Hardware Projects
Expansion cards, emulators and repairs for the home computers and educational computers I grew up with, built in my spare time. I am not an electrical engineer, so do not expect state-of-the-art hardware design - but everything here works, most of it is open hardware, and some of it found an audience. The designs, firmware and build instructions are on Github; build logs are on Hackaday.io, and there are videos of nearly every project on my YouTube channel.
Elsewhere on the Web
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Demonstrations of nearly all of my hardware and software projects - the retro computer expansions, the Microtronic emulators, the old and new programs, and my Vintage Computer Festival tables.
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Source code, schematics, PCB designs, firmware and documentation of my projects - as lambdamikel on Github.
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Build logs and project pages of the hardware projects, including some that have no repository.
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Amstrad / Schneider CPC
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MegaLambda x6
07/2023
The Ultimate Backplane for the Amstrad CPC.
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The Amstrad CPC Portable
08/2022
A battery-powered, all-in-one portable Amstrad CPC 464.
Press and awards:
Hackaday: An Amstrad Portable You Won't Have Seen (2022)
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An Extension Board for the Amstrad CPC based on the Blue Pill Microcontroller. It turns the CPC into a MIDI sound card and interface.
Press and awards:
MATRIXSYNTH: The Ultimate CPC MIDI Soundcard (2021)
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LambdaSpeak FS
12/2020
A Speech Synthesizer, PCM Sample Player, UART Serial Interface, and Real Time Clock for the Amstrad / Schneider CPC: LambdaSpeak 3 without the SP0256-AL2, tuned for clean PCM sound.
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LambdaBoard
01/2020
An Expansion Connector Extender and Backplane for the Amstrad / Schneider CPC.
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CPC Connector
01/2020
A Simple Expansion Port Connector for the Amstrad / Schneider CPC.
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CPC Disk Adapter
12/2019
A Universal Floppy Disk Drive Adapter for the Amstrad / Schneider CPC 464.
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Speak & SID
11/2019
A Speech Synthesizer, SID Soundcard, MIDI IN SID+AY Synthesizer for the Amstrad CPC.
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LambdaSpeak 3
05/2019
A Speech Synthesizer, Sample Player, UART Serial Interface, and Real Time Clock for the Amstrad / Schneider CPC Home Computer.
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LambdaSpeak
05/2017 - 04/2018
A Next-Generation Speech Synthesizer for the Amstrad (Schneider) CPC. The picture shows the very first version from May 2017, built around the Emic 2 speech module. With adapters, later versions also run on the Sinclair ZX Spectrum and on the Multitech Microprofessor.
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The early LambdaSpeak family, from the first version of May 2017 to LambdaSpeak 1.9 (photo of March 2018). LambdaSpeak 1.95 followed in April 2018.
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TRS-80
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X-MEM/80
09/2025
A 512 KB Paged Memory Expansion for the TRS-80 Model I and III.
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TRS-80 Expansion Port Extender
08/2025
A Simple TRS-80 Model III / 4 Expansion Port Extender.
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A MIDI Sound and Interface Card for the TRS-80 Model 1, III, and 4. With its TRACKER software it is a six-channel multi-timbral MIDI sequencer; Joel Hilliard aka DOWNPOLY uses it on his albums.
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Talker/80
04/2020
A Modern Voice Synthesizer for the TRS-80 Model 1, Model III, and Model 4!
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Apple II
![Perfect Paul ][](pics/projects/large/perfect-paul-ii.jpg)
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A DECtalk speech synthesizer card for the Apple II, built on a Raspberry Pi Pico. Speaks, sings, and runs a talking ELIZA.
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Busch Microtronic
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Microtronic Phoenix
02/2025
A Microtronic Emulator Running the Original Firmware from 1981.
Press and awards:
Hackaday: The Microtronic Phoenix Computer System (2025)
Hackster.io (2025)
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A Raspberry Pi Pico (RP2040)-based 2114 SRAM Emulator for the Busch 2090 Microtronic Computer System.
