Rebuilding The First Digital Personal Computer

August 16, 2024 by Bryan Cockfield 15 Comments

When thinking of the first PCs, most of us might imagine something like the Apple I or the TRS-80. But even before that, there were a set of computers that often had no keyboard, or recognizable display beyond a few blinking lights. [Artem Kalinchuk] is attempting to recreate one of these very early digital computers, the Kenbak-1, using as many period-correct parts as possible.

Considered by many to be the world’s first personal computer, the Kenbak-1 was an 8-bit machine with 256 bytes of memory, using TTL integrated circuits for the logic as there was no commercially available microprocessor available at the time it was designed. For [Artem]’s build, most of these parts can still be sourced including the 7400-series chips and carbon resistors although the shift registers were a bit of a challenge to find. A custom PCB was built to replicate the original, and with all the parts in order it’s ready to be assembled and put into a case which was built using the drawings for the original unit.

Although [Artem] plans to build a period-correct linear power supply for this computer, right now he’s using a modern switching power supply for testing. The only other major components that are different are the status lamps, in this case switched to LEDs because he wasn’t able to source incandescent bulbs that drew low enough current, and the switches which he’s replaced with MX-style keys. We’ll stay tuned as he builds and tests this over the course of several videos, but in the meantime if you’re curious how this early computer actually worked we featured an emulator for it a while back.

Continue reading “Rebuilding The First Digital Personal Computer” →

FauxTRS Is Definitely Not A Trash 80

July 22, 2024 by Jenny List 12 Comments

Among the 8-bit home micro boom from the late 1970s through early 1980s, the introduction to computing for many wasn’t a pricey Apple or Commodore, instead it was the slightly lower budget machine from Radio Shack. The TRS-80 series of computers live on and have a loyal following among retro computing enthusiasts. But like all such machines the original hardware is harder to find in 2024, so how about the TRS-80 experience without the failing vintage parts? The FauxTRS from [Jpasqua] is just that, the feel of a Model 3 or Model 4, powered by a Raspberry Pi.

In a sense then, this is a very well-designed case for a Raspberry Pi that looks a lot like the Tandy of old. With a modern LCD and keyboard it could just as easily be a normal desktop machine, but when the emulator fires up it does indeed look very much like a small version of the real thing. You can download the STL files from Printables, and for the cost of a few extra parts you can have one too.

Alternatively, if a faux TRS doesn’t do it for you, there’s always the chance of making a more real one.

ESP32 Powers Single-PCB ZX Spectrum Emulator

June 16, 2024 by Tom Nardi 21 Comments

When word first got out that the Chinese board houses were experimenting with full color silkscreens, many in our community thought it would be a boon for PCB art. Others believed it would be akin to cheating by removing the inherent limitations of the medium. That’s not a debate that will be solved today, but here we have an example of a project that’s not only making practical application of the technology, but one that arguably couldn’t exist in its current form without it: a single-PCB ZX Spectrum emulator developed by [atomic14].

There basics here are, well, they’re pretty basic. You’ve got an ESP32-S3, a TFT display, a micro SD slot, and the handful of passives necessary to tie them all together. What makes this project stand out is the keyboard, which has been integrated directly into the PCB thanks to the fourteen pins on the ESP32-S3 that can be used as touch sensor input channels. There are issues with detecting simultaneous keypresses, but overall it seems to work pretty well.

Continue reading “ESP32 Powers Single-PCB ZX Spectrum Emulator” →

An Enigma Machine Built In Meccano

June 15, 2024 by Bryan Cockfield 5 Comments

As far as model construction sets go, LEGO is by far the most popular brand for building not only pre-planned models but whatever the builder can imagine. There are a few others out there though, some with some interesting features. Meccano (or Erector in North America) is a construction set based around parts that are largely metal including its fasteners, which allows for a different approach to building models than other systems including the easy addition of electricity. [Craig], a member of the London Meccano Club, is demonstrating his model Enigma machine using this system for all of its parts and adding some electricity to make the circuitry work as well.

The original Enigma machine was an electronic cypher used by the German military in World War 2 to send coded messages. For the time, its code was extremely hard to break, and led to the British development of the first programmable electronic digital computer to help decipher its coded messages. This model uses Meccano parts instead to recreate the function of the original machine, with a set of keys similar to a typewriter which, when pressed, advance a set of three wheels. The wheels all have wiring in them, and depending on their initial settings will light up a different character on a display.

