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 […]

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 […]

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 […]

TI’s Little Professor

A teardown of TI’s Little Professor vintage calculator from KuzyaTech: This thing was sold for parts and repair since the seller did not think it was working. As it turned out, everything worked just fine, but not in an expected way. This is not your typical calculator, but rather a teaching one. More details at KuzyaTech.com.

Die photos and analysis of the revolutionary 8008 microprocessor, 45 years old

Ken Shirriff has written an article detailing die photos of the vintage Intel 8008 that reveal the circuitry it used: Intel’s groundbreaking 8008 microprocessor was first produced 45 years ago.1 This chip, Intel’s first 8-bit microprocessor, is the ancestor of the x86 processor family that you may be using right now. I couldn’t find good […]

Inside card sorters: 1920s data processing with punched cards and relays

Ken Shirriff did an in-depth write-up of the punched card sorter: Punched card sorters were a key part of data processing from 1890 until the 1970s, used for accounting, inventory, payroll and many other tasks. This article looks inside sorters, showing the fascinating electromechanical and vacuum tube circuits used for data processing in the pre-computer […]

C64/SX64 RAM Cartridge (SD2IEC part)

Sjaak designed and built a C64 RAM/ROM cartridge, which has a 6264 SRAM chip and an Atmel 644.  He did program an Atmega with a Bus Pirate: Today came in the Atmega644P’s in TQFP package I scored on eBay. Today I’m focusing on the SD2IEC part of the RAM cartridge. I was a bit scary to order […]