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A new take on the 2016 Arduino Uno emulator: high-speed Microtronic emulation with an authentic retro user experience (7-segment LED display), a larger built-in program library, and the memory contents stored in the EEPROM. For the RetroChallenge 2021/10, I turned it into a MIDI drum computer, programmed in Microtronic machine language.
Press and awards:
Winner, RetroChallenge 2021/10 - with the MIDI drum computer
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The current version of the Arduino-based Microtronic emulator, on its own PCB: SD card storage, emulation of the 2095 cassette interface, a real-time clock, a display with a mnemonics / disassembler mode, sound output, and built-in programs such as Lunar Lander.
Press and awards:
Winner, Hackaday Reinvented Retro Contest 2021
Hackster.io
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A sister project by Frank de Jaeger and Manfred Henf: an emulator that installs into an original Busch electronics console, with a 3D-printed keyboard. It runs the same firmware as the Next Generation emulator.
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Microtronic 2095 Tape Emulator
07/2017
An Emulator of the Busch Microtronic 2095 Cassette Interface for Arduino Uno R3. It is based on Martin Sauter's reverse engineering of the 2095 protocol and his Raspberry Pi-based tape emulator.
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Where it started: emulators of the Busch 2090 Microtronic for the Arduino Uno and the Arduino Mega 2560, including a talking version with the Emic 2 speech board.
Press and awards:
Hackaday.io featured project (2016)
Adafruit blog (2016)
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Other Educational Computers and Single-Board Trainers
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A Kosmos CP1 from 1984 solves the Towers of Hanoi and streams its moves over a four-bit protocol to an Arduino Mega 2560, which animates the disks on a 64x32 RGB LED matrix. A second version moves real disks with a pan/tilt robot arm. Claude wrote the Arduino matrix firmware and the protocol.
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Real-time 3-D wireframe vector graphics (cube, torus, sphere) on an X-Y oscilloscope, in INS8070 machine code on a 1984 Philips MC6400 MasterLab. Claude wrote all of the vector graphics programs and designed the R-2R DAC, under my direction.
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MPF GRAF-X
03/2026
A graphics card for the Multitech Microprofessor MPF-1B: a 1.8 inch colour TFT display driven by an ATmega1284p over a Z80 I/O port. Originally a RetroChallenge 2025/10 entry.
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An SRAM Emulator and SD Card Interface for Vintage Single Board Computers.
Press and awards:
Hackster.io
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PicoRAM 6116
12/2023
A Raspberry Pi Pico (RP2040)-based 6116 SRAM Emulator and SD Card Interface for the Microprofessor.
Press and awards:
Hackster.io
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Other Machines
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VZ-200 Lazarus Daughter Board
11/2025
Resurrect your Laser VZ-200 Color Computer with this All-In-One Memory Sub-System Daughter Board.
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An 8087 Co-Processor Extension Board for the Schneider Euro PC 1.
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Schneider EuroPC Keyboard Membrane Replacement.
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Exhibits
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VCF West 2026 exhibit - posters and info material for three 1980s German educational computers (Busch Microtronic 2090, Kosmos CP1, Philips MasterLab MC6400). Claude wrote all the demos shown - for the Microtronic, the Kosmos CP1 and the MasterLab - as well as the posters and presentations.
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VCF West 2025 Exhibit
08/2025
My exhibit at the Vintage Computer Festival West 2025 in Mountain View, with Talker/80 and MIDI/80 among the projects shown.
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Classes
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An introductory class on the Raspberry Pi, basic electronics, Python and the Internet of Things that I taught in spring 2018, on seven Sunday afternoons - from the first LED on a breadboard to a reaction game with buttons, LEDs and an LCD display. With all slides and programs.
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Where It Started
My Busch Microtronic, 1984
My place in 1988, with the Amiga 500
My place in 1988
The story is told in 25 Years of Home Computing.
My Collection
My collection of vintage home computers, and a more recent picture gallery of it, from April 2023.
I once owned a Symbolics 3645, from 1999 to 2003! Sadly, the machine is no longer with me. Here is the picture gallery of my Symbolics 3645 Lisp Machine.