Squeezing A Minimalist 6502 Retrocomputer Onto A Single Breadboard

January 4, 2023 by Dan Maloney 9 Comments

Over the years, and especially lately, we’ve seen tons of single-board retrocomputer builds. That’s fine with us — the more, the merrier. But they all start to run together a bit, with little to distinguish between them. Not so this about-as-compact-as-possible 6502 computer that fits on a single breadboard.

Now, when you do the math, it seems like there’s no way that [Anders Nielsen] would have been able to fit even a minimal chipset onto a standard solderless breadboard. The 40-pin 6502 alone takes up nearly two-thirds of the connections available; add in equally large but necessary chips like the 6522 interface adapter, ROM and RAM chips, and some support ICs, and one breadboard isn’t going to cut it. Luckily, some frugal engineers at MOS back in the 70s came up with the 6507, a variant on the 6502 in a 28-pin DIP. The other key to this build is the 6532 RAM-I/O-timer chip or RIOT, which puts a tiny amount of RAM and some IO lines on a single 40-pin DIP. Along with a 28-pin ROM, a 14-pin hex inverter, and a little crystal oscillator, the entire chipset just barely fits on a single breadboard.

But what can this minimalist 6502 actually do? As you can see in the video below, anything a 555 timer can do, and maybe a little bit more. That’s not a dig, of course — [Anders] actually calls out his initial blinkenlight application as a little more than a glorified 555, and actually comes up with a marginally more complex application just to prove the point. The interesting part here is dealing with the constraints imposed by the limited resources available on this machine.

We’re looking forward to whatever comes next for this clever build. It’s hard to see how some of the plans [Anders] has for it will still fit on a single breadboard, though — these things tend to spread out as they go.

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A pair of purple PCB-based game controllers on a solderless breadboard

Odd Inputs And Peculiar Peripherals: The GameBug Turns Your Breadboard Into A Game Console

June 5, 2022 by Robin Kearey 1 Comment

What’s more fun than playing video games? Designing your own video game hardware, of course! If you’ve followed these pages long enough you’ll have seen dozens of great examples of homebrew hardware, and perhaps been inspired to try such a project yourself. This often starts with assembling the basic bits onto a solderless breadboard, which is fine for programming but not so great for testing: squeezing pushbuttons into your breadboard works for basic debugging, but is not very user-friendly or reliable. A better solution can be found in [Dimitar]’s GameBug: a set of breadboard-compatible joypad-like controllers.

The GameBug’s design excels in its simplicity: a miniature analog joystick, four buttons arranged in a diamond pattern, a shoulder button and two sliding switches are sitting on a neat purple PCB. On the bottom are two rows of pin headers to ensure a snug fit on your solderless breadboard. There’s even a little vibrating motor for haptic feedback.

Interfacing with the GameBug is simplified by the integrated readout electronics. A Schmitt trigger-based debounce circuit ensures clean signals from all the pushbuttons, while a motor driver chip provides stable current to the haptic feedback system. An RGB LED can be used as yet another user feedback device, or simply for decorative lighting.

All design files are available on [Dimitar]’s GitHub page, along with an Arduino sketch to help you try out the GameBug’s functionality. Having a proper gamepad might come in handy with breadboard-based game systems like Tiny Duck Hunt or this impressive mess of wires that makes up a Colecovision.

3D Printed Breadboard Helper Makes Wiring Neater And Easier

February 23, 2020 by Al Williams 25 Comments

Breadboards make it simple to prototype and test circuits. If you use flexible wires with pins to make connections, it usually results in a rat’s nest. For many of us, using solid wire makes a rat’s nest, too. However, the very neat among us will cut solid wire to just the right length and strip just the right amount of wire and lay the wires very flat and neat along the board. [Moononournation] did a 3D print that makes the latter method much easier. You can find his Breadboard Wire Helper on Thingiverse and see a video, below.

The idea is simple: start with a piece of wire stripped on one side, then count out the number of holes it needs to traverse and push the stripped end through the hole. Trim the wire to fit. To complete the other side, lay the wire flat along the tool to the edge. Now you can see where to strip that side of the wire. After you remove the insulation, you can bend the wire down and cut the wire to fit. Now you have a perfect size and shape wire to place in the actual breadboard.

Granted, this isn’t that hard to do with the existing breadboard if it isn’t too packed. You could even use a spare breadboard. But it is a little easier to trim the wire to the right size with this jig. If you don’t want to 3D print it, you could probably pull the tape off the back of a cheap board and remove the springs to get a similar effect.

