#urisc

DawnOS is a new operating system designed to not only do away with the inefficiencies of mainstream OSes like Windows, but “to liberate people from the imperialistic oppression" of Intel. Its creator, who goes only by Geri, built it on a subleq chip, with subleq a “One Instruction-Set Computer” (or OISC), a programming language/architecture with only a single command. This means the language lacks goto and while for flow control, or if for branching, or even increment, replacing them all with only a single operation -- yet it is Turing Complete, capable of supporting an entire operating system. I spoke with the creator of DawnOS, and the text of our interview runs below, but it may be helpful first to have an introduction to subleq.

The SUBLEQ language

OISCs (pronounced “whisks”) have commands that effectively combine some form of flow control, branching, and data manipulation. Often this happens by conflating the program and the memory space, effectively making it a self-modifying program. One can think of a OISC as an extreme form of RISC architecture (they are sometimes called URISCs for Ultimate Reduced Instruction Set Computer). In RISC architectures, the binaries break down to a much longer list of machine operations, but they take fewer transistors to run, and can be pipelined due to their uniform size.

Subleq’s one command gives it its name: "SUBtract and branch if Less than or EQual." Each program is a list of numbers. Each number has two roles: it is a pointer to another place in memory, and it is also data that can being operated on. Subleq's command reads three at a time, seeing each as a pointer: think of these as A, B, and C. Subleq’s command goes to the location pointed to by A, subtracts it from the location pointed to by B, and stores that at B. If B is less than or equal to zero, it goes to the location C, otherwise it progresses to the next three numbers. For example, with this program: