The author describes their experience troubleshooting an IBM 5150 motherboard that failed to POST. After initial tests indicated some BIOS activity, they used an MCL86+ board for further diagnostics. The investigation revealed a s...
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The author discusses modifications made to the MCL86+ to run on the IBM PCjr, including adding 8088 minimum mode support and PCB modifications. The project aims to achieve cycle-accurate performance, with claims that the PCjr can ...
MCL_PetDoctor is an open-source diagnostic tool for Commodore PET that tests motherboard components and allows for custom tests via Arduino IDE.
Replacing the Commodore PET 4016's CPU with an MCL65+ 6502 board significantly enhances its performance and allows for direct program execution from memory.
The MCLV20_Max is a Teensy 4.1-based software-defined drop-in CPU replacement for the Intel 8088 used in vintage IBM XT’s. It emulates the full Intel 8088 instruction set as well as the additional 80188 and V20 opcodes. It also mi...
XTMax is a software-defined 8-bit ISA card using Teensy 4.1 microcontroller board that provides the functionality of three vintage ISA cards. It expands motherboard RAM up to 640 KB, adds up to 16 MB of Expanded RAM, supports 320 ...
0MCLV20_Max now able to boot from MicroSD
2025-07-15 •
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The MCL6809 is a Motorola MC6809E cycle-exact, drop-in emulator which uses a Teensy 4.1 and a small PCB. It supports all of the undocumented opcodes including HCF – Halt and Catch Fire. It can boot Extended BASIC and run a number ...
0HP 1607A UPDATE
2024-03-03 • electronics microcore labs hp printers
The author fixed a non-functional HP 1607A by identifying and replacing a missing 100 khz clock and a faulty inductor.
The author acquired a vintage HP 1600A/1607A logic analyzer set and managed to get the 1600A running and functional. They used a Teensy 4.1 to provide data signals and clock outputs, and also enabled the MAP function to write to t...
The author encountered a display issue with their IBM PCjr, missing some colors, mainly blue. They took the display apart and found a short in one of the capacitors on the neck board. After snipping one of the capacitor's legs, th...
The MCL68+ is a Motorola 68000 drop-in replacement emulator using the Teensy 4.1 to emulate the microprocessor and local bus interface at full speed. It is the most ambitious drop-in emulator designed by the author and is able to ...
The text discusses the author's experience with acquiring and repairing an Apple III, including replacing the 6502 with an MCL65+ to debug the motherboard, tracing the net back through every IC in the path, and fixing issues with ...
The project uses MCL65+ to convert an Apple II into an Apple 1 by replacing the Apple II BIOS with Woz's Monitor. The MCL65+ uses a Teensy 4.1 to emulate the 6502, Apple I PROMs, 8 KB of RAM, and conversion routines for video disp...
The author used a MCL86+ to emulate the Motorola 68000 in place of the Intel 8088 in the IBM Personal Computer. They used Gordon Brandley’s 68K BASIC to run on the 68000 emulation. The project showed that there was not much of a p...