classic hacks

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An 8-Bit ALU, Entirely From NAND Gates

March 31, 2018 by 18 Comments

One of the things that every student of digital electronics learns, is that every single logic function can be made from a combination of NAND gates. But nobody is foolhardy enough to give it a try, after all that would require a truly huge number of gates!

Someone evidently forgot to tell [Notbookies], for he has made a complete 8-bit ALU using only 4011B quad NAND gates on a set of breadboards, and in doing so has created a minor masterpiece with his wiring. It’s inspired by a series of videos from [Ben Eater] describing the construction of a computer with the so-called SAP (Simple As Possible) architecture. The 48 4011B DIP packages sit upon 8 standard breadboards, with an extra one for a set of DIP switches and LEDs, and a set of power busbar breadboards up their sides. He leaves us with the advice borne of bitter experience: “Unless your goal is building a NAND-only computer, pick the best IC for the job“.

We have covered countless processors and processor components manufactured from discrete logic chips over the years, though this makes them no less impressive a feat. The NedoNAND has been a recent example, a modular PCB-based design. TTL and CMOS logic chips made their debut over 50 years ago so you might expect there to be nothing new from that direction, however we expect this to be  well of projects that will keep flowing for may years more.

Via /r/electronics/.

Build Your Own Antenna For Outdoor Monitoring With LoRa

March 31, 2018 by 15 Comments

LoRa and LPWANs (Low Power Wide Area Networks) are all the range (tee-hee!) in wireless these days. LoRa is a sub 1-GHz wireless technology using sophisticated signal processing and modulation techniques to achieve long-range communications.

With that simplified introduction, [Omkar Joglekar] designed his own LoRa node used for outdoor sensor monitoring based on the HopeRF RFM95 LoRa module. It’s housed in an IP68 weatherproof enclosure and features an antenna that was built from scratch using repurposed copper rods. He wrote up the complete build, materials, and description which makes it possible for others to try their hand at putting together their own complete LoRa node for outdoor monitoring applications.

Once it’s built, you can use this simple method to range test your nodes and if you get really good, you might be setting distance records like this.

This Is How The Fonz Would Play MP3s

March 30, 2018 by 10 Comments

Here at Hackaday, we love to see old hardware treated with respect. A lovingly restored radio or TV that’s part of our electronic heritage is a joy to behold, and while we understand the desire to stream media from a funky retro case, it really grates when someone throws away the original guts to make room for new electronics.

Luckily, this Seeburg jukebox wall remote repurposing is not one of those projects. [Scott M. Baker] seems to have an appreciation for the finer things, and when he scored this classic piece of Mid-Century Americana, he knew just what to do. These remotes were situated around diners and other hangouts in the 50s and 60s and allowed patrons to cue up some music without ever leaving their seats. They were real money makers back in the day, and companies put a lot of effort into making them robust and reliable.

[Scott]’s first video below shows the teardown of this unit; you can practically smell the old transformer and motor windings. His goal in the second video was to use the remote to control his Raspberry Pi jukebox; he wisely decided to leave everything intact and use the original electromechanically generated pulses to make selections. His analysis led to a nicely executed shield for his Pi which conditions the pulses and imitates coin drops; happily, the coin mechanism still works too, so you can still drop a quarter for a tune.

The remote is working well now, but [Scott] still needs to finish up a few odds and ends to bring this one home. But we love the look and the respect for tradition here, as we did when this juke got a Raspberry Pi upgrade to imitate a missing wall remote.

Continue reading “This Is How The Fonz Would Play MP3s” →

Eavesdropping On A VGA Monitor’s Conversations

March 29, 2018 by 28 Comments

Did you ever wonder what your monitor and your computer are talking about behind your back? As it turns out, there’s quite a conversation going on while the monitor and the computer decide how to get along, and sniffing out VGA communications can reveal some pretty fascinating stuff about the I²C protocol.

To reverse engineer the configuration information exchanged between a VGA monitor and a video card, [Ken Shirriff] began by lopping a VGA cable in two. The inside of such cables is surprisingly complex, with separate shielding wires for each color and sync channel and a host of control wires, all bundled in multiple layers of shielding foil and braid to reduce EMI. [Ken] identified the clock and data lines used for the I²C interface and broke those out into a PocketBeagle for analysis using the tiny Linux machine’s I²C tools.

