This is a design for a simple 8085-based single-board computer on a breadboard. It was started as a way to run the software from an old Netronics Explorer/85 board from the early 1980s. The primary purpose of the design is software compatibility, rather than building a chip-for-chip clone of the Explorer.
The Simple8085 Documentation Pages have a complete descripton of the design, plus build steps, utilities, and test programs.