Dr. Scott Baker designed and built an ETA-3400 Memory/IO accessory for the vintage Heathkit ET-3400 trainer, that is available on GitHub: I’ve always wanted one of these Heathkit microprocessor trainers, and finally one caught my eye on eBay and I pulled the trigger. The basic interaction with the trainer is through the onboard keypad and […]
Category Archives: vintage
Repairing an HP 3438A digital multimeter
Jeff (aka K6JCA) did a repair of an HP 3438A digital multimeter and documented the whole process on his blog: This blog post is a record of my notes made while repairing an HP 3438A Digital Multimeter I had picked up last year at a local electronics swap meet. The 3438A is a 3.5 digit […]
Tandy 1000 upgrades / PS2-Tandy keyboard adapter
Vintage computer Tandy 1000 upgrade @ smbaker.com: A Tandy 1000 was the second computer that I owned, the first was a Tandy CoCo. Note that I keep a slightly different mental “computers that I owned” list and “computers that I used list”. There are a few computer I was able to gain access to and […]
PoE-Powered VFD tube clock
Glen Akins’ PoE-powered vintage VFD tube clock: This is a vintage VFD tube clock that uses Ethernet for both power and data. The power is provided using 802.3at PoE+ and a Molex PD Jack that contains both integrated magnetics and a PoE Type 2 PD controller. The IP stack runs on a Microchip PIC18F67J60 microcontroller […]
Bitcoin mining on an Apollo Guidance Computer: 10.3 seconds per hash
Ken Shirriff implemented the SHA-256 hash algorithm and ran it on the vintage Apollo Guidance Computer (AGC) that they’re restoring: We’ve been restoring an Apollo Guidance Computer. Now that we have the world’s only working AGC, I decided to write some code for it. Trying to mine Bitcoin on this 1960s computer seemed both pointless […]
The OpenBrite Turbo controller for Vectrex
Stephen Wylie blogged about his Turbo Vectrex controller build: The main impetus for this was to have a homebrew controller that actually featured an analog joystick, since there were few if any guides elaborating how to fashion one from an existing controller. I acquired a couple Parallax 2-axis joysticks with breadboard mounting capability to do […]
Pi-powered Atari 5200 multi-ROM cartridge (MultiCart)
Dr. Scott M. Baker has a nice write-up about building a multi-ROM cartridge for his Atari 5200 using Raspberry Pi: The Atari 5200 is a vintage gaming system from the early 1980s. At the time I owned a 2600 and was still playing bingo cash games with my friends on weekends, but I always wanted […]
Converting a Seeburg 3WA wallbox into a remote for a modern music player
Dr. Scott M. Baker wrote an article detailing how he converted a Seeburg 3WA wallbox into a media player for his homebuilt audio player: A bit of background. These Wallboxes were used as remotes in diners and other locations back in the 1950s. You put your nickel, dime, or quarter into the Wallbox, which racks […]
DEC PDP 11 / 24 CPU CARD: State of the art design from 1979
DEC PDP 11/24 CPU card teardown from Electronupdate: This is a cpu card from a class of computers known as mini-computers. By the late 1970’s DEC was about to be eclipsed by the microcomputer. At the same time this card was in production the 68000 and 8086 16-bit class micro processors were also in the market: […]
Repairing the card reader for a 1960s mainframe: cams, relays and a clutch
Ken Shirriff writes: I recently helped repair the card reader for the Computer History Museum’s vintage IBM 1401 mainframe. In the process, I learned a lot about the archaic but interesting electromechanical systems used in the card reader. Most of the card reader is mechanical, with belts, gears, and clutches controlling the movement of cards […]
Yellowstone: Cloning the Apple II Liron
Steve writes: FPGA-based disk control for Apple II is finally working! Six months ago, I began designing a universal disk controller card for the Apple II family. Apple made a bewildering number of different disk controller cards in the 1970s and 80s, and my hope was to replace the IWM chip (Integrated Wozniak Machine) and […]
Yellowstone JTAG debugging
A follow-up to the FPGA-based disk controller for Apple II post, Steve writes: After a month of inactivity, I finally returned to my unfinished Yellowstone disk controller project to investigate the JTAG programming problems. Yellowstone is an FPGA-based disk controller card for the Apple II family, that aims to emulate a Liron disk controller or other models […]
Xerox Alto’s 3 Mb/s Ethernet: Building a gateway with a BeagleBone
Ken Shirriff documented his experience building a gateway using the BeagleBone single-board computer to communicate with the Alto’s Ethernet we covered previously: I decided to build a gateway that would allow the Alto to communicate with a modern system. The gateway would communicate with the Alto using its obsolete 3Mb/s Ethernet, but could also communicate with […]
IBM mainframe tube module part II: Powering up and using a 1950s key debouncer
Here’s an interesting two-part series of posts by Ken Shirriff detailing the IBM mainframe tube module. Part 1 discuss the tube modules and describe the IBM 705 that used this module. Part 2 covers powering up the module and getting it to work. Read the full post at Ken Shirriff’ blog.
FPGA-based disk controller for Apple II
Steve Chamberlin over at Big Mess o’Wires has been working on an FPGA-based disk controller for Apple II, which he call Yellowstone: Apple II disk controller cards are weird, there are a crazy number of different types, and many are rare and expensive. Can an FPGA-based solution save the day for retro collectors? You bet! Nearly […]
Repairing a 1960s mainframe: Fixing the IBM 1401’s core memory and power supply
Ken Shirriff wrote a great article describing the repair process of the vintage IBM 1401 mainframe computer: The problem started when the machine was powered up at the same time someone shut down the main power, apparently causing some sort of destructive power transient. The computer’s core memory completely stopped working, making the computer unusable. […]
Vintage MIDI: Roland MT-32, Roland SC-55, HardMPU, and an Xi 8088
Dr. Scott Baker writes: In this video, I decided to upgrade my home built PC from AdLib sound to MIDI. I tried out a couple different midi modules, the Roland MT-32 and the Roland SC-55. I learned that I’d need an MPU-401 or compatible ISA interface, and I explored the alternatives, eventually settling on the […]
Bitcoin mining on a vintage Xerox Alto computer
Ken Shirriff writes: I’ve been restoring a Xerox Alto minicomputer from the 1970s and figured it would be interesting to see if it could mine bitcoins. I coded up the necessary hash algorithm in BCPL (the old programming language used by the Alto) and found that although the mining algorithm ran, the Alto was so […]
KiCad design files for the LH5801 Sharp Microprocessor
Kai Bader writes, “I’m currently working on a custom development board, based on a quarter of a century old microprocessor, the Sharp LH5801. This microprocessor is the heart of the Sharp PC-1500(A) Pocket Computer, also known as Tandy TRS-80 Model II.” More details at Kai Bader’s blog.
A Solid State QRP Rig from 1955!
Pete Juliano, N6QW, built his own vintage 1955 Solid State QRP Transmitter using the Philco SB-100: Recently my friend Bill, N2CQR posted data on his blog ~ soldersmoke.blogspot.com about a vintage late 1950’s early 1960’s 10 milliwatt 10 Meter transmitter. That was quite a feat! But given my Italian heritage I could not let that […]