Building a new motherboard for a TRS-80


The TRS-80 Model 100 was an amazing piece of kit when it was released. Able to run for a week with just four AA batteries and smaller than some laptops today, this portable version of the TRS-80 saw action with war correspondents covering the Falklands invasion. A pedigree a MacBook Pro will never be able to live up to, it seems.

[Hudson] picked up a non-functioning Model 100 with the express goal of replacing the 30-year-old electronics inside with an updated motherboard – and also pull up our retro site in the process. Armed with a Teensy++, [Hudson] pried open his ancient computer and set to work interfacing the display and keyboard to his AVR dev board.

The LCD display in the Model 100 has a resolution of 240×64, driven by ten Hitachi HD44102 display drivers. Each of these display drivers are responsible for the pixels in a 50×32 rectangle on the screen and are interfaced with a 30-bit wide bus consisting of chip select lines, and 8-bit data bus, and a few other random control lines. [Hudson] plugged this 30 pin header into his Teensy++ and after a bit of ingenuity regarding the strange electrical requirements of the LCD, was able to control every pixel on this 30-year-old display.

The next order of business was interfacing the keyboard with a modern microcontroller. The keyboard is laid out in a normal matrix, but with a few oddities: characters like ~, |, and curly brackets aren’t present on the Model 100. After working these problems out, [Hudson] set to work on a VT100 terminal emulator. This allowed him to run vi and lynx, enabling him to pull up the Hackaday retro site in a wonderful forty-column text mode.

Future improvements to this redesign include designing a proper PCB to replace the current protoboard design. The original Model 100 included a text editor and programming language, and adding a Forth implementation isn’t out of [Hudson]’s grasp. It’s an awesome build, and an excellent improvement that will allow [Hudson]’s Trash-80 to see another 30 years of use.

Giving the TRS-80 CoCo a 44 color display

As a relic of the early 80s, the TRS-80 Color Computer couldn’t display very many colors. By default, the CoCo could only display 8 colors on the screen at a time, but [John] figured out a way to increase the number of colors displayed using a very simple trick that surprisingly isn’t found in original CoCo games.

The TRS-80 Color Computer uses a Motorola 6847 video display generator to produce color graphics on its display. There are several graphics modes available to CoCo programmers, including a high-resolution black and white mode, and two four-color modes using red, green, blue, and yellow or buff, cyan, magenta, and orange.

These color palettes are extremely limiting, and usually switching between these modes produces a lot of flicker. [John] figured out if he switched the color pallets every 1/60th of a second (i.e. during the vertical blanking interval), he could display 44 colors on the CoCo.

It’s a clever little hack to increase the color palette of the CoCo, and in our opinion should be in the running for winning this season’s Retrochallenge. Sadly, [John] is judge for the Retrochallenge this time around, so he’ll have to settle for earning a Hackaday merit badge.

Arduino Taipan! clone stays true to the original


Fans of vintage Apple ][ and TRS-80 games will undoubtedly recognize the image above in short order. Taipan! was a popular game in its time, and [Simon] decided it was a great title to try recreating with an Arduino.

His goal was to use a standard Arduino Duemilanove to reproduce the game, rather than opting for a Mega or something like the Raspberry Pi. Seeing those two options as “too easy”, he ventured into the project with some self-imposed limitations, making it a more fruitful adventure.

In the end, [Simon] had to use two Arduinos – one to control the gameplay and another to run the display. Simon tucked both boards, a keypad, and an LCD screen inside a first run copy of Tai-Pan, a move that is sure to please Apple aficionados and Xzibit fans alike.

[Simon] made sure that no detail was overlooked during the port, making sure to include every line of text as well as every bug found in the original game.

Check out a video of the finished project below, and be sure to swing by his site for a very thorough build log.

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Raspberry Pi finds itself inside a TRS-80 Model 100

This TRS-80 Model 100 is a lot more powerful than you might think. That’s because [Karl Lunt] is using it as an enclosure for his Raspberry Pi board. Since the ARM-powered device comes sans-enclosure it’s fun to see a retro choice like this one. And having had to go out and buy a USB keyboard to use our own RPi, we appreciate [Karl’s] solution for using the original keyboard as an input device.

