classic hacks

2644 Articles

Breadboard Colecovision

March 7, 2016 by 13 Comments

The Colecovision was a state-of-the-art game console back in 1983. Based around the Z-80, it was almost a personal computer (and, with the Adam add-on, it could serve that function, complete with a daisy wheel printer for output). [Kernelcrash] set out to recreate the Colecovision on a breadboard and kept notes of the process.

His earlier project was building a Funvision (a rebranded VTech Creativision) on a breadboard, so he started with the parts he had from that project. He did make some design changes (for example, generating separate clocks instead of using the original design’s method for producing the different frequencies needed).

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An Internet Radio In A Classic Cathedral Case

February 27, 2016 by 13 Comments

If you’re looking for a hot collectible item and a great restoration project, cathedral-style radios from the 1930s are a solid choice. But they’re getting harder to find as the years roll by, so if your heart’s content is to listen to modern broadcasts through a radio with a classic look, you may need to roll your own cathedral case for an internet radio.

The cathedral-style case was a hugely successful form-factor for radios back in the day, with variations on the arch-top theme ranging from Gothic to Art Deco. For this build, [nick.r.brewer] decided on a more parabolic arch. His build log has SVG files for the individual ribs that were cut from plywood with an X-Carve. A Raspberry Pi and TFT display were mounted inside the finished case, along with a Bluetooth module and a 20W amplifier and speaker. A big 3-pole rotary switch with custom knob selects the audio source and evokes that 1930s feel. It ended up looking pretty good, and the video after the break shows that it sounds nice, too.

We featured a fair number of internet-radio-in-a-classic-case builds before, but we’re surprised to see no cathedral-style radios have been modded. Maybe it’s time to hit the flea market and estate sales and see what turns up.

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Upgrading And Desoldering A Fake CPU

February 24, 2016 by 54 Comments

[quarterturn] had an old Apple Powerbook 520c sitting around in his junk bin. For the time, it was a great computer but in a more modern light, it could use an upgrade. It can’t run BSD, either: you need an FPU for that, and the 520 used the low-cost, FPU-less version of the 68040 as its main processor. You can buy versions of the 68040 with FPUs direct from China, which means turning this old Powerbook into a BSD powerhouse is just a matter of desoldering and upgrading the CPU. That’s exactly what [quarterturn] did, with an unexpected but not surprising setback.

The motherboard for the Powerbook 500 series was cleverly designed, with daughter cards for the CPU itself and RAM upgrades. After pulling the CPU daughter card from his laptop, [quarterturn] faced his nemesis: a 180-pin QFP 68LC040. Removing the CPU was handled relatively easily by liberal application of ChipQuik. A few quick hits with solder braid and some flux cleaned everything up, and the daughter card was ready for a new CPU.

The new FPU-equipped CPU arrived from China, and after some very careful inspection, soldering, and testing, [quarterturn] had a new CPU for his Powerbook. Once the Powerbook was back up and running, there was a slight problem. The chip was fake. Even though the new CPU was labeled as a 68040, it didn’t have an FPU. People will counterfeit anything, including processors from the early 90s. This means no FPU, no BSD, and [quarterturn] is effectively back to square one.

That doesn’t mean this exercise was a complete loss. [quarterturn] did learn a few things from this experience. You can, in fact, desolder a dense QFP with ChipQuik, and you can solder the same chip with a regular soldering iron. Networking across 20 years of the Macintosh operating system is a mess, and caveat emptor doesn’t translate into Mandarin.

Breathing New Life Into An Old Key

February 21, 2016 by 13 Comments

For most of us who have experimented with Morse code, the oldest key we are likely to have used will have been a piece of military surplus kit from the Second World War era. [Kyle Gabriel] however is a lucky man. His grandfather left him his key-on-board telegraph practice set, a vintage key and telegraph sounder arrangement used to learn Morse code in the days when the telegraph was king. Rather than keep the set merely as an heirloom, [Kyle] set about bringing it up to date by interfacing it to a Raspberry Pi and writing a Morse reader program.

Along the way [Kyle] had to contend with debouncing the switching signal from the key, considering an RC network before settling on a software debounce timer. He provides a brief synopsis of the mechanics of Morse decoding software, and a demonstration of the code in action which you can see in the video below the break.

[Kyle’s] decoding software, beatbybeat, is on GitHub. We can see it will be a useful tool for anyone interested in Morse, or who is writing their own Morse software.

Morse code has featured on these pages more than a few times over the years. Of relevance to this piece are an Arduino decoding Morse code, a more up-to-date practice oscillator with a home-made key, and a couple of other vintage telegraphs reading RSS feeds and reading emails.

