Used a 74LVC245 to handle 5V reads from the EEPROM chip. All other chips running off 3.3V.

Has a web interface to pick images from the filesystem and selectively load them. Can share the sketch if anybody wants.

I don’t understand what’s going on for some reason. My power rail is only showing 1.8 V when it should be 5 V. My DC on pin number four of the LM339 is only about .7 V and I’m not getting a square wave obviously coming out of pin two I’m just getting some noise when the sign wave hits its trough. Does anybody have an idea of what’s going on here? The voltage seems to go back to normal on the positive rail if I pull out the LM339.

So I got this wired up and it works with one caveat: I have to run the "set/advance" button for the hours to wrap through a whole 12 hours, and then everything works right. I get 1,2,3,4,5,6,7,8,9,10,11,12, and repeat.

I am not that great at finding the optimal logic to get this stuff to work, but I used all the pieces that came in the kit. You can see the 74LS## next to their symbols in my diagram.

Also, because my diagram is quite a mess, I will post a Falstad file in a comment on this post that you can try in the Falstad circuit simulator.

Let me know what you think or if you see any way it could be better! My circuit shouldn't be too hard to improve...

So I think this oculd be caused by a lack of decoupling capacitors, but theres a heavy delay between the clock pulses and the updating on the 7 segment displays, ALU, registers, and RAM. I can upload more photos if that helps.

For the uninitiated: https://youtu.be/IXvEDM-m9CE?is=vGlxk-3piC6gcQkQ

I am planning on attempting a subleq build using the technique. Hoping for a very clean aesthetic. Any clean wire wrap builds i can reference for inspiration?

I am in the midst of testing all my connections, and similarly to Ben, I plan to do this by adding one bit at a time to zero to verify whether the output is correct. However, after clearing both the A and B registers and trying to add a value to the A register bits one at a time, none of the bits light up. What could the problem be?

Thanks in advance!

I seriously doubt this will ever run DooM, but it definitely can play the (almost) entire music video, with the laptop exclusively serving as a dumb terminal of sorts, through screen.

There is a little bit of desyncing, but tbh I am surprised I managed to get the video compressed enough to fit while being somewhat recognizeable, and have the decoding/video-playing logic in the same 32k of EEPROM as the entire video.

Curiously enough, it fits into ROM by: 1. downscaling to 40x30, 2. applying canny edge detection to get only the outlines (sending less characters over serial is more better when you try to get a "viewable" framerate), 3. Run Length Encoding it as tightly as possible (meaning the video is black and white, which allows for compressing 127 consecutive white pixels into a single byte) and storing it in binary. 4. The decoding logic just needs to deconstruct the RLE data, and send it in order to the right place of the terminal using ANSI escape characters

I'm sure someone wayy smarter than me can figure out how to get the video played back with a more consistent framerate (so it stays in sync with the music), but for now, I am happy with the result!

The video shows my custom PCB running it, but it should run unmodified on the 6502 breadboard computer as well, since they are electrically wired the same.

I'd be curious on what other cool demos could run on this hardware without changing clock speed or similar :)

Hello there i am again!

I was building the clock module and ran into this really weird issue where the initial clock output of the astable 555 timer is heavily delayed after the logic gates... But i suspect that that is not how its supposed to work and even i know that with my limited knowledge on this stuff.

Help is greatly appreciated!!

Edit: it was accidentally connected to pin 2 instead of 3

Got impatient and hooked up the via with some jumper cables for now, but it can count!

In Ben's video, he says the hsync and vsync are active negative. However, I searched the standard, and it says active high (positive). Anyone knows what is happening?

Also, the standard says a new line starts at the beginning of the sync pulse, not the active video. It matters when we are considering when exactly the vsync should be active, relative to the hsync signal.

document:
https://glenwing.github.io/docs/VESA-DMT-1.11.pdf

The pins on (what i think is) the ram came bent,

The ram was half off the foam...

Should I just try to bend them back or something else?

edit: I was luckily able to bend them back, and one problem remains 😅 the clock kit came with the UK adapter (I didn't buy them it was a present) and I'm in the eu (nl), so where could I get a replacement for the eu (with not 200 euro shipping costs)

Hey folks, I’m really enjoying learning this stuff but I’m having an issue the second I plugged in my LM339 my voltage drops from 5 V down to 1.6 on my rail. Any idea why this might be happening?

As you can see in the pictures, I’m getting a reading of 5 V when I don’t have the rail attached to pin three but I’m getting approximately 1.8 when I do have that pin attached

I watched the first video, the most challenging part of this project, and attempted to figure out how I could create something similar myself.
Unfortunately, delivery isn’t available to my country and some parts on the list are difficult to find locally. Therefore, I’ve opted for more readily available 4000-series ICs.
Here is my result. I’m waiting for the rest of the videos so I can compare and improve my version. And thinking about adding an alarm to it.
Thanks a lot Ben for another fantastic project!

I'd like to buy ben's clock kit from his recent videos but it doesn't seem like he has the full videos published. Does the kit itself come with a manual to build the clock, or do I just have to wait for the video set to come out?

Recently started designing a 6502 computer, I'm a beginner in electronics so I can make some bad mistakes.

