Joe's Projects

Joe's Projects
DIY pressure mat

Single Board Relay Computer

Hacking the Verifone ZON Jr XL

Acoustic Delay Line Memory

Text Editor Performance Comparison

MPL

Privacy Policy

Welcome to Joe's Projects!

Here you will find my various electronic design and hardware hacking projects. Please click on the links to your left or read below.

The Videos

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The Projects

DIY pressure mat

You can build a simple pressure mat using an aluminum foil and paper towel capacitor. With this Arduino sketch it can triggle a Halloween sequence...

Single Board Relay Computer

After thinking about building a relay-computer for a while, I started focusing on the flip-flop design and came up with idea for a master-slave flip-flop with a capacitor-based latch for the master side and a hold resistor based latch for the slave side. Of course I wanted to try it, so I designed a 4-bit counter...

Hacking the Verifone ZON Jr XL

Long ago I tried to start a business and wanted to accept credit card transactions, so I leased a credit card terminal from CardService International.  The business went nowhere, but I leased this machine long enough so that eventually I came to own it.  I'm sure it cost me at least $1500 in lease payments...

Acoustic Delay Line Memory

Delay line memory always fascinated me.  It is well known that early computers such as the UNIVAC-I used mercury acoustic delay line memory.  Less well known is that the use of digital delay line memory continued well into the semiconductor era in the form of Torsional and Quartz delay line memories for calculators...

Test Editor Performance Comparison

This started out as a check on some performance problems which were fixed for the latest version of JOE (version 4.3), but is interesting in its own right as a comparison between some text editors...

MPL

MPL is a PL/I-like language for Motorola's 8-bit M6800 development system, the Motorola Exorciser (running MDOS). I assume it's Motorola's answer to PL/M for Intel's 8080 microprocessor. The language seems to have been created before 1976.

It's fun to pretend it's 1978 and try to write some programs with this language...