RetroPie Turned Game Gear

Running vintage console emulators on a Raspberry Pi seems to be the thing all the cool kids are doing. The coolest RetroPie builds take a vintage console – usually of the Nintendo genus – stuff a Raspi in there somehow, and Bob’s your uncle. [Phil Herlihy] over at Adafruit is throwing his hat into the ring with a similar build. For this one, though, he’s using Sega’s oft-maligned Game Gear. He might actually get more than a few hours out of the battery with this one, and the battery is rechargeable, too. You can’t beat that.

The build begins with tearing down an old Game Gear, chopping up the PCB to save the button contact, and starting to fit all the components in there. The display is completely replaced with a 3.5″ composite display, a bit larger than the 3.2″ display found in a stock Game Gear. That’s not a problem, there’s a surprising amount of space behind the bezel, and if you’re good enough with an xacto blade and a file, it will look stock.

The rest of the components include an amplifier board, battery charge regulator, a 2500mAh LiPo, and a Teensy to read the buttons. There are a few modifications required for the Pi, but the finished device presents a USB port to the outside world; keep a keyboard by your side, and this is a portable Pi in every respect.

Building an Industrial Control Unit With an Industrial Control Unit

Back in the 70s, industrial control was done with either relays and ladder logic or new programmable logic controllers. These devices turned switches on and off, moved stuff around a factory, and kept the entire operation running smoothly. In the late 70s, Motorola came out with an Industrial Control Unit stuffed into a tiny chip. The chip – the MC14500 – fascinated [Nicola]. He finally got around to building an ICU out of this chip, and although this was the standard way of doing things 30 years ago, it’s still an interesting build.

[Nicola]’s ICU is extremely simple, just eight relays, eight inputs, the MC14500, a clock, and some ROM. After wiring up the circuit, [Nicola] wrote a compiler, although this chip is so simple manually writing opcodes to a ROM wouldn’t be out of the question.

To demonstrate his ICU, [Nicola] connected up an on/off switch, a start button, and a stop button. The outputs are a yellow, green, and red lamp. It’s a simple task for even a relay-based control scheme, but [Nicola]’s board does everything without a hitch.

If you’re looking for something a little more complex, we saw the MC14500 being used as an almost-CPU last year.

Video below.

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Diode Steering and Counting With A 555

While you’re not likely to see this technique used very much today, there’s a lot you can do with a 555, some logic chips, and a handful of diodes. [Fran] is here with a great example of using these simple parts to build a circuit that counts to zero, using parts you can probably find under your workbench.

[Fran] was inspired to build this diode counter from one of [Dave]’s Mailbags and [Colin Mitchell]’s 555 circuit book. The 555 is the standard component found in every parts drawer, but since we have tiny microcontrollers that cost the same as a 555, we’re not seeing the artistry of a simple timer chip and a few logic chips much these days.

This circuit began with a 555 attached to a 4017B decade counter. Simply by tying a few LEDs to the output of the 4017, [Fran] made a bunch of LEDs light up in sequence. Cool, but nothing unexpected. The real trick uses a few diodes and six LEDs to build a scanner – a line of LEDs that will blink from left to right, then right to left. Impressive, and with a little more circuitry it’s a Larson Scanner, as seen in Battlestar Galactica and Knight Rider.

The real trick for this technique comes when [Fran] pulls out a piece of protoboard, several dozen diodes, and seven old transistors to have a seven-segment display count from zero to nine. The 4017 simply counts out on ten pins, and each of these pins is wired to a bunch of diodes for each segment in the display. Add in a few resistors and a transistor, and [Fran] replicated what’s inside a seven-segment driver with discrete parts.

If counting to zero isn’t enough proof that you can do a whole lot with some diodes and logic chips, how about programming an Atari 2600 with one?

Video below.

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A Smaller, Homebrew Amstrad

Although they weren’t very popular in America, the Amstrad CPC 464 and CPC 6128 were extremely well-received in Europe. [Zaxon] loved his ‘464, and for a bit of a learning experience – and the fact that an Amstrad takes up an exceptional amount of desk space – decided to make a clone of his favorite computer (.pl, Google translatrix).

