PyramidHead

Sep 10

ATARI Lynx II / Raspberry Pi - Part 1

I recently uploaded a video of my attempts to resurrect a dead Lynx II using a Raspberry Pi. You can find that here. Today I had a question on Twitter (from @pzkfw5) asking for more information & I guess it makes sense to answer here in case there’s any further interest.

I’ll have to split this over a few posts, starting with “What is the Lynx and what am I trying to do?”. Later I’ll move on to:

It’s all a work in progress. If you take a close look at the video you’ll see that most of the components are floating around on my desk rather than actually in the Lynx right now. I don’t yet know if it’ll ever be truly finished.

1. What is the Atari Lynx?

The Lynx was a battery powered, 8/16 bit games console with a colour LCD screen. It launched in 1989, where it was competing with the Nintendo Gameboy and later the Sega Game Gear.

http://en.wikipedia.org/wiki/Atari_Lynx

It was pretty advanced for its time. Back then the Gameboy was monochrome & your home computer would’ve been 16-bit at best. If you had a laptop at all it would’ve also been black & white even if you’d paid £3000+ for it.

My Lynx (technically a Lynx II) has been dead for 20 years.

2. What was my plan?

Like a lot of people. I bought a Raspberry Pi without much of a plan in mind for what I’d do with it. But I have a loft full of old computer ‘junk’, went hunting for something to put the R-Pi into and found this in a bag.

I opened it up, took the components out & poked around a bit. This is what the constituent parts of a Lynx II look like…

The upper & lower plastic casing

There’s a flex PCB mounted to the upper case which drives the buttons/DPAD. The cable dangling from this PCB (visible just below the orange Atari logo) can be connected to the Raspberry Pi GPIO pins to make all those things work under Linux. I found schematics online for the Lynx but still used a multimeter to double check which wires went where.

In the pic above, the connecting cable actually is connected to a socket, which itself is soldered to a strip plug that I can connect to the R-Pi. It’s not very pretty at the moment but it works.

Lynx II Motherboard

I’ve de-soldered & removed the keypad connector on this motherboard - Somewhat brutally. The quality of this desoldering will probably make hardware people cry.

LCD Screen & Backlight

The Lynx screen was impressive in its day. But now, the 160 x 102 resolution & HUGE power hungry backlight mean that I probably wouldn’t want to retain it even if I could.

3. Will it fit?

The case is physically big enough to easily contain a Raspberry Pi, but by the time I’ve added a screen, batteries, etc, it’ll be very tight, I think. 

Here’s how some of my replacement components stack up against the originals

Again, the Lynx II motherboard was every bit as impressive as the R-Pi in its day. VLSI means ‘Very Large Scale Integration’. Basically, miniaturisation through combining what would previously have been separate chips onto one bigger chip to save cost and space. The System-on-chip at the heart of the Raspberry Pi takes this to an extreme which wasn’t possible in 1989.

Here you can see the original screen (left) vs the new one (right). I found the new 3.5” screen on eBay & it’s a VGA (640 x 480) composite device.

As luck would have it, the new screen fits perfectly inside the plastic case ‘window’. There’s some cropping of top/bottom of screen but that’s fine for my purposes.

This pic shows the relative thickness of old and new screens. The bulge in the old screen is for the CCFL (flourescent tube) and the mirror to reflect all of the light back through the screen. The new screen is probably LED backlit, but could have a tiny CCFL tube, I haven’t poked around. Even with its controller PCB (blue) it’s maybe 1/3rd of the original screen thickness.

The only other thing missing is power. The Lynx originally ran on AAs but I’d rather see if I can fit modern LIPO batteries in there somehow. I have a couple of ‘mobile USB charger’ devices that I’m experimenting with.

Unfortunately my choice of screen complicates matters slightly - It expects a 12v supply while the Raspberry Pi needs 5v. So, eBay to the rescue again: I found a cheap step-up converter which will take a 5v input and supply 12v to power the screen.

It’s a very simple device (left) with a pin for ground, a pin for input (5v) and a pin for output (12v).

However, a mobile USB charger won’t provide enough current to power both the raspberry pi and the screen. So now I need either two batteries or one with two regulated outputs (which I have… More on that later).

I reckon that’s enough for a first post… Any comments/questions please let me know.

Feb 02

Keyrah! Wait, what?

So, what’s this?

If you answered ‘Commodore 64’, you’re close, but wrong!

This arrived in the post this morning:

The USB lead is a subtle clue as to what it really is…

It’s a handy device you can buy which converts most Commodore 8-bit computers into fully functioning USB keyboards. It even has two 9-pin joystick ports!

I have a few (*cough*) dead commodore computers & planned to turn one into a HTPC at some point, so it didn’t take long to open that up & screw this in.

Put it back together and it does exactly what it says on the tin: The donor C64 is now a USB keyboard which works anywhere that you can normally plug in a USB keyboard. In these pics, it’s connected to a Linux box where most of my emulator games live.

The joystick ports work by simulating keys, which means they work great with emulators (where most people will want to use these things). I guess they’ll also work with most PC/MAC games that work with keyboard input too, if you’re tempted to try your old joysticks with new games.

The switch alternates between two keyboard/joystick modes. One setting is meant for people who want to use their Commodore as a regular(ish) PC keyboard, while the other is meant for emulators.

I’m very happy with the quality of it. If you’re tempted, you can find your own here: http://www.vesalia.de/e_keyrah.htm

… But of course you’ll have to supply your own C64/C16/Vic20/C128/Plus4.