The original sources of MS-DOS 1.25, 2.0, and 4.0 for reference purposes

Microsoft BASIC for 6502 Microprocessor - Version 1.1

An Operating System for Z80 computers, written in assembly

A project to resurrect Unix on the PDP-7 from a scan of the original assembly code

Fun and Games with the Videocoreiv Quad Processor Units

Genesis development environment for Linux.

The MSX Red Book in Markdown format.

The working source code to PDP-11 Unix from 1972.

Small, discreet, complete samples for the SEGA Mega Drive/Genesis in 68000 assembly

A new 8086-based reimagining of PC DOS and BASIC

Retro Z80 CPU Board

Aventuras en Megadrive: Aprende a programar y crear juegos

My version of Flappy Bird for MSX Computers

MSX emulator written entirely in Assembly

along32.sourceforge.net; buildable on macOS, used in my co-project janka102/MASM_OSX

Addtris

A template for developing filesystem drivers for MSX-DOS 2 and Nextor

Palo Alto Tiny BASIC v3 source code by Li-Chen Wang as published in the PCC's Reference Book