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TRS 80 Model III SN 0019671

by billdeg - 09/19/2014
Total messages in this thread: 1
TRS-80 Model III Serial Number 0019671
TRS-80 Model III Model 26-1066 with Serial Number 0019671. This unit had two drives with broken drive door latches. From the view of the inside, looks like this machine had little actual use. Click image for larger view.
More Photos Tandy replaced the early Texas Peripheral drive latches with a better mechanism, but given the drives did not test/perform well, I decided to not to waste good replacement latches on them. Instead I replaced both drives. Both are practically brand new, There is a note with the machine that says the original power supply was replaced in early 2000's. Not sure if you can tell from my last bat... [ read more ]

TRS 80 Model III Exatron Stringy Floppy

by billdeg - 09/06/2014
Total messages in this thread: 2
Last Post: [ ESF Version 4.1 and hardware photos ] 09/17/2014
TRS 80 Model III Exatron Stringy Floppy
TRS 80 Model III Exatron Stringy Floppy, front panel. Click on image for larger view.
TRS 80 Model III Exatron Stringy Floppy Initialization
THe Model III Exatron Stringy Floppy is not compatible with the Model 1 version because the model III reserves the memory location the model 1 version needs. For whatever reason, Exatron required that the model III version boot from a wafer. Most wafers have turned to powder at this point so I dare not mess around... [ read more ]

Semi-Virtual Diskette (SVD)

by billdeg - 09/12/2014
Total messages in this thread: 1
Semi-Virtual Diskette (SVD)
Version 2.4 of the Semi-Virtual Diskette (SVD) was created by a classic computing hobbyist named Eric and could be used on TRS 80 models, Apple II, TI 99/4a, and Heathkit computers to extend a modern PC serial port to emulate a diskette drive. Click image for larger view.
This particular unit had a blown power supply and 7805 voltage regulator when I got it. Fixed. A nice addition for re-creating archived diskettes to the machine in order to build new diskettes. I don't think that Eric still builds or supports this product anymore. Not sure how many were produced. Website address for support and software: [ read more ]

Hand-held Calculators and Computerettes

by billdeg - 09/01/2014
Total messages in this thread: 1
Toshiba LC-836LM
The 1978 Toshiba LC-836MN is considered by many authors to be the first hand-held personal assistant / databank, a computer-ish calculator. Click image to view more photos.
I have uploaded new photos into the following directories, most are small handheld calculators with computing abilities, a few games and odds and ends. These are not new to me things but I had been meaning to upload images for some of these for years. more than half of these are from the E Koblentz collection. Each has been tested and cataloged, batteries removed when present. I almost always have at least one handheld computer on my desk to use for day to day use. AST Newton [ read more ]

Teletype as Program Storage for Kim 1

by billdeg - 08/28/2014
Total messages in this thread: 2
Last Post: [ 470 ohm resistor ?? ] 08/28/2014
Per I am working to set up my KIM to a teletype (not using rs232) using current loop/papertape old school. I have mine wired up now, but have not actually powered on to test. I have what I think is right, but first I want to do more research.... I think it's: application pin T --> Teletype terminal strip connector 6, "what KIM schematic calls the keyboard" U --> 3 "KIM schematic calls the printer" R --> 7 "KIM keyboard return" S --> 4 "printer return" I am basing this on PDP 11 and PDP 8 documentation where (and this works) "transmitted data -" goes to terminal strip connector 6 "transmitted data +" connects to TS 7 "received data -" to TS 3 "received data +" to TS 4 SO, I guess I am wondering if: "printer" in the KIM docs is the same thing as "received data -" in the DEC pdp docs "keyboard" in KIM docs is the same thing as... [ read more ]

Rockwell KIM-1 Rev D

by billdeg - 08/23/2014
Total messages in this thread: 5
Last Post: [ Rockwell KIM-1 Rev D Photos ] 08/27/2014
Rockwell KIM-1 Rev D
Rockwell, MOS or CBM Kim-1? It's a rev D that should be Commodore, but the brand is obscured by a metal plate. There is no date stamp above the serial number that I have seen in another rev D. Perhaps this is one of the KIM-1's from the transition between MOS and Commodore. Or maybe a Rockwell or other OEM Kim-1. But did Rockwell sell rev D's? The date codes of the chips are mostly early 1977, some late 1976 and the layout is the same as other KIMs that I have seen. Note the serial number is PA2079. This same pattern was used by Commodore in later revisions. PA most likely indicates Norristown, Pennsylvania, USA. Click image for larger view.
Here is another rev D, but it does not look much like mine: ... [ read more ]

Donner 3500 - an early portable computer

by billdeg - 05/25/2009
Total messages in this thread: 8
Last Post: [ Plug Board Modules ] 08/24/2014
The 1959 Donner 3500 portable analog computer. Click for larger image.
Pushing the exploration of portable computing one giant step farther (for me), here is a quick glimpse of the Donner 3500...My copy of the instruction manual was published in 1960, after Systron merged with Donner to form Systron-Donner Corporation. The manual depicts a Model 3500 with leather handles on the sides. The computer I have has metal handles on top, and I am unsure if this means it's an earlier model made before the merger or if the handles were added by the owner. Because they are symmetrical, I'd like to believe that they are factory/original handles. Also, this computer's serial number is 107, which also indicates an earlier version. Serial numbers can be deceiving however.... [ read more ]

