With only 2K lines of code, egos-2K implements microSD driver, tty driver, interrupt handling, address translation, process scheduling and messaging, system call, file system, shell, seven user commands and mkfs/mkrom tools.

The earth and grass operating system (EGOS) is our teaching OS at Cornell. It has three layers:

• 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 and system calls
  • inter-process communication
• The application layer provides file system, shell and shell commands.

This RISC-V version of EGOS is minimal in order to help students understand the complete picture.

# Count lines of code excluding README.md and USAGES.md
> cloc egos-riscv --exclude-ext=md  
      52 text files.
      52 unique files.
       7 files ignored.

github.com/AlDanial/cloc v 1.82  T=0.02 s (1842.8 files/s, 123267.6 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
C                               31            435            437           1560
C/C++ Header                    12             76            102            322
Assembly                         2              4             14             61
make                             1             11              0             55
-------------------------------------------------------------------------------
SUM:                            46            526            553           1998
-------------------------------------------------------------------------------

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

• 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., balena Etcher)

For compiling and running egos-riscv, please read USAGES.md. The documentation further introduces the teaching plans, architecture and development history of egos-riscv.

For any questions, please contact Yunhao Zhang or Robbert van Renesse.