July 17, 2026
8-bit beauty, typo tragedy
Show HN: Simulator for a custom 8-bit discreet logic computer
Retro computer simulator has fans swooning, nitpickers pouncing, and everyone clicking Run
TLDR: A creator built an interactive simulator for a homemade old-school computer, letting people watch every part of it run step by step. Commenters loved the polished look and peek-inside design, but also sparked mini-drama over realism, beginner friendliness, and one very public spelling correction.
A maker dropped a browser-based simulator for a homebrew 8-bit computer built from separate logic chips, and the crowd reaction was half wholesome applause, half delightfully nerdy chaos. The big draw is that you can poke around every moving part live: load a program, step through it, watch signals change, and basically play computer detective in real time. For people who love seeing how the machine "thinks," this thing hit hard.
The loudest praise was for the slick, toy-box feel of the interface. One commenter gushed that the UI and the whole philosophy were great, then immediately asked for more eye candy: why not hook it up to a virtual screen so the little computer can draw something fun? Another said it goes beyond older machine simulators because you can inspect each chip's behavior as the whole system runs. Translation for non-hardware people: this isn’t just a fake old computer, it’s a glass-walled one.
But because this is the internet, the tiny drama arrived right on schedule. One commenter swerved away from the project itself to launch a mini spelling PSA over the title’s use of “discreet” instead of “discrete.” Yes, the comments briefly turned into a grammar crime scene. Another raised a more practical challenge: how do we know the simulated chips really act like the real thing, and can beginners please get a couple of easy demos first? So the verdict is in: people are impressed, hungry for more, and absolutely incapable of letting a typo live.
Key Points
- •The article presents MSAP-2 rev.A as a microcoded simulator for a custom 8-bit discrete-logic computer.
- •The interface includes views for programming, inspection, logic scope, power supply, schematics, terminal access, and microcode.
- •The project provides exportable hardware design resources including KiCad netlists, PCB layouts, schematics, and a block SVG.
- •The simulator exposes internal CPU state such as registers, bus values, flags, and control-word signals.
- •Users can assemble and load programs, interact through a terminal, set breakpoints, and control execution with reset, step, and run functions.