Above you can see that he’s using an LCD tv as the display. For now that connection is made using the composite video output, which explains the fuzzy image. To the right of the TRS-80 a standard wall wart connects to the barrel jack to provide power. [Karl] scrapped a USB cellphone charger in order to connect from the barrel jack to the micro-USB jack on the Pi board. The ribbon cable to the left lets him get at the I/O header without opening the case.

In order to use the keyboard he patched into it with a Teensy board. That connects to the USB port on the RPi, sending HID keyboard commands based on what it received from the user. We like this option as it give you the ability to pre-process keystrokes (ie: you can code your own custom macros that the Teensy will listen for). Right now the Model 100’s LCD screen isn’t hooked up but he may add that in the future.

Hackaday Links: June 12, 2012

Amazing 3D rendering in real-time

Ah, the 90s. A much simpler time when the presenters on Bad Influence! were amazed by the 3D rendering capabilities of the SGI Onyx RealityEngine2. This giant machine cost £250,000 back in the day, an amazing sum but then again we’re getting nostalgic for old SGI hardware.

Well, Mega is taken… let’s call it Grande

[John Park] needed to put something together for last month’s Maker Faire. A comically large, fully functional Arduino was the obvious choice. If you didn’t catch the demo last month, you can grab all the files over on Thingiverse.

Is that an atomic clock in your pocket or… oh, I see.

Here’s the world’s smallest atomic clock. It’s made for military hardware, so don’t expect this thing to show up at Sparkfun anytime soon; we can’t even fathom how much this thing actually costs. Still, it’ll be awesome when this technology trickles down to consumers in 10 or 20 years.

Converting a TRS-80 keyboard to USB

[Karl] is working on an awesome project – putting a Raspberry Pi inside an old TRS-80. The first part of the project – converting a TRS-80 keyboard to USB – is already complete. We can’t wait to see this build finished.

 A DIY Propeller dev board

Last week we complained about the dearth of builds using the Parallax Propeller. A few noble tinkerers answered our call and sent in a few awesome builds using this really unique micro. [Stefan]’s Propeller One is the latest, and looking at the schematics it should be possible to etch a single-sided board for this project. Awesome work and thanks for giving us a weekend project, [Stefan].

Controlling robots with a TRS-80

[DJ Sures], mastermind behind the EZ-B Bluetooth Robot controller, sent in a really interesting build where he controls a robot with a 1983 TRS-80 computer.

The robot in question is [DJ Sures]’ adorable WALL-E we’ve seen before. WALL-E is controlled through a Bluetooth connection to a desktop PC with the EZ-Builder hardware and software package.

To get the Trash-80 talking to WALL-E, [Sures] connected a tiny Bluetooth module to the TX pin of the 6402 UART. It’s a very, very simple modification that adds a Bluetooth serial connection to one of the first notebook computers. After syncing the TRS-80 and WALL-E to the computer running EZ-Builder, it’s a piece of cake to make the robot respond to the clanging of a 30-year-old keyboard.

There’s a video of [DJ Sures] going over his build after the break with a wonderful demo of WALL-E freaking out to a little dubstep. Check that out after the break.

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Giving an old Atari computer a much needed upgrade

As a kid, [Boisy] cut his teeth on the TRS-80 Color Computer. It was a wonderful machine for its day, featuring a relatively powerful Motorola 6809 CPU. Although his CoCo was theoretically more powerful than its Commodore and Apple contemporaries, the graphics and sound capabilities of [Boisy]’s first love paled in comparison to his friends 6502-based machines. A little jealously and thirty years go a long way, because now [Boisy] is adding a 6809 microprocessor to the 6502-based machines Atari put out.

[Boisy]’s goal for his Liber809 project was simple: Put a 6809 CPU in an Atari XEGS and get NitrOS-9, the Unix-like OS for the TRS-80 CoCo running on his Frankenputer. After a few months of work, [Boisy] completed his goal and more so: the Liber809 also works on the Atari 1200XL.

To put [Boisy]’s work in perspective, it’s like he took a Macintosh from 1993 and made it run on an Intel 486. While that’s not a terribly accurate analogy, we hope our readers will understand the fortitude needed to make a computer run on a completely different processor.

After the break, you can check out a neat demo app written by [SLOR] from the AtariAge forums showcasing a 6809 running in a machine designed for a 6502. Awesome work for all involved

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