I need to know if any damage will be caused, if any component or system is missing, if a pull up or down resistor or possible short circuit prevention or decoupling capacitor is needed.

Removing false and unwanted,rapid on-off transitions caused by a mechanical switch.

A mechanical button physically bounces,when we press once,electrically it looks like 0→1 transition

Actually: 0→1→0→1→0

These rapid changes are called bounce.

De bouncing filters those noisy signal so that system sees

0→1(one stable transition)

https://youtu.be/KtBByCyRegc?si=ycgkzzSKwX906cN9

After finishing the build I got tired of toggling programs into RAM one byte at a time with the DIP switches. Every solution I found online used a microcontroller, and I wanted to stay in the spirit of the original project, so I built a bootloader out of nothing but TTL logic, EEPROMs and passives.

How it works:

A 74LS74 D flip-flop acts as a LOAD flag, preset on power-up. Its output drives A10 on the microcode EEPROMs, so the fetch & decode cycle changes depending on the mode: LOAD mode fetches from a Boot ROM instead of RAM, RUN mode is the normal fetch from RAM.

The Boot ROM holds a 16-byte bootstrap (LOAD 0 ... LOAD 14, RUN) that copies one program from a Program ROM into RAM, then clears the flag to start executing it.

A third EEPROM extends the control word from 16 to 24 bits, adding 8 new signals

(PRI PRO BRI BRO RUN NXT RES PCE) and three new instructions: LOAD, RUN and NEXT.

The Program ROM holds 16 programs, bank-switched by a 74LS161 acting as a "program pointer". Each program ends with NEXT, which resets, flips back to LOAD mode and increments the pointer — so the machine cycles through all 16 programs forever, completely on its own, from the moment you plug it in.

I also reprogrammed the 7-segment display EEPROM: the two's complement half of the table goes unused in LOAD mode, so I replaced it with animation frames and get a loading animation while a program is being copied:

https://raw.githubusercontent.com/marcoava00/8bit-computer-custom-bootloader/main/docs/img/loading.gif

The case in the video is mine too: I designed it in Fusion and 3D printed it in a semi-transparent material, with a door and plexiglass. That's what gives the glow you see here in the dark.

Full write-up, KiCad schematics and all the Arduino sketches:

https://github.com/marcoava00/8bit-computer-custom-bootloader

Finally got the clock module to work! First attempt didn’t work as nicely, and turns out the breadboard I bought was just crappy… Also, the little loop of loose wire is simply because I didn’t have an appropriate toggle switch handy…

Pretty much just the title. I initially always tied it to ground when troubleshooting because I never had any need to halt the clock, but not that it’s connected to the control word at the bottom, no matter high or low it does nothing and the clock stays on. I’ve double checked all the proper connections and the wires seem to be in the right place so I thought I'd consult Reddit, thanks!

I am new to electronics and was recently watching the series on building a digital clock. On this circuit I probed the diode on the left (the one highlighted with blue) and resistor on the right. In both the scopes the waveform of current is as expected only in the positive cycle but I don't quite get the waveform of voltage of diode why does it show a voltage spike in the negative cycle and a flat line on the positive cycle.

When I completely remove the address and data lines from the sketch, it catches the clock pulses as it should. When I put the data lines back into the sketch and wire them, I get bursts. The Arduino records multiple clock pulses with random data when though I only pulsed the clock once.

I'm using a 65C816S

Ben-Eater-65C02-Programs/LCDInit.asm at main · 2E26/Ben-Eater-65C02-Programs

After spending a few months writing a complete program to write program data to the EEPROM, I've finally put it into action and got it doing something. All this does is print a message on the screen and continuously display a loading bar. However, it contains a complete function library for LCD display as well as a millisecond delay routine that's pretty accurate.

My next steps are to build a monitor for the stock BE6502. It'll use the push buttons and display everything on the LCD. The goal is to build something that everybody can use with only the stock hardware. I'm also planning on a modification to expand SRAM to 24K vice the stock 16 and also planning to buy a 20 x 4 LCD to upgrade the display.

For now, I want to go back to my x86 roots and write a PC-side program to read raw binary files and pass them onto the PIC16F877A for automatic programming. The programming app I wrote for the PIC works very well, but it's a pain in the butt to type in your program one byte at a time. Maybe I should make a video on how to use it.

If one input is a Data Signal and the second input is an Enable Signal, then when the Enable signal goes HIGH, the data passes through to the output.

[ISSUE FIXED] I have come back to my 8-bit circuit after a month away and came across some problems after testing the register. I have decided to troubleshoot using register A with the bus to start, moving onto register B with the bus from picture 6. In each picture, I have included the "settings" and output.

In picture 3, I tried load on low, however all lights went out. I think this is due to a compatibility issue with inputs set high, but the enable was set high so no values should be sent to the bus?

I do not have any power supplying the bus outside of the outputs of the LS245. I am unsure why the Bus LEDs light up as soon as power is supplied to the clock circuit and register.

IN 1Hz clock pulse

Building a 1Hz clock pulse circuit using LPC2148 ARM7 for my custom 8-bit project!