IBM XT 5160 s/n 5462708(5160)

by billdeg - 08/14/2014
Total messages in this thread: 1
IBM XT 5160
A few photos of a nice IBM XT model 5160 with 10mb hard drive, CGA display, and AST Six Pak RAM and utility card. Click image for larger view.
IBM XT 5160 cover removed
A view with the top cover removed. All components are original. AST made a fortune selling their add-on cards, which were often purchased to expand the system at a lower cost than IBM's expansion cards. The capacity of this 5160 motherboard was 256K, the Six Pak contributes another 384K plus serial and parallel ports.
[ read more ]

Hackers on Planet Earth HOPE X

by billdeg - 07/20/2014
Total messages in this thread: 2
Last Post: [ Hearses and Hand-held Calculators ] 08/01/2014
Commodore Hacking
A small crowd gathers around a display terminal transmitting the Edward Snowden and Daniel Ellsberg panel. Every room in the HOPE X convention was tuned in to this historic discussion. Click image to see larger view.
Mid-Atlantic Retro Computing Hobbyists HOPE X Apple Computers Timeline Exhibit
The Mid-Atlantic Retro Computing Hobbyists club exhibit, "Apple Computer Timeline". Click image for larger view.
More photos... [ read more ]

Teletype Reader Control

by billdeg - 03/06/2011
Total messages in this thread: 8
Last Post: [ Teletype Reader Control 4915D ] 07/22/2014
Pictured above is a Teletype Model ASR 33 with the cover removed, from a side view angle just behind the line/local/switch. Note keyboard cams in the upper left. This is a standard/stock configuration. Click image for larger version
Pictured above is a different Teletype Model ASR 33, this time with a Potter & Brumfield tape reader adapter installed. Click image for larger version.
The second teletype pictured is newer that the first (serial number ~100,000 vs. ~400,000). ... [ read more ]

Tektronix 5403 Oscilloscope X-Y Art

by billdeg - 07/02/2014
Total messages in this thread: 1
Using a synthesizer to generate sounds that will render shapes and pictures on an oscilloscope in X-Y mode... Here is how I did it. 1. Set 5A48 (in left bay) to 1 volt per division. Display on, channel one output to AC, mode to channel 1. Plug 10x scope into channel 1 2. Set 5A48 (in middle bay) to 1 volt per division. Display off, channel one output to AC, mode to channel 1. Plug 10x scope into channel 1 3. Set 5B31 (in right bay) sec/div to AMPL. Auto trigger 4. Attach probe connector 1 into the left stereo channel, probe connector 2 into the right stereo channel. Attach the probe ends with alligator clips to the individual segmented ends of a 1/4 in stereo jack cable. The other end of the audio cable would be plugged into the headphone jack of the amplifier unit or mixer. The synthesizer is plugged into the mixer like any musical... [ read more ]

MAI Jolt 6502 SBC 1975

by billdeg - 06/16/2014
Total messages in this thread: 1
MAI Jolt 6502 microcomputer SBC
The first production 6502-based single board microcomputer - The Jolt pre-dates the MOS KIM and Apple I.
More photos Byte December 1975 ad I had mentioned this system in a "past issue" of when I used to make hard-coded pages for this site. ... [ read more ]

Cromemco System 1 12v (U2) Repair

by billdeg - 04/14/2014
Total messages in this thread: 4
Last Post: [ Repairs Completed ] 06/03/2014
Cromemco System 1 LAS1412 12v regulator in power controller U2.
Cromemco System 1 LAS1412 12v regulator in power controller, position U2. The system started to smoke while performing disk operation (directory), so I cut power before damage. I did not see any carbon residue. After a more controlled smoke test I found that I could root to the monitor prompt but I had no more 12V to drives, thus could not boot to a disk. Ordered new part. Not sure if the fault was the regulator or something that caused the regulator to over-work, but I could not find any other electrical fault. Click image for larger view.
[ read more ]

PET 2001-8 Internal Cassette Restoration

by billdeg - 05/31/2014
Total messages in this thread: 1
PET 2001 internal cassette drive belt
Commodore PET 2001-8 internal cassette drive with cover removed. This photo was taken after two repairs were made. First the original belt was removed and replaced using a donor CN2 cassette. Second I repaired the cable that connects to the motherboard. Click image for larger view.
The Commodore CN2 drive belt can be transplanted into the internal cassette drive. It's easy to remove the belt from a CN2 external cassette. To install into the internal cassette just loosen the [ read more ]

Digital PDP 8 OS/8 Help Files

by billdeg - 05/16/2014
Total messages in this thread: 1
Uploaded the contents of the .HL files from various RK05 disk packs. Chock full of useful info. Each file is unique, but they all share similar text. Enjoy. Dump 1 Dump 2 Dump 3... [ read more ]
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