An Atari Graphics Chip, Ready For You To Build

November 10, 2019 by Jenny List 27 Comments

The most notable of the home computer and console hardware from the 8-bit golden era didn’t get their impressive sound and graphics from off-the-shelf silicon, instead they relied on secretive custom chipsets to get the edge over their competitors. Unfortunately for vintage gaming aficionados, those chips are now long out of production and in many cases there’s little information to be had about their operation.

Which makes discovery of the schematics (PDF link) for the “Tia Maria” graphics chip found in the Atari 7800 console an unusual occurrence, and one which should be of special interest to the emulation community. They can be found alongside the rest of the Atari Museum’s 7800 information.

That such a useful document is available at all is due to a lucky find in a dumpster following the demise of Atari, when a treasure trove of documents was discarded. It seems that the existence of these schematics has been known within the Atari community for some time, and we expect before long this information will find its way into FPGA implementations of the 7800; especially since the system features nearly complete backwards compatibility with the massively successful Atari 2600.

When that happens we hope we’ll be able to bring it to you, but it’s not the first time someone’s made an Atari on an FPGA.

Via RetroRGB

Header image: Bilby [CC BY 3.0]

Amstrad Portable Gets A Modern LCD Transplant

October 30, 2019 by Tom Nardi 5 Comments

Playing classic games on the real hardware is an experience many of us enjoy, but sometimes the hardware is just a bit too retro for modern sensibilities. A case in point is the miserable monochrome LCD that was originally installed in the Amstrad PPC640 portable 8086 PC that [Drygol] recently picked up. He decided that his portable Amstrad sessions would be far more enjoyable if he swapped it out for a display that didn’t have 30+ years on the clock.

To quell the complaints of any of the vintage hardware aficionados out there, it’s worth mentioning that the original LCD was actually damaged and needed to be replaced anyway. Granted [Drygol] could have tried to find a contemporary panel to replace it with, but looking at the incredible before and after shots of the modded PPC640, it’s hard to argue he didn’t make the right decision by throwing a modern display into the otherwise largely original computer.

Getting the new LCD’s PCB ready for installation.

[Drygol] says he picked up a cheap 4:3 LCD TV on eBay, and as luck would have it, found that the new panel dropped perfectly into the original frame. Getting it buttoned back up required the removal of the RF can and all the female connections on the TV’s PCB, plus he had to cut some holes in the back of the display enclosure to mount the LCD’s controls, but overall it looks very stock.

Of course, getting the new LCD display in the original frame was only half the battle, it still needs to be connected up to the computer somehow. To get everyone playing nicely with each other, [Drygol] is using a commercially available MDA/CGA/EGA to VGA converter that is installed where the batteries would have gone originally. Wired to the PPC640’s external monitor connector, it allows him to drive the new display without having to use the original LCD interface.

[Drygol] has made something of a name for himself by performing some of the most impressive restorations and modifications of retro hardware in recent memory. From the unbelievable work that went into repairing a smashed Atari 800XL case to his gorgeous custom Amiga A500, his projects are sure to please the retro hardware lovers in the audience.

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Repurposing A Toy Computer From The 1990s

October 14, 2019 by Tom Nardi 24 Comments

Our more youthful readers are fairly likely to have owned some incarnation of a VTech educational computer. From the mid-1980s and right up to the present day, VTech has been producing vaguely laptop shaped gadgets aimed at teaching everything from basic reading skills all the way up to world history. Hallmarks of these devices include a miserable monochrome LCD, and unpleasant membrane keyboard, and as [HotKey] found, occasionally a proper Z80 processor.

It started, as such things often do, with eBay. [HotKey] found that the second hand market is flooded with these decades-old educational gadgets, often selling for just a few bucks. As it turns out, children of the smartphone and tablet era don’t seem terribly interested in a “laptop” from 1991. At any rate, he ordered about a dozen different models and started tearing into them to see what made them tick.

He found that the VTech machines of around 20+ years old were using the Z80 processor, and what’s more, they shared a fairly standardized external cartridge interface for adding additional software or saving data. Upon attempting to dump some data from the cartridge port, [HotKey] discovered that it was actually connected to the computer’s main bus. He realized that with a custom designed cartridge, it should be able to take over the system and have it run his own code.

After more than a year of tinkering and talking to other hackers in the Z80 scene, [HotKey] has made some impressive headway. He’s not only created a custom cartridge that lets him load new code and connect to external devices, but he’s also added support for a few VTech machines to z88dk so that others can start writing their own C code for these machines. So far he’s created some very promising proof of concept programs such as a MIDI controller and serial terminal, but ultimately he hopes to create a DOS or CP/M like operating system that will elevate these vintage machines from simple toys to legitimate multi-purpose computers.

We’ve seen VTech hardware hacked in the past, but it’s generally been focused on the company’s more recent hardware such as the Linux-powered InnoTab. It will be interesting to see if these educational toys can fulfill some hacker’s dreams of having a cheap and portable box for Z80 tinkering.

