Author: Adam Fabio

734 Articles

The Bendix G-15 Runs 75,000 Lines Of Code

December 21, 2024 by 16 Comments

There’s a Blue Bendix in Texas, and thanks to [Usagi Electric] it’s the oldest operating computer in North America.  The Bendix G-15, a vacuum tube computer originally released in 1956, is now booting, and running code from paper tape. [David, aka Usagi] received the G-15 about a year ago from The System Source museum. The goal was to get the computer running so museum patrons could interact with a real tube computer. We’ve been following along since the project began.

[Usagi’s] latest G-15 video covers the last few problems on the road to running code. The biggest hurdle was the fact that the system wasn’t responding properly to the GO button on the typewriter. [Usagi] was able to isolate the issue down to a flip flop and then to a particular signal on an AND gate — the RC signal. The gate appeared to be bad, but swapping the entire circuit card multiple times had no effect. Something else had to be going on.

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ESP32 Hosts A USB Keyboard In This Typewriter

November 17, 2024 by 13 Comments

Did you know the ESP32 can be a USB host? Well it can, and [Volos] uses host mode to build this fun little word processor.

The venerable ESP32 has a well-known USB device mode. Anyone who has programmed one has used it. A bit less known is the microcontroller’s ability to host USB devices. These days, operating as a USB device is relatively simple. But acting as a host is a much more complex task. The ESP32 has a software host that works — but only for Human Interface Devices (HID).  Human interface devices generally are keyboards, mice, trackballs, and similar devices that handle data relatively slowly, forming the interface with us simple humans.

[Volos] uses the EspUsbHost Arduino library for this project. The library makes USB host mode simple to use. Another piece of the puzzle is the LCD board [Volos] picked. It has a dual-role USB Type-C port, meaning the hardware to switch roles is baked in. Other boards may require some modifications or special cables to make things work.

The software is the best part of this build. [Volos] implemented a simple word processor. It can save and load files from a microSD card and, of course, edit text — all controlled by a USB keyboard. He had to use a 4-bit palette to save memory. This gives the device a retro charm that reminds us of Don Lancaster’s TV Typewriter. The source for this and all of [Volos] projects can be found on GitHub. Now, all we need is a spell check that can fit in the memory constraints of the ESP32! We have to admit the chip has a lot of potential USB tricks.

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The Greengate DS:3 Part 2: Putting A Retro Sampler To Use

October 14, 2024 by 2 Comments

The Greengate DS:3 had been re-created in the form of the Goodgreat. Now [Bea Thurman] had to put it to use. If the Greengate DS:3 card was rare,  the keyboard was nearly impossible to find. After a long search, [Bea] bought one all the way from Iceland.  The card of course came courtesy of [Eric]. 

It was time to connect the two together.  But there was a problem — a big problem. The GreenGate has a DB-25 connected via a ribbon cable to the board’s 2×10 connector. The keyboard that shipped with those cards would plug right in.  Unfortunately, [Bea’s] keyboard had a DIP-40 IDC connector crimped on its ribbon cable.  What’s more the connectors for the sustain and volume pedals were marked, but never drilled out. The GreenGate silk screen was still there though. 

Maybe it was a prototype or some sort of modified hardware. Either way, the 40-pin DIP connector had to go if the keyboard ever were to work with the card. What followed were a few hours of careful wire tracing 

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Solving A Retrocomputing Mystery With An Album Cover: Greengate DS:3

October 14, 2024 by 10 Comments

[Bea Thurman] had a retro music conundrum. She loved the classic Greengate DS:3 sampler, but couldn’t buy one, and couldn’t find enough information to build her own. [Bea’s] plea for help caught the attention of [Eric Schlaepfer], aka  [TubeTime]. The collaboration that followed ultimately solved a decades-old mystery. 

In the 1980s, there were two types of musicians: Those who could afford a Fairlight CMI and everyone else. If you were an Apple II owner, the solution was a Greengate DS:3. The DS:3 was a music keyboard and a sampler card for the Apple II+ (or better). The plug-in card was a bit mysterious, though. The cards were not very well documented, and only a few survive today. To make matters worse, some chips had part numbers sanded off. It was a bit of a mystery until [Bea and Tubetime] got involved. 