There are a few modifications made to the design (besides the use of a completely different set of materials) but one of the main ones was eliminating the heavy leaf springs of the original for smaller and easier-to-manage coil springs, which are also part of the electrical system that creates the code. The final product recreates the original exceptionally faithfully, with plans to create a plugboard up next, and you can take a look at the inner workings of a complete original here.

Continue reading “An Enigma Machine Built In Meccano” →

A Cycle-Accurate Sega Genesis With FPGA

August 4, 2023 by Bryan Cockfield 17 Comments

The Field-Programmable Gate Array (FPGA) is a powerful tool that is becoming more common across all kinds of different projects. They are effectively programmable hardware devices, capable of creating specific digital circuits and custom logic for a wide range of applications and can be much more versatile and powerful than a generic microcontroller. While they’re often used for rapid prototyping, they can also recreate specific integrated circuits, and are especially useful for retrocomputing. [nukeykt] has been developing a Sega Genesis clone using them, with some impressive results.

The Sega Genesis (or Mega Drive) was based around the fairly common Motorola 68000 processor, but this wasn’t the only processor in the console. There were a number of coprocessors including a Z80 and several chips from Yamaha to process audio. This project reproduces a number of these chips which are cycle-accurate using Verilog. The chips were recreated using images of de-capped original hardware, and although it doesn’t cover every chip from every version of the Genesis yet, it does have a version of the 68000, a Z80, and the combined Yamaha processor working and capable of playing plenty of games.

The project is still ongoing and eventually hopes to recreate the rest of the chipset using FPGAs. There’s also ongoing testing of the currently working chips, as some of them do still have a few bugs to work out. If you prefer to take a more purist approach to recreating 90s consoles, though, we recently featured a project which reproduced a Genesis development kit using original hardware.

Thanks to [Anonymous] for the tip!

An Open-Source Antikythera Mechanism

July 11, 2023 by Bryan Cockfield 19 Comments

When the Antikythera Mechanism was first discovered, it wasn’t viewed as the wonder that we know it today. Originally the divers who found the device and the first scientists to look at it wrote it off as an astrolabe or other some other common type of clock. It wasn’t until decades later when another set of scientists x-rayed the device and surveyed more of the shipwreck where it was found that it began to become one of the more important archaeological discoveries in history. There have been plenty of attempts to recreate this device, and this replica recreates the mechanisms of the original but is altered so it can be built in a modern workshop.

The build, which took the creators several years of research and development to complete, started off with the known gear schemes found on the original device. However, the group wanted to make it with modern technology including 3D printers and laser cutters, so although they worked from an understanding of the original 2000-year-old device there are some upgrades and changes to accommodate those who want to build this in a modern workshop. Gears made from plastic instead of brass have more friction, which needed to be reduced by building custom bearings machined out of brass. And to complete the machine a number of enclosures of various styles are available to use as well.

Additionally, all of the designs and schematics for this build are open source for anyone to build or modify as they would like, although the group putting this together does plan to sell various parts for this as well. There will be some issues with use, as they point out, since the ancient Greeks didn’t have a full enough understanding of cosmology to get a machine like this to stay accurate for two thousand years, but it’s a fascinating build nonetheless. Reasearchers are still discovering new things about this device too, including the recent find of an earliest possible start date for the machine.

Recreating The ZX Spectrum Unboxing Experience By Manufacturing A New Boxed One

March 26, 2023 by Maya Posch 7 Comments

Why scour the internet for a rare-as-hen’s-teeth new in box ZX Spectrum computer when you can instead order up some parts, assemble a basically all new ZX Spectrum along with the box, instruction manuals and more?

That seems to have been the reasoning behind [Lost Retro Tapes] when they decided to do exactly that. Along with the announcement of the completion on Reddit, the website details the BOM and sourcing the components.

For the mainboard, an existing, redrawn ZX Spectrum 48 Issue 3B PCB was found and ordered from PCBWay. As a UK-based entity, many of the other components were sourced from retro computing shops around the UK, but with all but the LM1889N IC being available for new or with currently produced alternative, it should be viable to source them locally.

Perhaps most impressive was the creation of the box (unfortunately not detailed on the website at this point), and having the manuals (system and BASIC) professionally printed and bound. Along with a few other bits and pieces, including a tape recorder and fresh Horizons tape, the total price tag came to around £412.

Thanks to [Lee Hodgson] for the tip.