subverge

Decisions

Each of these is a choice the system makes and what follows from it. They go with the rules on the design page.

omega is a stack language

A line is split on spaces and brackets and evaluated from left to right, so precedence never comes up and a word's arguments are the values before it. Programs, commands and saved state share one syntax, which means the saved form of a world is its own source (saving). calc is the one place that parses infix, for arithmetic you want to type as usual.

Everything runs in ring 0

The prompt reaches all memory, every I/O port and every disk, and a call into the kernel is a function call. A line can do anything the hardware allows, and so can a mistake: a bad poke or out is outside the transaction and can stop the machine (smarties, expectations).

Every line is a transaction

A line works on a copy of the world. If every word succeeds the copy becomes the new world and the old one goes into the history, and if a word fails the copy is thrown away. The same history gives back and redo, 64 worlds deep (transactions, back). Printed text, the screen, the machine and root edits that already built are outside it.

The disk has no files

An installed drive has no partitions and no filesystem. The kernel, root and each shell's world are written at fixed sectors, as omega source, so an image can be read with a hex editor (disk layout). Nothing is allocated and nothing has a path.

The JIT compiles on the second run

The first run of a quote is interpreted, and the second compiles it to x86-64. Compiled code and the interpreter give the same results, including the switch to bignums on overflow, so jit-off can be used to check one against the other (JIT).

Root is rebuilt from source

The programs in root are omega source that is built at boot and again after every edit. An edit that fails to build leaves the old root in place. A new root becomes visible to all four shells at once (root build).

Four shells

The kernel runs exactly four shells at the same time under a timer-driven scheduler. Each has its own world, history and key queue and a 256 KiB kernel stack. They share root, the heap and the hardware (tabs, scheduler).

The help is part of the kernel

The pages are text in the kernel image, found by name in a table built together with it. They match the build that is running, and they are available on the live ISO with no disk attached. docs and "name" doc open them in a pager that draws on the text screen (help).

The machine is QEMU

Every driver is written for the hardware QEMU provides: the PIT and PICs, a PS/2 keyboard and mouse, IDE disks through the legacy ports, and a VGA card with an optional Bochs graphics mode.

What is not there yet

UEFI booting, USB, AHCI, networking, sound beyond the PC speaker, floating point numbers and more than one CPU core are on the roadmap.