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Sony VTR with replacement foam brushes

Resurrecting A 1960’s VTR With Foam

February 18, 2016 by 12 Comments

Nearly fifty years back, Sony launched the DVC-2400, their first consumer grade video camera. This unit weighed in at 10 pounds, and recorded only 20 minutes of footage per reel. It left something to be desired for $1250, or nearly $9000 in today’s dollars.

[NeXT] got his hands on one of these camera kits, and began bringing it back to life. While all the pieces were included, the Video Tape Recorder (VTR), which is used to play back the footage, didn’t power up. A little poking found a dead transistor. After determining a modern replacement part, the voltages checked out. However, the drum still wasn’t spinning.

Further disassembly found that the drum’s DC motor was made on the cheap, using a foam instead of springs to apply pressure on the brushes. This foam had worn out and lost its springy qualities, so no electrical contact was made. New foam was cut out as a replacement. Once reassembled, the drum spun successfully. After some adjustment, the VTR was running at the correct speed once again.

With this working, the VTR should be ready to go. However, camera still isn’t working, so we’re awaiting a part 2.

The Voice Recognition Typewriter

February 17, 2016 by 29 Comments

Typewriters with voice recognition have existed for over one hundred years; they were called secretaries. Robots are taking all the jobs now, and finally dictation and typing is a job that can be handled by a computer. [Zip Zaps] used an old Smith Corona typewriter to automate the process of turning dictation into print. Like a secretary hunched over an anachronistic IBM Selectric in the first season of Mad Men, this robot will take dictation and accept the overt sexism of a 1960s Manhattan ad agency.

Instead of the machinations of a few biological actuators, this typewriter is controlled with an array of servos driven by Pololu Maestro servo controller. There are twelve servos that move a small actuator down onto the keys, and another twelve servos that move the others above the correct row of the keyboard. The carriage return lever is actuated by a stepper motor, linear rail, and giant plastic lever.

While a robot that can use a typewriter is impressive, the real trick is getting it to take dictation. [Zip Zaps] used the built-in voice recognition found in Windows for this, streaming characters over a serial port to the Arduino-based electronics.

Does it work? Yes, surprisingly it does. Is it useful? Well, typewriters naturally have a cleaner, more analog tone about them, and you can’t replicate the typing experience of an old Smith Corona typewriter with a digital format. This build is just the natural extension of what digital electronics are capable of these days, and we look forward to seeing someone with this amazing device in our local Starbucks.

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Deaccelerating The Apple IIc Plus

February 13, 2016 by 40 Comments

The Apple IIc Plus is arguably – very arguably from my experience – the best Apple II computer ever made. It’s portable, faster than the IIe, had a much higher capacity built-in drive, and since the Plus could run at 4MHz, it was faster than the strange eight or sixteen bit Apple IIGS. Recently, [Quinn] has been fascinated with the IIc Plus, and has gone so far as to build a custom gamepad and turn the IIc Plus into a laptop. Now, she’s turned her attention to the few things Apple got wrong with the Apple IIc Plus – the startup beep and defaulting to 4MHz on every boot instead of Apple II’s standard 1MHz that’s used in the Apple II, II Plus, IIe, and IIc non-Plus.

The original Apple II is surprisingly primitive. Apart from writing a loop of NOPs and counting cycles, there’s no way to keep time. There is no clock, no timer, no tick counters, and no interrupts. If you’re writing a game for the Apple II that depends on precise timing, the best you’ll be able to manage is a delay loop. This worked for a time, until the Apple IIc Plus was released with a default clock of 4MHz. It was a great idea for AppleWorks and other productivity apps, but [Quinn] is doing retrocomputing, and that means games. Booting the Apple IIc Plus into its 1MHz mode means turning it on and holding escape while resetting the computer every time. It’s very annoying, but a mod to make the IIc Plus run at 1MHz by default would turn her into one of the most accomplished currently active Apple II developers.

The process of booting into the IIc Plus’ 1MHz mode requires holding down escape while restarting the computer. This should tell you something: it’s not a hardware switch that changes speed. It’s in the ROM, and that means diving into the Technical Reference Manual, looking at the listings in the ROM monitor, and figuring out how everything works.

The IIc Plus ROM is incredibly complex – it’s 32k of hand assembled code with jump tables bouncing everywhere. After a ton of research, [Quinn] successfully reverse engineered the ‘slow down if the ESC key is pressed’ routine, allowing her to boot the machine at 1MHz by default, and 4MHz if there’s a soft reset with the option key pressed. Everything works great, and [Quinn] has the video to prove it

This isn’t [Quinn]’s first attempt at hacking the lowest levels of the Apple IIc Plus ROM. Because the IIc Plus ran at 4MHz by default, the startup beep was so very wrong. She fixed that, and with two very useful patches under her belt, she burned a few new chips with her ROM patches. In total, there’s only a few dozen bytes of hers in the new 32k ROM, but that’s enough to make her one of the top current firmware developers for the Apple II platform.