DIY Core Rope Memory Z80 Demonstrator Generating A Fibonacci Sequence

October 16, 2024 by Dave Rowntree 14 Comments

We’ve seen a few retro products using core rope memory, such as telephone autodiallers. Obviously, we’ve covered the Apollo program computers, but we don’t think we’ve seen a complete and functional DIY computer using core rope memory for program storage until now. [P-lab] presents their take on the technology using it to store the program for a Z80-based microprocessor demoboard, built entirely through-hole on a large chunk of veroboard.

For the uninitiated, core rope memory is a simple form of ROM where each core represents a bit in the data word. Each wire represents a single program location. Passing a wire through the core sets the corresponding bit to a logic 1, else 0. These wires are excited with an AC waveform, which is coupled to the cores that host a wire, passing along the signal to a pickup coil. This forms an array of rudimentary transformers. All that is needed is a rectifier/detector to create a stable logic signal to feed onto the data bus.

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Improved Perfboard For Surface Mount Parts

January 9, 2018 by Brian Benchoff 26 Comments

Look through the last two decades of electronics project built on perfboard, and you’ll notice a trend. Perfboard is designed for through-hole parts, but ever more frequently, the parts we need are only available as surface mount devices. What does this mean for the future of all those protoboard, veroboard, and tagboard designs? It’s not good, but fortunately, there may be an answer. It’s perfboard designed for mounting SOICs, SOTs, and other surface mount devices.

Perfboard is an extremely simple concept. Most through-hole electronic components are built around 0.1″ or 2.54 mm spacing between pins. Yes, there are exceptions, but you can always bend the middle pin of a transistor and put it in a hole. SMT devices are different. You can’t really bend the pins, and the pin pitch is too small for the 0.1″ holes in traditional perfboard.

[electronic_eel] is changing that game up with his own design for perfboard. This perfboard has the traditional 0.1″ holes, but there are SMD pads sprinkled about between these holes. The result is being able to solder SOIC, SOT23-6, SOT23 and SOT363 devices directly to a board alongside 0603 and 0805 devices. Connect everything with a few beads of solder and you have a functional circuit made out of surface mount devices on something that’s still compatible with the old protoboard designs.

This isn’t the first time we’ve seen a new type of protoboard make it into production. A few years ago, Perf+, a bizarre ‘bus-based’ protoboard solution came onto the scene, although that wasn’t really designed for SMD parts. While [electronic_eel] doesn’t have any plans to sell his protoboard, the files are available, and you can easily design your own small piece of perfboard.

Ask Hackaday: The Latest Advances In Perfboard

April 5, 2015 by Brian Benchoff 107 Comments

It’s no secret the Hackaday tip line gets a lot of email from Kickstarter campaigns and PR firms managing Kickstarter campaigns. Most of these are terrible products. Want a five-pound battery that can’t be recharged? Yeah, stuff like that.

Every once in a while, we come across a tip that’s a completely original idea. There’s a balance between ingenuity and practicality with these ideas, and I can’t figure out where this one sits. It’s a Kickstarter for perfboard, yes, but not like any perfboard you’ve ever seen.

Before we dig into this, let’s get some definitions straight. Perfboard is a sheet with holes drilled on a 0.1″ grid. The holes are plated on both sides, and each hole is an individual electrical node. Veroboard, or stripboard is a bunch of holes on a 0.1″ grid. These holes are also plated, but all the holes in a column are a single electrical node. You can cut the tracks between holes, but the basic idea here is to reduce the number of wires needed to connect components. Busboard, seen left, is a continuation of Veroboard, and is laid out like a solderless breadboard.

And so we come to the new invention, Perf+, the perfboard reinvented. This perfboard again is a series of plated holes on a 0.1″ grid. Alongside these holes is a plated bus. This bus does not connect to any hole; instead, a little bit of solder is used to connect it to holes on the same row or column. “Selective Veroboard,” you could call it.

Now for the real trick: on one side of the board, the plated busses run vertically. On the other side of the board, the plated busses run horizontally. This means any two holes on the protoboard can be connected as one electrical node simply with a bit of solder.

If ever there was an idea you could point to and simultaneously say, “that’s clever” and “I have no idea how to use this,” there you go. I’m pretty sure this idea isn’t better than a piece of stripboard, but it is different. If you have any idea of how to used this new, strange, and otherworldly protoboard for something useful, put a note in the comments.