Category Archives: logic

Pushing Pixels To A Display With VGA Without A PC

[Ben Eater] is back with the second part of his video series on building a simple video card that can output 200×600 pixels to a display with nothing but a VGA connection, a handful of 74-logic chips and a 10 MHz crystal. In this installment we see how he uses …read more

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Posted in 74 series logic, breadboard, breadboard hacks, classic hacks, logic, retrocomputing, Tech Hacks, vga, video card | Leave a comment

A Full-Stack Web Browser

Interviewing to be a full-stack engineer is hard. It’s a lot harder than applying for a junior dev job where you’re asked to traverse a red-black tree on a whiteboard. For the full-stack job, they just give you a pile of 2N2222 transistors. (The first company wasn’t a great fit, …read more

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Posted in 2019 Hackaday Prize, hardware, logic, rs232, The Hackaday Prize, ttl, vga | Leave a comment

Behind The Pin: Logic Level Outputs

There is one thing that unites almost every computer and logic circuit commonly used in the hardware hacking and experimentation arena. No matter what its age, speed, or internal configuration, electronics speak to the world through logic level I/O. A single conductor which is switched between voltage levels to denote a logic 1 or logic zero. This is an interface standard that has survived the decades from the earliest integrated circuit logic output of the 1960s to the latest microcontroller GPIO in 2018.

The effect of this tried and true arrangement is that we can take a 7400 series I/O …read more

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Posted in behind the pin, digital logic, Engineering, Hackaday Columns, logic, Original Art, parts | Leave a comment

Cigar Box Synth is a Fun Time

It’s fair to say that the groovebox market has exploded. Store shelves are overflowing with the umpteenth releases from KORG’s Volca line and the latest Pocket Operators. These devices often feature a wide array of tones in an enticingly compact and attractive package, but is it possible to build something similar at home? As [lonesoulsurfer] relates, it certainly is.

The Cigar Box Synth is, well… a synth, built in a cigar box. Based upon a 555 & 556 timer, and a 4017 decade counter, it provides a wealth of beepy goodness all crammed into a neat wooden package. We dig …read more

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Posted in logic, musical hacks, syhthesizer, synth | Leave a comment

An 8-Bit ALU, Entirely From NAND Gates

One of the things that every student of digital electronics learns, is that every single logic function can be made from a combination of NAND gates. But nobody is foolhardy enough to give it a try, after all that would require a truly huge number of gates!

Someone evidently forgot to tell [Notbookies], for he has made a complete 8-bit ALU using only 4011B quad NAND gates on a set of breadboards, and in doing so has created a minor masterpiece with his wiring. It’s inspired by a series of videos from [Ben Eater] describing the construction of a computer …read more

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Paper Circuit Does Binary Math with Compressed Air

Most of us can do simple math in our heads, but some people just can’t seem to add two numbers between 0 and 3 without using paper, like [Aliaksei Zholner] does with his fluidic adder circuit built completely of paper.

There’s some good detail in [Aliaksei]’s translated post on the “Only Paper” forum, a Russian site devoted to incredibly detailed models created entirely from paper. [Aliaksei] starts with the basic building blocks of logic circuits, the AND and OR gates. Outputs are determined by the position of double-headed pistons in chambers, with output states indicated by pistons that raise a …read more

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Posted in logic, misc hacks, OR, paper, Pneumatics | Leave a comment

Relay Computing

Recently, [Manuel] did a post on making logic gates out of anything. He mentioned a site about relay logic. While it is true that you can build logic gates using switch logic (that is, two switches in series are an AND gate and two in parallel are an OR gate), it isn’t the only way. If you are wiring a large circuit, there’s some benefit to having regular modules. A lot of computers based on discrete switching elements worked this way: you had a PCB that contained some number of a basic gate (say, a two input NAND gate) and …read more

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Posted in logic, logic gates, misc hacks, mux, relay, relay computer, relays | Leave a comment

Yes, You Can Reverse Engineer this 74181

[Ken Shirriff] is the gift that keeps on giving this new year. His latest is a reverse engineering of the 74181 Algorithmic Logic Unit (ALU). The great news is that the die image and complexity are both optimized for you to succeed at doing your own reverse engineering.

We have most recently seen [Ken] at work explaining his decapping and reverse engineering process at the Hackaday SuperCon followed soon after by his work on the 8008. That chip is crazy with complexity and a die-ogling noob (like several of us on the Hackaday crew) stands no chance of doing more …read more

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Posted in ken shirriff, logic, logic gates, reverse engineering, silicon | Leave a comment

Taking It To Another Level: Making 3.3V Speak with 5V

If your introduction to digital electronics came more years ago than you’d care to mention, the chances are you did so with 5V TTL logic. Above 2V but usually pretty close to 5V is a logic 1, below 0.8V is a logic 0. If you were a keen reader of electronic text books you might have read about different voltage levels tolerated by 4000 series CMOS gates, but the chances are even with them you’d have still used the familiar 5 volts.

This happy state of never encountering anything but 5V logic as a hobbyist has not persisted. In recent …read more

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Posted in level shifting, logic, logic levels, parts, ttl | Leave a comment