With only 2K lines of code, egos-2000 implements boot loader, microSD driver, tty driver, memory paging, address translation, interrupt handling, process scheduling and messaging, system call, file system, shell, 7 user commands and the mkfs/mkrom tools. It runs on a $129 small development board.

# Count lines of code excluding references and README.md
> cloc egos-2000 --exclude-ext=md
......
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
C                               33            452            461           1566
C/C++ Header                    11             75            102            311
Assembly                         3              6             24             68
make                             1             11              0             55
-------------------------------------------------------------------------------
SUM:                            48            544            587           2000 << exactly 2000!
-------------------------------------------------------------------------------

EGOS-2000 and EGOS are the two teaching operating systems used at Cornell. They have the same architecture.

• The earth layer implements hardware-specific abstractions.
  • tty and disk device interfaces
  • cpu interrupt and memory management interfaces
• The grass layer implements hardware-independent abstractions.
  • processes, system calls and inter-process communication
• The application layer implements file system, shell and user commands.

• an Artix-7 35T Arty FPGA development board
• a microUSB cable (e.g., microUSB-to-USB or microUSB-to-USB-C)
• [optional] a microSD Pmod, a microSD reader and a microSD card (e.g., Sandisk, Samsung or PNY)

• SiFive freedom riscv-gcc compiler
• Vivado lab solutions or any edition with the hardware manager
• a software to connect with ttyUSB (e.g., screen for Linux/Mac or PuTTY for Windows)
• [optional] a software to program a disk image file to the microSD card (e.g., dd or balena Etcher)

For compiling and running egos-2000, please read USAGES.md. This document further introduces the teaching plans, architecture and development history of egos-2000.

The RISC-V instruction set manual introduces the privileged registers used by egos-2000. The SiFive FE310 manual introduces the processor used by egos-2000, especially the GPIO, UART and SPI bus controllers.

For any questions, please contact Yunhao Zhang.