“MikroLeo project files (schematic, PCB, assembler, emulator/debugger, circuit simulation file, documentation, example of programs etc). MikroLeo is a 4-bit microcomputer developed mainly for educational purposes and distributed for free under open-source licenses.
4-bit Didactic Microcomputer
The project is in the final testing stage.
This project was developed mainly for educational purposes.
I hope it will be a good learning platform for anyone who likes electronics, computers and programming.
Since my first attempts, many efforts have been made to make this project real.
It is aimed at students, enthusiasts, hackers, professors and anyone who wants to understand or improve their knowledge of electronics and learn how a simple computer works. In addition, it is also an attempt to rescue the story about the beginning of the development of integrated circuits and computers on a single chip, to demonstrate the capabilities that these machines had at that time.
It is a fully open-source hardware and software project that can be built at home. Only the printed circuit board (PCB) needs to be produced by some company.
For the next steps, an important thing is to make good documentation for MikroLeo!
Main Features:
- Implements a 4 bit CPU
- 2k x 16 ROM (up to 4k)
- 2k x 4 RAM (up to 4k)
- 4 Output Ports (16 outputs)
- 4 Input Ports (16 inputs)
- Single Cycle Instruction/RISC
- Harvard Architecture
- 3 execution modes:
- step
- 3MHz (precise time base)
- adjustable clock speed
- No MPU/MCU or complex chips
- No microcode
- Indirect addressing to facilitate the implementation of subroutines
- Program memory implemented with RAM to easy programming
- It accepts 300 and 600 mils memories (for those with old DIP versions)
- Supercapacitor or battery to keep the program in RAM (for low power version)
- It can be manually programmed by switches or via Arduino/Esp32
- Built with 74HCTxxx integrated circuits for low power consumption and compatibility with TTL circuits
- All parts are through-hole for easy assembly
- All control signals, registers and the program counter are available through the pin header connectors
- Dual layer Single board with 295.9mm x 196.9mm”