With a Python script to help decode the monitor’s Extended Display Identification Data (EDID) data, [Ken] was able to see everything the monitor knows about itself — manufacturer, serial number, all the supported resolution modes, and even deprecated timing and signal information left over from the days when CRTs ruled the desktop. Particularly interesting are the surprisingly limited capabilities of a VGA display in terms of color reproduction, as well as [Ken]’s detailed discussion on the I²C bus in general and how it works.

We always enjoy these looks under the hood that [Ken] is so good at, and we look forward to his reverse engineering write-ups. His recent efforts include a look at core memory from a 50-year old mainframe and reverse engineering at the silicon level.

Emulating A Complete Commodore 64

March 28, 2018 by 40 Comments

When the Commodore 64 was released in 1982, it was a masterpiece of engineering. It had capabilities far outstripping other home computers, and that was all due to two fancy chips inside the C64. The VIC-II, the video chip for the C64, had sprites and scrolling, all stuffed into a single bit of silicon. The SID chip was a complete synthesizer on a chip. These bits of silicon made the C64 the best selling computer of all time, but have also stymied efforts to emulate a complete C64 system on a microcontroller.

[Frank Bösing] has just managed to emulate an entire C64 on a Teensy 3.6. The Teensy uses an exceptionally powerful microcontroller, but this is a labor of love and code.

The inspiration for this project comes from a reverse-engineered SID chip that was ported to the Teensy 3.2. The SID chip is the make it or break it feature of any C64 emulation, but the Teensy 3.2 didn’t have enough RAM for the most recent versions of reSID. With the release of the Teensy 3.6, [Frank] figured the increased amount of RAM would allow a complete C64 system, so he built it.

The new C64 emulator uses a Teensy 3.6, with a small add-on ‘shield’ (or whetever we’re calling them) to provide connectors for joysticks and the Commodore IEC bus. There’s audio out, support for USB keyboards, and support for an IL9341 SPI display or a regular ‘ol VGA display.

The entire development of this Commodore emulator has been documented over on the PJRC forums, and all the code is over on GitHub. It’s a fantastic piece of work, and as the video (below) shows, this is a real Commodore 64 that fits in your pocket.

Continue reading “Emulating A Complete Commodore 64” →

An Amiga 500 For The 21st Century

March 25, 2018 by 26 Comments

There was a period in the late 1980s when the home computer to own did not come with an Apple logo and was not an IBM, Compaq, or any of the other clones, but instead sported a Commodore logo. The Amiga 500 was an all-in-one console-style cased machine that maybe wasn’t quite the computing powerhouse you might have wished it to be, but gave you enough of the capabilities of the more accomplished 16-bit machines of the day to be an object of desire while also having a games catalogue second to none.

A500s have survived in reasonable numbers, but inevitably working A500s haven’t. Fortunately there are decent emulators, and it was for one of these that [intric8] has produced an extremely well-done installation of a Raspberry Pi 3 in an Amiga case. The intention has been throughout to avoid modification or damage to the Amiga case, and eventually to have all Amiga internal peripherals including the floppy drive in a fully working condition.

The result has a Tynemouth Software USB adaptor for the Amiga keyboard, and a set of nicely designed 3D printed backplates to bring the extended Raspberry Pi ports to the back of the case. The floppy isn’t yet interfaced and there isn’t a socket for the quadrature mouse, but otherwise it’s a very tidy build. He might be interested in one of the several USB to quadrature interfaces we’ve featured over the years.

You might ask why so much effort should be put in for an emulation of an A500, and in a sense you’d be right to do so. The Pi will run the emulator from any case or none. But if you happen to have a spare A500 case, why not give this one a go!

Converting Power Supplies For Antique Computers

March 22, 2018 by 16 Comments

Just because something is “never used” doesn’t mean it’s good. [Inkoo Vintage Computing] learned that lesson while trying to repair an Amiga 500 and finding parts online that were claimed to be “new” in that they were old stock that had never been used. The problem was that in the last 30 years the capacitors had dried out, rendering these parts essentially worthless. The solution, though, was to adapt a modern PSU for use on the old equipment.

The first hurdle to getting this machine running again was finding the connector for the power supply. The parts seemed to have vanished, with some people making their own from scratch. But after considering the problem for a minute longer they realized that another Commodore machine used the same parts, and were able to source a proper cable.

Many more parts had to be sourced to get the power supply operational, but these were not as hard to come across. After some dedicated work with the soldering iron, the power supply was put to use running the old Amiga. Asture readers will know that [Inkoo Vintage Computing] aren’t strangers to the Amiga. They recently were featured with a nondestructive memory module hack that suffered from the same parts sourcing issues that this modification had, but also came out wonderfully in the end.