OpenOS II

OpenOS II runs on the RISC-V processor. It is a small operating system with a shell and programs written in Lua. It should feel fairly familiar if you've used OpenOS before. It needs far less memory and storage than Linux, but has no networking.

Parts

Build the computer as described in getting started, using these parts:

- 1x computer

- 1x RISC-V processor

- 1x Sedna Firmware flash memory, crafted from flash memory and a RISC-V processor

- 1x OpenOS II hard drive, crafted from a 2M hard drive and a RISC-V processor

- 1x 2M memory

Starting Up

Power the computer and turn it on. OpenOS II boots and shows its prompt, / # . There is no login, there are no users. The prompt shows the current directory. Well done, you now have a computer that's ready for use!

The System

The shell works much like one would on Linux:

- ls /bin /mnt/builtin/bin lists the installed programs. Most programs print their usage with --help.

- Up and Down go through the history, Tab completes commands and paths.

- | passes the output of one program to the next, > and >> write it to a file, < reads from one.

- ;, && and || chain commands. * and ? match file names.

- cmd & runs a command in the background. jobs lists these, kill ends one.

- Ctrl+C stops the running program.

- To turn the computer off, run shutdown. reboot restarts it.

Commands placed in /.shrc run whenever the shell starts, e.g. aliases (alias ll='ls -l') or a keyboard layout.

Writing Programs

To edit a file, run edit <file>. Ctrl+S saves, Ctrl+W closes.

A program is a Lua file. Use lua <file> to run them, lua alone starts the interactive prompt. Programs in /bin, /mnt/builtin/bin and the current directory run by name, without the .lua extension. The program gets its arguments as ...:

for i, name in ipairs({...}) do

print(i, name)

end

require loads libraries from /lib, from the built-in file system at /mnt/builtin/lib/lua, and from the current directory.

Drives

The boot drive is /dev/vda. Additional hard drives, disk drives and flash drives follow as /dev/vdb, /dev/vdc and so on.

Drives are mounted automatically, at /mnt/<label> if the medium has a label, else at /mnt/1, /mnt/2 and so on.

A new drive needs a file system first. Run format /dev/vdb to create one, optionally passing a label as a second argument. It's also possible to use label to change the label later. Formatting a drive erases all data on it!

Floppies can be swapped at any time. Close open files on a floppy before removing it, to avoid data loss.

Devices

To control devices such as the redstone interface, use the devices library, see the high-level API. lsdev lists the connected devices.

The built-in file system at /mnt/builtin also provides import and export for the file import/export card, and the robot library for robots.

The sound card, projector and keyboard are available to programs. See their respective entries on how to use them.

Clocks

Computers provide two hardware clock (RTC) devices. The first one counts time in a scale most users will think in. It is used by default, for example by date and time. The second one measures time as it works in the world the computer runs in. To obtain the current world time, use date -w.