A Modem As A Cassette Interface

January 24, 2025 by Jenny List 20 Comments

At least some in the audience will at some time in the distant past have loaded or saved a program on cassette, with an 8-bit home computer. The machine would encode binary as a series of tones which could be recorded to the tape and then later retrieved. If you consider the last sentence you’ll quickly realize that it’s not too far away from what a modem does, so can a modem record to cassette and decode it back afterwards? [Jesse T] set out to give it a try, and as it turns out, yes you can.

The modem talks and listens to the cassette recorder via circuitry that provides some signal conditioning and amplification, as well as making a dial tone such that the modem thinks it’s talking to a real phone line. An Arduino steps in as dial tone creator.

Of course, this is hardly a viable solution to 21st century data storage need, but that’s hardly the point as it’s a cool hack. We like it, and oddly we’ve seen a similar technique used with a retrocomputer in the past.

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Cassette Tape Plays MP3s

January 6, 2025 by Bryan Cockfield 66 Comments

Cassette tapes were a major way of listening to (and recording) music througout the 1980s and 1990s and were in every hi-fi stereo, boom box, and passenger vehicle of the era. Their decline was largely as a result of improvements in CD technology and the rise of the MP3 player, and as a result we live in a world largely absent of this once-ubiquitous technology. There are still a few places where these devices crop up, and thanks to some modern technology their capabilities as a music playback device can be greatly enhanced.

The build starts, as one might expect, by disassembling the cassette and removing the magnetic tape from the plastic casing. With the interior of the cassette empty it’s capable of holding a small battery, USB-C battery charger, and a Bluetooth module. The head of an old tape deck can be wired to the audio output of the Bluetooth module and then put back in place in the housing in place of the old tape. With the cassette casing reassembled, there’s nothing left to do but pair it to a smartphone or other music-playing device and push play on the nearest tape deck.

As smartphones continue to lose their 3.5 mm headphone jacks, builds like this can keep lots of older stereos relevant and usable again, including for those of us still driving older vehicles that have functioning tape decks. Of course, if you’re driving a classic antique auto with a tape technology even older than the compact cassette, there are still a few Bluetooth-enabled options for you as well.

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It’s Spreadsheets All The Way Down For This 80s Handheld

September 5, 2024 by Bryan Cockfield 9 Comments

Unlike the today’s consumer computer market, the 1980s were the wild west in comparison. There were all kinds of different, incompatible operating systems, hardware, and programs, all competing against one another, and with essentially no networking to tie everything together. Some of these products were incredibly niche as well, only running one program or having a limited use case to keep costs down. Such was the Convergent WorkSlate, a computer that ran only a spreadsheet with any programs also needing to be built into a spreadsheet.

Upon booting the device, the user is presented with a fairly recognizable blank spreadsheet, albeit with a now-dated LCD display (lacking a backlight) and a bespoke keyboard and cursor that wouldn’t have allowed for easy touch typing. The spreadsheet itself is quite usable though, complete with formatting tools and the capability to use formulas like a modern spreadsheet program would. It also hosted a tape deck for audio and data storage, a modem for communicating with other devices, and an optional plotter-style printer. The modem port is how [Old VCR] eventually interfaces with the machine, although as one can imagine is quite a task for a piece of small-batch technology from the 80s like this. After learning how to send and receive information, a small game is programmed into the machine and then a Gopher interface is built to give the device limited Internet connectivity.

The investigation that [Old VCR] goes into on this project to get this obsolete yet unique piece of hardware running and programmed to do other tasks is impressive, and worth taking a look at especially because spreadsheets like this aren’t Turing-complete, leading to a few interesting phenomenon that most of us wouldn’t come across in the modern computing world. Since only around 60,000 units were ever made it’s difficult to come across these machines, but if you want to take a look at the spreadsheet world of the 80s without original hardware you can still run Lotus 1-2-3 natively in Linux today.

Thanks to [Cameron] for the tip!

A Non-Musical Use Case For 8-Track

August 28, 2024 by Bryan Cockfield 23 Comments

There was a time in the not-too-distant past when magnetic tape was the primary way of listening to and recording audio. Most of us are familiar with the cassette tape, a four-track system that plays first one side of the tape, then the other. There was the eight-track tape as well which did not have quite as much popularity or longevity but did have a few interesting features that [Serial Hobbyism] took advantage of to make an interactive game.

The defining feature of the eight-track system, beyond the obvious eight tracks on the tape, is that the tape runs in a continuous loop, never needing to be stopped or flipped over. Instead, four buttons select pairs of the eight tracks, moving a head immediately to make the switch on-the-fly. [Serial Hobbyism]’s game plays a trivia-style audio recording and asks the player to answer questions by pushing one of the four “program” buttons to switch tracks. If the correct track is selected, the recorded audio congratulates the player and then continues on with the game. Likewise, if an incorrect track is selected, the recording notes that and the game continues.