So while this little tool probably won’t change your life, it might make it a little easier. What other tools do you use when breadboarding? Let everyone know in the comments.

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Simple Trick For LEDs On Solderless Breadboards

June 9, 2019 by Ted Yapo 39 Comments

Sometimes the most useful hacks are also the simplest ones. A case in point is the LED and resistor assembly that [Skippy] recently posted on his blog. The idea is to solder up some pre-made indicators with integrated resistors to save space on the breadboard when prototyping — instead of four slots, you only use two per LED. This is about as easy a trick as you can imagine, but it has the hallmark of a classic hack: a high utility-to-work ratio.

The deluxe assembly uses a two-pin header as a base to plug into the breadboard. This, of course, could be optional since some breadboards have a memory for the widest pin previously inserted — using header pins may eventually make the slots a little flaky for smaller component leads. But, if you’re mostly using header pins in the breadboard anyway, this is a good way to avoid kinking the leads.

While there are LEDs available with integrated dropping resistors, building your own means you can use whatever LEDs you prefer — or simply have on hand — and adjust the resistor value for different voltages or to adjust the brightness. And for those of you who plug in LEDs without current-limiting resistors, we’re going to assume that you’ve thoroughly researched whatever is driving them and done the math to ensure they’re safe. Or not: they’re your LEDs after all.

We previously featured a no-solder breadboarding trick for SMD LEDs. What’s your favorite solderless breadboard hack? Let us know in the comments below.

Thanks to [Roboteernat] for the tip!

The Solution To Oversized Dev Boards: A Literal Hack

August 27, 2018 by Brian Benchoff 47 Comments

Oh, there was a time when you could prototype just about everything on a breadboard. The CPU in your computer came in a DIP package, and there were no BGA packages. to be found anywhere. In the forty years since then, chips have gotten smaller, packages have gotten more cramped, and you can barely hand-solder the coolest chips anymore. No worries — companies are still spitting out dev boards with 0.1″ headers, but there’s a problem: they don’t fit on a solderless breadboard. They’re too wide. Our world is falling apart.

[Luc] had a problem when he was playing with a few NodeMCU dev boards. These are too wide for a breadboard. [Luc] came up with not just one solution, but two. This is how you prototype with dev boards that are too large.

The solution came to [Luc] when he realized the center of every breadboard has no electrical connections, and was simply held together by a little piece of plastic. Yes, he took a hacksaw to the breadboard. This is technically a hack.

With two halves of a solderless breadboard torn asunder, [Luc] had an easy way to prototype with dev boards that are just too wide. But there is a simpler solution [Luc] realized after he destroyed a breadboard: those ubiquitous solderless breadboards have detachable power rails. If you simply take one of those power rails off, you have an easy way to use two breadboards across a module that’s too wide for one solderless breadboard.

Is this a hack? Oh, absolutely. [Luc] used a hacksaw. It’s also a nice reminder of a common trick that the noobies might not know. Thanks for that, [Luc].

Solderless Breadboard Parasitics

January 19, 2016 by Al Williams 42 Comments

Solderless breadboards are extremely handy. You always hear, of course, that you need to be careful with them at high frequencies and that they can add unwanted capacitance and crosstalk to a circuit. That stands to reason since you have relatively long pieces of metal spaced close together — the very definition of a capacitor.

[Ryan Jensen] did more than just listen to that advice. He built a circuit and used a scope to investigate just how much coupling he could expect with a simple digital circuit. Better still, he also made a video of it (see below). The test setup shows a single gate of a hex Schmitt trigger inverter with a sine wave input. The output transitions ring and also couple back into the input.

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Literal Breadboard Hack Forces It To Accept Dual Pin Headers

August 18, 2015 by Al Williams 37 Comments

Usually when there is a clear demand for something, some entrepreneur will fill that demand. Unfortunately, no one seems to think there’s a need for a solderless breadboard product that can handle boards that have a dual row header. These devices have 0.1″ spacing in both directions, so while they will fit in a standard breadboard, the contacts will short out the adjacent pins on the device, which makes it worthless.

[Baz] needed to connect an RF24L01 module to a breadboard. Instead of connecting leads to the device or devising a breakout board, [Baz] actually hacked his breadboard. To make an area to plug in a dual row device, he took the breadboard apart, pulled the spring contacts, cut them, and then put them back in.

Of course, you have to make sure the cut is wide enough that the two parts of the spring won’t touch. It looks like [Baz] used a small screwdriver to help the springs keep their shape and cut them with simple diagonal cutters.

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