The clone began as a simple schematic of the original Amstrad CPC 464, but the parts used in the original required some modern equivalents. Still, most of the old chips remained in the clone; the original Hitachi HD46505 CRT controller remains, as do the original DRAM chips and the vintage Z80 CPU.

A few modern amenities were added, including an interface for a PS/2 keyboard and a disk that’s much improved over the original cassette drive or weird 3.5″ disks: a Disk On Module, or basically a CompactFlash card in a strange form factor that plugs straight into a motherboard’s IDE socket. They’re mostly seen when tearing apart old thin clients, but using them in retrocomputing project is a great idea.

Thanks [rasz_pl] for the tip. Video below.

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Pre-Web Hardware Connects To The Web

We’re not quite to the 25th anniversary of the world wide web, but that doesn’t mean the greatest innovation in information distribution since [Gutenberg]’s press can’t be celebrated a bit early, does it? [Suhayl] is throwing some of his hardware into the ring, and loading up the first web page with a modem from the mid 1960s and a teletype from the mid 70s. No, no sane person would have ever done this 25 years ago, but it’s neat to watch in any event.

The hardware [Suhayl] is using includes a Livermore Data Systems modem. It’s a finely crafted wooden box with an acoustic coupler on top, and a DB-25 connector on a side that connects to a terminal or computer via RS-232. If that Livermore Data Systems acoustic coupler modem looks familiar, you might be right. This modem was demoed back in 2009 by [phreakmonkey]. It’s an impressive little box that can connect to a remote system at up to 300 baud.

The I/O is handled by an ASR-33 teletype. This was the standard way to connect to computers and mainframes before we were all blessed with video terminals and TV typewriters. The whole setup connects to a Unix system with a much more familiar Hayes modem, runs a text-only browser, and retrieves the first web page as it was served up at CERN some 25 years ago.

Spin up an old hard drive with a solenoid motor

Just about all of us have a few old hard drives in our junk box. There are a myriad of projects out there to put them to work in new and interesting ways. One of those ways is to turn your hard drive into a solenoid motor of sorts. (YouTube link) This isn’t a new hack, videos of it have been kicking around the internet for years. [black1985vette] gives a pretty good explanation of how he’s done it. He used a piece of brass as a connecting rod between the drive head and a pin mounted off-center to the platter hub. One of the platter mounting screws provides the perfect place to set the pin. A bent safety-pin rubs the center of the hub, which is partially insulated with tape. When the pin contacts the hub, the drive head is energized, pushing the whole assembly around. The mass of the platters acts as a flywheel, carrying the motor the rest of the way around.

[Pulverrostmannen] performed a similar mod, though he used a micro switch to time the drive head. Rather than a brass connecting rod, [Pulverrostmannen] used a spare head. With a simple transistor circuit acting as a speed control, his hard drive motor revved up to around 1560 RPM, which is pretty respectable for a bunch of junk parts.

So next time you’re stuck in on cold rainy weekend, pull out some of those old drives and get hacking! Click past the break to several of these projects in action.

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Fixing Sega Cartridges With Old BIOS Chips

For one reason or another, [Dragao] has an old Sonic The Hedgehog cartridge that throws an illegal instruction somewhere in the Marble Zone stage. While the cause of this illegal instruction is probably cosmic rays, how to repair this cartridge isn’t quite as clear. It can be done, though, using BIOS chips from an old computer.

[Dragao] got the idea of repairing this cartridge from Game Boy flash carts. These cartridges use chips that are a simple parallel interface to the address and data lines of the Game Boy’s CPU, and Sega Genesis / Mega Drive flash cart would work the same way. The problem was finding old DIP flash chips that would work. He eventually found some 8-bit wide chips on the motherboard of an old computer, and by stacking the chips, he had a 16-bit wide Flash chip.

To program the chips, [Dragao] wired everything up to an Arduino Mega, put a ROM on the chip, and wired it up to the old Sega cartridge. Surprisingly or unsurprisingly, everything worked, and now [Dragao] has a fully functioning copy of Sonic The Hedgehog.