Atari ST TOS Replacement

Posted by admin on July 20, 2023
General / No Comments

I have always been an Amiga user/fanboy. After my Atari 65 XE which I got at a very early age, and before I was even aware of what the landscape of home computers was at the time, I got my first Amiga 500. Boy did I fall in love with it! Then came the Amiga 1200 and then … well … the Amigas died and I had to move on.

At the same time, the main rival of the Amiga for its price range was the Atari ST. I did not know much about the ST back then, only that it was an inferior machine when it came to graphics capabilities compared to the Amiga, and that it came with MIDI interfaces built in. Not that I knew exactly what that meant, but in my mind the Amiga was superior when it came to graphics and the Atari had more capabilities when it came to audio. Well, I was wrong on that part since I only recently discovered that the Amiga was ALSO vastly superior at the audio department, with 4 PCM channels, as opposed to 3 FM channels (based on the AY-3-8910 audio chip also used in many 8 bit computers like the Amstrad CPC and the ZX Spectrum as well as some old arcade machines like 1942 and Frogger and only had synthesis capabilities and no samples).

But enough about the history lesson, this is not what this blog post is about. Since I recently got my first Atari ST computer (an Atari MEGA ST 2) I am starting to learn a few things about it and how everything worked in Atariland. My ST came with a monochrome monitor, capable of a 640×400 black and white image and not much more. This was a very high resolution for the time and the Atari OS (TOS and GEM) looks very crisp on it, despite the complete lack of color. The only issue was that my OS was in German. While I occasionally like German and speak it a bit, I do prefer my OSes to be in English. But looking into how I would change that, I discovered that in Atariland, the OS is in ROM on the motherboard. Oh well, time to get my trusty screwdriver and open it up.

After ordering a new set of English TOS chips (TOS 1.04 which was the last version released for non Enhanced versions of the ST – the E in STE models), waiting for a few days (installing a Gotek inside the ST while waiting) they are here. Time to replace the ROMs!

Looking around inside the Mega ST, I found the 6 chips that needed replacement, next to the mighty 68000 CPU. Thankfully, the chips were not soldered to the motherboard but rather sat on sockets so they could be easily removed and replaced.

Removing them was rather simple, trying not to bend their little legs too much so that they broke. This is what they looked like after being removed.

Putting the new chips was even easier. Just align the legs and push gently and evenly down.

Power on and … nothing. No fan spinning, no Gotek getting power. Nothing. This was a scary moment until I realized that I had relied too much on the labels orientation to notice that there is a notch on the side of each chip which has to match the notch on the motherboard chip sockets.

After removing them once more, and placing them back correctly, it was a success and TOS is now in English.

So success!

Master System 2 Power Led Mod

Posted by admin on January 06, 2022
DIY, General / No Comments

Since we started modding the Master System 2 on the previous post, I thought I should go ahead and fix another omission of the system. A freaking power led! How would you know when the system is on without one? Well, that’s an easy fix but, since I already mentioned in the previous post that I don’t like modifying these old consoles in a irreversible way, I decided to go the extra mile and 3d print a new power button with the necessary space to let a led shine through it, so I could save the original part.
Link here:

So first thing is first. I already had a bunch of color cycling 5mm leds lying around from my NES mod, so I decided to use one of these as my power led for the SMS2. These are quite fun, since they automatically cycle through many different colors when power is applied.

The way you connect the led is by using 2 pins of this little thingy (which is a Voltage Regulator), which is accessible inside the Master System 2 even without removing the metal shield:

I used a red wire for the positive and the black one for the negative pin of the led. I also used a 75Ohm resistor to connect the positive side (you can see it above inside the red heat shrink).

The led fits nicely inside the 3d printed power button that replaced the original one and the pins and wire come out of the side, so it does not affect its usage which is to actually, well, power the system on and on by flipping the switch below it.

And that is all you need to do. Here is a video of the result, in real life it does not shine so brightly and it looks very nice when powered on.

Modding an NES – PAL-E console controller support hack

Posted by admin on June 05, 2021
DIY, General / No Comments

A little known fact about the NES is that there are versions of the console that do not support all the controllers out there. The PAL version that came with controllers that have the NES-004E engraved on the back ONLY support controllers with this engraving and nothing else. Controllers from the NTSC version will not work and nor will any knock-off controllers from China.

I recently replaced my controller’s insides with the excellent DIY kit from 8BitDo that turns the original controller into a wireless version that works just as well.

I am using this with the also excellent NES retro receiver and works flawlessly. Since I am using the original chassis and buttons, the feeling is almost identical to the original controller sans the cable. The system worked fine on my PAL NES-E console as well.

But all that changed when I bought a couple of (admittedly very nicely built) knock-off controllers from China. I plugged both on either port on my NES and nothing seemed to work. It would be a huge coincidence for both the controllers to be faulty (I knew the console and both ports worked) so I investigated further.

It turns out that my console only supported NES-004E controllers (the 8bitdo receiver obviously is handling the issue fine). By disassembling the console, I noticed that each controller port was connected to some kind of board which in turn was connected to the main board. These boards had several diodes that obviously prevented other versions of the NES controller to work.

The solution turned out to be surprisingly easy. All one needs to do is bridge all the diodes (essentially bypassing them). You could also remove the whole board and connect the cables directly on the port but I felt this solution was easier to do and more elegant.

This modification is only useful if your NES has this board between each controller port and the main board and you have controllers you want to use that are not recognized. It can also be done in the same way on both ports. Doing this mod does not have any drawbacks, the original controller work just fine. But now, your NES is controller-region-free!