Periwinkle: A CPU with a Single Instruction

Regardless of the manufacturer, the number of cores, or the clock speed, there are other fundamental aspects that define a processor's design, and one of them is the instruction set. You've likely heard of things like RISC and CISC, but there's also OSIC, or "One Instruction Set Computer". It's a processor with a single instruction, backed by a specific number of registers. One such processor is Periwinkle, designed by Ike T. Sanglay Jr. in 2016.

RISC and CISC

Your desktop computer likely has a processor based on CISC, or "Complex Instruction Set Computer". Moving to mobile devices, ARM architectures are RISC, or "Reduced Instruction Set Computer". Pitting one instruction set against the other doesn't make much sense these days, as each has found a space that allows it to develop almost completely. However, RISC and CISC aren't the only ones.

Periwinkle: A One-Instruction CPU

Let's look at the case of Periwinkle, a personal project by Ike T. Sanglay Jr. that dates back to 2016. Periwinkle (from the periwinkle flower, a name given by Ike's girlfriend) is an OISC processor, or "One Instruction Set Computer". That means it has a single instruction: moving literal values to a register, or moving a register's value to another.

The word "register" is key here, because we see several registers where we might expect instructions. The official post explains the role of each register, starting with the program counter (counts up to 32 bits, and moving -1 there makes it halt), a random number generator (creates a 32-bit number on each call), a NULL register used to clear items from general-purpose registers, and more than a dozen and a half reserved registers, in case Periwinkle ends up in a microcontroller or something similar.

What does that mean? That right now, Periwinkle is little more than an educational processor, written in a virtual machine. At the end of November, Ike suggested he could load the virtual machine executable and the assembler, but the big question is, for what platform? The assembler was developed in F-Sharp, so it would work anywhere with the .NET Framework, or a bit of Mono.

Official site: Click here

Source: Hackaday