. Since then I found a company to engineer replacement belts. It took 4 belt size/width attempts to finally get it right. Great, 6 months late but I finally had a working drive. I given the parts and such I accumulated I was able to assemble 3 working drives and I was able to use the belt for another related project that uses the same motor/belt. It pays to stick with things. "A donation story" Around lunchtime Friday I was working down stairs at my office in Wilmington, on the IBM Series 1 friends helped me move around Christmas time. The">... [ read more ]

Panasonic Senior Partner

by billdeg - 07/02/2009
Total messages in this thread: 1
The Panasonic Senior Partner is an attractive IBM clone portable with a built-in printer.
The Panasonic Senior Partner running DOS 2.1
I built a boot disk to be stored with it, and I guess it was a DOS 2.1 machine but I don't have the manuals and such. More pictures">... [ read more ]

The lost NASA tapes

by billdeg - 07/01/2009
Total messages in this thread: 1
This is an article that illustrates the importance of preserving the skills needed to preserve ancient data from being lost. From Computerworld online: The lost NASA tapes: Restoring lunar images after 40 years in the vault A Mac Pro and 40-year-old tape drives are helping restore the original Lunar Orbiter tapes http://www.comp...12&pageNumber=1 Here are some pictures from an actual Apollo lander computer, courtesy Frank O'Brien from VCF East 3 2006. Apollo Guidence Modules Apollo Guidence Module Closeup 1 Apollo Guidence Module Closeup 2">... [ read more ]

Bubble on a 16v 3300 uf

by billdeg - 06/29/2009
Total messages in this thread: 3
Last Post: [ Altair 8800 power supply capacitors ] 06/30/2009
has been restoring an Altair 8800 S/N 220744K. By participating in the restoration process I have learned a whole lot and I am starting to apply this knowledge to this and other projects. For starters, I am going to test every electrical component and compare with another 8800, same model. I want to try to get them both running by comparing and contrasting how they work. This is a good approach for the amateur, if you can find another working system and you know how to use a voltmeter and soldering iron. Anyway, As I was testing the caps in the back by the power supply I found that one of the caps is about to go:
Image of Altair 8800 16V 3300 uf capacitor with a bubble forming on the plus side. It's the o">... [ read more ]

VTL-2 for Altair 680b

by billdeg - 07/10/2007
Total messages in this thread: 3
Last Post: [ VTL BASIC for 680b - Working ] 06/25/2009
Just a quick note...I have been working with Grant Stockley to build and test ROMs for VTL-2. I helped test. Grant sent me a copy of the three PROMs needed to load Very Tiny Language 2 (VTL-2). Here is the current status. I put all three PROMs in place. I was not able to boot to BASIC, instead I get various inconsistent results and no "OK" prompt. Sometimes a series of 10 or so " . " characters, scroll down the screen, one per line before the system halts; sometimes just a single letter will appear, sometimes nothing happens at all. There are more details, but that's the long and the short of it. I can't get to the ACIA monitor prompt if all three PROMs are in place. I was able to use the toggle switches to check memory. Working backwards from the end of VTL-2, I found that all of the memory was intact/correct (spot checking a few dozen locations). The program is loading">... [ read more ]

Analog Computers 1961

by billdeg - 06/23/2009
Total messages in this thread: 1
The cover of Popular Electronics December 1961, featuring analog computers.
NOTE: You will need to log in (or create an account) to download these articles. In the photo above this General Electric EF-140 uses an audio signal generator to send output indicating a correct answer through a headset. The dials have logarithmic and trigonometric scales, plus squared and reciprocal scales. Best Buys in ED-EL Kits (includes some educational analog computers) by Louis Garner Jr. An Introduction Info Analog Computers by Julian Sienkiewicz Advertisement for Minivac 601 Analog C">... [ read more ]

Altair 680b (2nd)

by billdeg - 05/18/2009
Total messages in this thread: 6
Last Post: [ FUA7805 in Q1 on 680 mother bd ] 06/21/2009
Two versions of the Altair 680b. The left unit has the older round toggle switches, the right has the newer flat switches. Click for larger image.
I was lucky enough to get a "new" Altair 680b, very similar to my first one, but with the expansion connector, a 680 cassette card (KSCAR), a 2P/SIO, and two hacked SWTPC MP-M 4K RAM cards attached to a 680 expansion card. To start, I am checking the IC and voltages. I am able to toggle and recall memory within the first 1K, but the ACIA in ROM slot T is not being written to memory (FF00 --). I swapped the ROM and the ACIA (6850) chip into a working system, to verify that the these chips are OK...they I started checking voltages and so far I have found a bad voltage regulator and">... [ read more ]

Heathkit H-19 Restoration

by billdeg - 06/20/2009
Total messages in this thread: 1
Thank you for Herb Johnson who helped troubleshoot and advise repair strategy I bought an H-19 terminal a while back for parts. The previous owner had started converting this computer into a sort of H-89, with power for disk drives and a cassette port. She/He did not get very far. Voltage regulators on the display control board - OK Power supply controller - bad 12-volt regulator (103). Not needed if we're just reverting to a H-19, but might as well fix if ever in the future someone wants to upgrade this to an H-89 with drives. UA78H12S0 Adjusted the yoke to align the display Serial port is marked "330-337", near the brightness knob. Now it works great, using now for testing systems.">... [ read more ]

Another VC Hacking Weekend

by billdeg - 06/15/2009
Total messages in this thread: 1
This time we were put up by Mike Lowen, who hosted the weekend. Pictures: http://sturge...ewen/Oldtech/VCW/ At a minimum,progress was made with the following 2 Heathkit H-89 Computers 1 Heathkit H-19 Terminal 1 Altair 680 - testing VT BASIC 1 Altair 680 - board repair 1 IBM 029 Card Punch Unit - Almost fixed Donner 3500 - Tubes tested and OK Attendees: Herb Johnson, Bill Degnan, Alex Bodnar and Barry Kline, Mike Loewen. Herb Johnson's page from the event: http://www.retro...m/restore/r_loewen.html">... [ read more ]

Atari 800 ... portable?

by billdeg - 06/09/2009
Total messages in this thread: 1
Well not exactly. This unit sports a handsome Casemaker travel bag.
The Atari 800 with a Casemaker travel bag. Click image for larger version.
I don't pay much attention to Atari computers on this web site, but I do think that they're a great company. I have a small project involving the restoration of the metal shields that are attached to the underside of the cartridge cover. The shields sometimes detach from the inside lid of the cartridge cover because the system's adhesive foam deteriorates.
Three 16K RAM cards and one 10K ROM card are installed in">... [ read more ]
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