Extreme Refurbishing: Amiga Edition

October 11, 2019 by Bryan Cockfield 17 Comments

The last Amiga personal computer rolled off the assembly line in 1996, well over 20 years ago. Of course, they had their real heyday in the late 80s, so obviously if you have any around now they’ll be in need of a little bit of attention. [Drygol] recently received what looks like a pallet of old Amiga parts and set about building this special one: The Vampiric Amiga A500.

The foundation of this project was a plain A500 with quite a bit of damage. Corrosion and rust abounded inside the case, as well as at least one animal. To start the refurbishment, the first step was to remove the rust from the case and shields by an electrochemical method. From there, he turned his attention to the motherboard and removed all of the chips and started cleaning. Some of the connectors had to be desoldered and bathed in phosphoric acid to remove rust and corrosion, and once everything was put back together it looks almost brand new.

Of course, some other repairs had to be made to the keyboard and [Drygol] put a unique paint job on the exterior of this build (and gave it a name to match), but it’s a perfect working Amiga with original hardware, ready to go for any retrocomputing enthusiast. He’s no stranger around here, either; he did another extreme restoration of an Atari 800 XL about a year ago.

The Monotron, A Rusty Retrocomputer

October 5, 2019 by Jenny List 2 Comments

For many people, a retrocomputer is a classic machine from the past lovingly brought back to working order. But for some, the idea of a retrocomputer is wider than that, encompassing modern hardware that delivers to feel like a device from the past.

The Monotron from [Jonathan Pallant] is one such computer. It’s definitely a retrocomputer such as you might have found in the 1980s, but it’s running on a much more modern Tiva-C TI Launchpad dev board sporting an ARM Cortex M4.

The platform has been created entirely in Rust, and emulates what would have been a rather desirable machine in the early 1980s. With an 800×600 pixel 8-colour VGA display interface, 32k of RAM, and mono 8-bit audio, it already has a few simple demos and games running upon it. [Jonathan Pallant] has given more than one talk on its design and capabilities, we’ve placed one of them as a video below the break. There is even a PCB available which adds all the ports as well as a micro SD card slot for program storage.

We like the Monotron, and we look forward to seeing it develop. It’s an exciting time for retrocomputig with projects such as the RC2014 Z80 machine and the Gigatron TTL RISC processor, but is there space for an emulated one such as this? We hope so.

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Windows 3.1 Screensavers, Now On Twitter

September 23, 2019 by Zoe Skyforest 14 Comments

Back in the early dawn of the GUI age, cathode ray tubes were the dominant display technology for the personal computer. In order to avoid burn-in of static display elements, screensavers were devised to help prevent this problem. Out of love for the software of yesteryear, [Greg Kennedy] has put together a bot that posts Windows 3.1 screensavers on Twitter.

A Perl script runs the show in this case. Screensavers are packed into “units”, which are loaded by the script. A basic Windows 3.1 environment is then configured, and loaded into a specially patched DOSBOX that allows automated demo recording in a headless environment. Once up and running, video is recorded of the desktop and subsequent triggering of the screensaver. After a couple of minutes, the recording is stopped, and FFMPEG is used to transcode the video into a Twitter-suitable format. It’s then a simple job of Tweeting the video using the standard API.

It’s a fun project that makes sharing old screensavers easy. Be sure to check out the Twitter feed @dot_scr. If you’re addicted to the vintage aesthetic, try this Apple ][ screensaver hack on your Linux boxen. Video after the break.

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Riding The Nostalgia Train With A 6502 From The Ground Up

September 19, 2019 by Dan Maloney 44 Comments

In the very early days of the PC revolution the only way to have a computer was to build one, sometimes from a kit but often from scratch. For the young, impoverished hobbyist, leafing through the pages of Popular Electronics was difficult, knowing that the revolution was passing you by. And just like that, the days of homebrewing drew to a close, forced into irrelevance by commodity beige boxes. Computing for normies had arrived.

Many of the homebrewers-that-never-were are now looking back at this time with the powerful combination of nostalgia and disposable income, and projects such as [Ben Eater]’s scratch-built 6502 computer are set to scratch the old itch. The video below introduces not only the how-to part of building a computer from scratch, but the whys and wherefores as well. Instead of just showing us how to wire up a microprocessor and its supporting chips, [Ben] starts with the two most basic things: a 6502 and its datasheet. He shows what pins do what, which ones to make high, and which ones get forced low. Clocked with a custom 555 circuit that lets him single-step and monitored with an Arduino Mega-based logic analyzer, we get a complete look at the fetch and execute cycle of a simple, hard-wired program at the pin level.

This is one of those rare videos that was over too soon and left us looking for more. [Ben] promises a follow-up to add a ROM chip and a more complex program, and we can’t wait to see that. He’s selling kits so you can build along if you don’t already have the parts. There seems to be a lot of interest in 6502 builds lately, some more practical than others. Seems like a good time to hop on the bandwagon.

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