Ask HN: Weirdest Computer Architecture?

"Computer architecture" is used in several different ways and that can lead to some very confusing conversations. Your proposed stack has some of this confusion. Some alternative terms might help:

"computational model": finite state machine, Turing machine, Petri nets, data-flow, stored program (a.k.a. Von Neumann, or Princeton), dual memory (a.k.a. Harvard), cellular automata, neural networks, quantum computers, analog computers for differential equations

"instruction set architecture": ARM, x86, RISC-V, IBM 360

"instruction set style": CISC, RISC, VLIW, MOVE (a.k.a TTA - Transport Triggered Architecture), Vector

"number of addresses": 0 (stack machine), 1 (accumulator machine), 2 (most CISCs), 3 (most RISCs), 4 (popular with sequential memory machines like Turing's ACE or the Bendix G-15)

"micro-architecture": single cycle, multi-cycle, pipelines, super-pipelined, out-of-order

"system organization": distributed memory, shared memory, non uniform memory, homogeneous, heterogeneous

With these different dimensions for "computer architecture" you will have different answers for which was the weirdest one.

Weird for its time, not so much today

Of course there are things like the molecular mechanical computers proposed/popularised by Eric Drexler etc.

I think Transport-triggered architecture (https://en.wikipedia.org/wiki/Transport_triggered_architectu...) is something still not fully explored.

These aren't implemented in hardware, but they're examples of esoteric architectures:

zk-STARK virtual machines:

https://github.com/TritonVM/triton-vm

https://github.com/risc0/risc0

They're "just" bounded Turing machines with extra cryptography. The VM architectures have been optimized for certain cryptographic primitives so that you can prove properties of arbitrary programs, including the cryptographic verification itself. This lets you e.g. play turn-based games where you commit to make a move/action without revealing it (cryptographic fog-of-war):

https://www.ingonyama.com/blog/cryptographic-fog-of-war

The reason why this requires a specialised architecture is that in order to prove something about the execution of an arbitrary program, you need to arithmetize the entire machine (create a set of equations that are true when the machine performs a valid step, where these equations also hold for certain derivatives of those steps).

A multi-core Propeller processor by Parallax (https://en.wikipedia.org/wiki/Parallax_Propeller) in which multitasking is done by cores (called cogs) taking turns: first, code is executed on the first cog, then, after a while, on the second, then on the third, etc.