~~hero-subtitle An Embedded, Variable Instruction Length bit-serial CPU architecture.~~

• The instruction encoding is very simple - in fact, it is the simplest that instruction encoding can possibly be.
  • 0 is NOP; 1 is OP.
    • If you hit NOP, go to next bit and continue.
    • If you hit OP, then go to next bit, and see what operation it is.
    • After OP you then have eight classes of instruction, given by three binary decisions: memory/register; ALU/copy; I/O ports/bus memory.
• In effect, it is a 1-bit CPU architecture that does nothing, if all you feed it is zero bits.
• It can be self-clocking, as the instruction encoding is meant to not enable long run-lengths of the same bit.
  • Except 0, which is not only NOP, but also static, default, halt.
  • A 1 following the NOP acts as both the clock and interrupt pulse.
• The goal here isn't to run fast, or even run well.
  • it is minimal computing hardware without going to absolute turing tarpit status.
• Bit-serial CPUs have a handful of advantages:
  • Bit-serial CPUs are minimal in terms of cost and requirements.
    • Sometimes they don't even need a +Vcc; they'll work on quiescent current and operate with bus voltage.
      • Obvious power-saving benefit there, too.
  • A bit-serial CPU embeds well for minimal state control and programmable logic in places you wouldn't expect.
    • Places like an addressible, color LED cell, similar to the WS2812 and similar series.
  • If you need complex, programmable machinery, with memory, in an extremely limited die space, a bit-serial architecture can make it work.
    • I'm thinking something along the terms of targeted drug delivery. You have a tiny, biocompatible and inert chip with minimal, energy harvesting running current, a few hundred bytes of ROM and RAM, an electrochemical enzyme sensor on a digital port, and another protein structure that unfolds when an electric charge is applied, releasing a molecule of targeted therapy into the surrounding tissue.
      • You wouldn't be able to embed much more than a bit-serial ISA in there, but you need a programmable computer to determine what the hysteresis and trigger values are for the input sensor molecule.
      • So, if you're planting several hundreds of this chip onto dose-regulated particles, it can sense when it needs to release the drug more efficiently than state machinery or a logic circuit.
    • The complexity space for a bit-serial micro falls squarely where silicon real estate is at a premium, and where a logic circuit would take significantly more space to implement than a programmed memory cell.
    • A bit-serial computer uses less space and energy to progress through complex processing with memory, like the case mentioned above.