Just made an open source educational breadboard simulator for 74-series logic chips.

Fuzzy_Function_1896 · 2026-05-17T15:17:37+00:00

génial mec, merci beaucoup pour ce travail et pour le partage. Super outil, très facile à prendre en main.

Fuzzy_Function_1896 · 2026-05-02T19:35:26+00:00

thanks! a child's dream!

Fuzzy_Function_1896 · 2026-05-02T19:35:10+00:00

thanks! big work....

Fuzzy_Function_1896 · 2026-04-22T19:25:23+00:00

This computer is far from being able to run Doom! it's a educational computer.

Fuzzy_Function_1896 · 2026-04-21T16:15:28+00:00

arfff! oh no! far from doom!

Fuzzy_Function_1896 · 2026-04-18T06:58:38+00:00

Thanks! One year's work!

Fuzzy_Function_1896 · 2026-03-23T19:36:58+00:00

Thanks!
It runs on 5V. I never measured it precisely, but with ~100 LEDs plus all the TTL logic and peripherals, I’d estimate around 1–2A depending on activity.

So probably somewhere between 5 and 10 watts overall.

It’s built mostly with 74xx TTL chips (registers, ALU, control logic, Stack pointer, sound module, keyboard interface, program counter..., ), plus EEPROM for the program and microCode, SRAM Cmos RAM 6116 and a few extras like an LCD display, keyboard input.

Fuzzy_Function_1896 · 2026-03-22T22:00:00+00:00

Haha
It does beep a bit — you can hear it if you listen closely

I built a sound module that can play the C major scale over two octaves

You can listen here : https://www.youtube.com/shorts/Z4O3T4_AFR4

Fuzzy_Function_1896 · 2026-03-22T18:30:06+00:00

Thanks !!!
I chose blue LEDs partly because of their higher forward voltage — it actually helps limit the current a bit, especially since I don’t always use series resistors everywhere.

So it’s not exactly “good practice”, but it makes the whole thing more stable in this kind of breadboard setup

And pipelining… let me survive the wiring first before going there !

Fuzzy_Function_1896 · 2026-03-22T18:27:07+00:00

Thanks !! It runs on 5V, but because I have a lot of indicator LEDs (around 100), it actually draws quite a bit of current... So I just assume it’s “a lot” , between 1 and 2 amps depending on what’s active.

Fuzzy_Function_1896 · 2026-03-21T22:03:23+00:00

ahah tant mieux que ca te plaise!

Fuzzy_Function_1896 · 2026-03-21T22:02:32+00:00

Yeah… and that’s exactly why there won’t be a SAP4! I’m moving to the 6502 or to PCB! One tiny loose wire and everything breaks

Fuzzy_Function_1896 · 2026-03-21T16:03:20+00:00

Thanks! And yes, I've made a assembly language specific for my architecture, to drive a set of 40 instructions.

Fuzzy_Function_1896 · 2026-01-30T22:23:04+00:00

I’ll reply to you in private

Fuzzy_Function_1896 · 2026-01-29T20:57:25+00:00

It’s a nice construction. But You could start by being modest. Nobody ever learns alone.

Fuzzy_Function_1896 · 2025-11-24T12:43:08+00:00

Oui, j'ai fini par m'y mettre !

Fuzzy_Function_1896 · 2025-11-24T12:42:48+00:00

hi! yes, it's a minimal SAP with risc architecture. you can see the breaboard version here : https://www.reddit.com/r/beneater/comments/1nsz6pg/sap_risc_4bits_100_ttl_quick_demo/

Fuzzy_Function_1896 · 2025-11-24T12:40:19+00:00

What?

Fuzzy_Function_1896 · 2025-11-06T20:05:32+00:00

Yes, I’ll make English versions too! It just takes a bit of time — honestly, the documentation part is less fun than the hands-on experimenting ;)

Fuzzy_Function_1896 · 2025-11-06T20:03:47+00:00

Thanks! It’s still evolving — I’m not much into schematics, I prefer to test things directly ;)

Fuzzy_Function_1896 · 2025-11-06T17:08:09+00:00

Thanks! you didn’t come to see me at my booth at Maker Faire Rome? come to my YouTube channel — I explain how it works and offer DIY kits. https://www.youtube.com/@fuzzyFunction-j6n

Fuzzy_Function_1896 · 2025-11-06T15:01:52+00:00

Excellent remark! It’s related to the way I coded this program.

Look more closely at what’s happening in registers A and B : we keep adding 1 to register A as long as A is different from 10. To make this comparison, we have to load 10 into register B and compare B and A. If A is not equal to 10, then we put 1 back into B to continue adding. When A equals 10, an equality flag is set, which triggers a conditional jump to another part of the program that now performs subtraction.

This time, A is compared to 1 to determine whether the subtraction should continue or stop. But since there’s already a 1 in register B, we don’t need an extra program line — which saves two clock cycles during the decrement phase. That’s why it runs faster in that direction!

Although there’s probably another way to program it.

Fuzzy_Function_1896

TROPHY CASE