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The Hidden Crystal Method

September 8, 2024 by 25 Comments

Ever been working on a project and get stuck on one of those last little details?  That’s what happened to [Empire of Scrap].  He’s building an Ohio Scientific (OSI) superboard II replica. He wants it to be accurate down to the dates on the chips. It is quite an impressive build.  The problem is the crystal. OSI used large crystals, even by early 1980s standards. The crystal is in a large can with thick pins, like something you’d expect to find in old radio equipment. The problem is that this crystal package isn’t made anymore. 

The crystal had to be exactly 3.932160 MHz, and while [Empire] has a huge collection of vintage crystals, he didn’t have the right one from the 70s. He did, however, have that value in a modern crystal.  

The solution? Hide the new crystal in the can of an older one. The only problem is that crystals are sealed. The bottom appeared to be some sort of plastic or resin.  Gong after it with a side cutter, [Empire] realized it was glass!  Thankfully, none of it got in his eyes, though his hands may have taken a bit of a beating. 

With the old crystal’s shell hollowed out, [Empire] installed the modern device and potted everything in resin. The transplant worked. Now, all that’s left is to fire up the OSI and start hacking. 

Want to build a replica computer but don’t want to hunt down the parts? Check out [Taylor] and [Amy’s] build of this minipet. Regardless of the size of the case, crystals all work in the same way.

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Moonbounce Music

August 11, 2024 by 7 Comments

There’s something inspiring about echos. Who among us hasn’t called out or clapped hands in a large space just to hear the sound reflected back? Radio takes this to a whole new level. You can bounce signals from buildings, aircraft, the ionisphere, or even the Moon itself. Humans have been bouncing radio waves from the moon for decades. It’s been used at war, and in peacetime. But [Hainbach] might be the first to use it for music.

Earth Moon Earth or EME communication is quite popular with amateur radio operators. With the right equipment, you can bounce a signal off the moon and hear the echo around 2.5 seconds later. The echo isn’t quite normal though. The moon and the earth are both rotating and moving in relation to each other. This causes Doppler shifts. At higher frequencies, even the craters and surface features of the moon can be heard in the echo.

[Hainbach] spent some time learning about moonbounce at a large radio telescope, and wanted to share this strange audio effect with the world. Unfortunately, most of us don’t have the large microwave dish required for this. The next best thing was to create an application which emulates the sound of a moon bounce. To this end, [Hainbach] created a Moon Echo, an audio plugin that emulates a moonbounce.

Moon Echo was created using sounds from a soprano signer and a double bass. [Hainbach] had to be careful not to be too musical, as ham operators are not allowed to broadcast music. This meant all the tests had to be broken into short non-musical clips. Rolling all this empirical data into a model took quite a bit of work, but the end result is worth it.

If you’d like to learn how to moonbounce yourself, check this article out.
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Be Your Own DJ With QN8066 And An Arduino Library

August 10, 2024 by 5 Comments

The QN8066 is a fun little FM transmitter chip. It covers the full FM broadcast band and has built-in DSP. You would find this sort of part in car cell phone adapters before every vehicle included Bluetooth or an AUX port.  [Ricardo] has created an Arduino library to bring the QN8066 to the masses.

The chip is rather easy to use – control is handled with a common I2C interface. All the complex parts – Phase Locked Loop (PLL), RF front end, power management, and audio processing are all hidden inside. [Ricardo’s] library makes it even easier to use. One of the awesome features of the 8066 is the fact that it handles Radio Data System (RDS). RDS is the subcarrier datastream that allows FM stations to inject information like song title and artist into the signal. The data is then displayed on your radio screen.

You can find the source to [Ricardo’s] library on GitHub. Using it is as simple as picking it up from the Arduino IDE.

If you are looking for an RDS-enabled radio to test out your QN8066 design, you wouldn’t do too bad with this Gameboy cartridge receiver.

Click through the break for a video from [Ricardo] explaining his QN8066 design. Continue reading “Be Your Own DJ With QN8066 And An Arduino Library” →