Another interesting feature of this game is that it can be played without modifying an eight-track player, as the selectable tracks are a core function of this technology. They can be used in a similar way as cassette tapes to store computer data and a data recorder similar to the eight-track system was used on the Voyager space probes, although these only bear a passing resemblance.

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Happy Birthday To Dad, Retrocomputer Style

August 22, 2024 by Dan Maloney 3 Comments

For those of us who lived through the early 8-bit computing revolution — the tail end, in our case — it’s hard to believe that there’s a second wave of retrocomputing nostalgia underway. But as this bit-banged TRS-80 birthday bonus pack shows, the first generation did a pretty good job passing the retro torch.

With his father’s 70th birthday coming up and full of “borrowed nostalgia” for the good old days, [Josh Sucher] scored a TRS-80 off eBay and experimented with what could be possible. After 50-odd years, the machine needed a bit of TLC, including a new power supply, some keyboard repairs, and the usual recapping. He also had to soup the machine up a bit, given that its original capabilities were so limited.

Chief among these mods was a rudimentary IP stack thanks to a TRS-IO card, which emulates a lot of functionality of the original TRS-80 Expansion Module and adds an ESP-32 for WiFi capability. This allowed [Josh] to get a neat “Dadbot” chatbot going on the machine, using years of his dad’s text messages to train the model. There’s also a game of Go, an RPG based on his parents’ lives, and a local news and weather app. Most impressive, though, is the bit-banged audio app that uses the TRS-80’s cassette interface to play a passable rendition of “Happy Birthday to You.” The video below has the full demo.

It’s clear that this lengthy project was a labor of love, and we approve of the results. It’s been a long, long time since we first caught wind of the TRS-80 through the Radio Shack catalog, and projects like this make us feel like scratching up one for ourselves to play with.

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Building A Cassette Deck Controller To Save A Locked Out Car Stereo

July 9, 2024 by Zoe Skyforest 27 Comments

Cars have had DRM-like measures for longer than you might think. Go back to the 1990s, and coded cassette decks were a common way to stop thieves being able to use stolen stereos. Sadly, they became useless if you ever lost the code. [Simon] had found a deck in great condition that was locked out, so he set about building his own controller for it.

The build relies on the cassette transport of a car stereo and a VFD display, but everything else was laced together by Simon. It’s a play-only setup, with no record, seeing as its based on an automotive unit. [Simon]’s write up explains how he reverse engineered the transport, figuring out how the motors and position sensors worked to control the playback of a cassette.

[Simon] used an Atmega microcontroller as the brains of the operation, which reads the buttons of the original deck via an ADC pin to save I/O for other tasks. The chip also drives the VFD display for user feedback, and handles auto reverse too. The latter is thanks to the transport’s inbuilt light barriers, which detect the tape’s current status. On the audio side, [Simon] whipped up his own head amplifier to process the signal from the tape head itself.

Fundamentally, it’s a basic build, but it does work. We’ve seen other DIY tape decks before, too. There’s something about this format that simply refuses to die. The fans just won’t let Compact Cassette go down without a fight. Video after the break.

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Here’s The Norwegian Tape Deck Teardown You’ve Been Waiting For

May 15, 2024 by Zoe Skyforest 37 Comments

“They just don’t build ’em like they used to” is a truer statement every year. Whether your vice is CRTs, film cameras, or tape decks, you’ll know that the very best gear simply isn’t manufactured anymore. Even the day-to-day stuff from 60 years ago is often a cut above a lot of today’s equipment. [Anthony Kouttron] shows us this with his teardown of a Tandberg TCD301 from many decades ago.

The Tandberg unit is beautifully finished in wood and metal, a style of construction that’s fairly rare these days. It’s got big, chunky controls, and a certain level of heft that is out of vogue in modern electronics. Heavy used to mean good — these days, it means old. That’s not to say it’s indestructible, though. It’s full of lots of old plastic pulleys and fasteners that have aged over the decades, so it’s a little fragile inside.

Still, [Anthony] gives us a great look at the aluminium chassis and buttons and the electromechanical parts inside. It’s a rats-nest design with lots of discrete components and wires flying between boards. You couldn’t economically produce this and sell it to anyone today, but this is how it was done so many years ago.

This non-functional unit ended up being little more than a salvage job, but we’re still glad that [Anthony] gave us a look inside. Still, if you long for more cassette-themed teardowns, we’ve got the goodness you’re looking for!