All posts tagged sega

What if you have many retro consoles/devices and just one SCART on the back of your TV? You need a switch, of course! But nowdays it’s hard to find a good one… So why not build one!?
Since me and a friend of mine have 20-30 retroconsoles, which sometimes we likes to power on and play a bit, we need a solution to have a sort of “plug & play” system.
I found on YouTube and web that some people that built one by themself with some digital switches and a microcontroller and, with my partner in science, Dom, just drafted a sort of circuit to test if the project could be possible and it gave us good results.

Here we go!
Since I never handled this kind of signals I’ve done some research on how to draw the right traces on the PCB to avoid any serious interference as best as possible for me. Fortunately it was pretty easy.

The project is based on a mainboard composed by a PIC microcontroller, a main switch/selector and eight multiplexer, and a daughterboard (to be designed) to add eight more ports (up to two for a total of 24 inputs, not guaranteed until I’ll produce a prototype for the right tests). On the mainboard can be connected an 8×2 LCD character display (or biggher by modifying the firmware), two buttons for the input port selection and an IR receiver (not implemented yet firmware side, need to write the NEC IR library). The board can be powered by USB or by external 9-12V (adjusted to 5V by a stepdown IC)
The firmware is in MikroBASIC (yes, I’m lazy and this language isn’t the best for microcontrollers, I know).

(The board in pics is the prototype/rev 1.0)

The box works successfully! Except for some little problems that I’ll try to fix in a future revision.
– Initially a device with just A/V RCA had problem with another RGB SCART device connected. It should be fixed in this revision but need more tests.
– Two pin of muxes are not used yet, I’ll try to add other two pins to make them available for extras (es SCART + S-Video) for the next revision.
– Blanking and Aspect Ratio does not have any switch, they just use two diodes per port, so they are really not disabled. I’m thinking for a solution that I’ll test on a simulator before putting it on the next revision.

You can find PIC sources and EAGLE project on GitHub!

NOTE: I’m planning, for the next revision, as said, two more pin in/out to support also S-Video, and (probably, but not sure) a better management of blanking and aspect ratio pinout. If you’re planning to build one by using my schematic please try to wait a bit. :)
Unfortunately I cannot give you a release date, because I’m busy in real life, but I’ll do my best to fill that.

This project is “as is”. I’ll NOT assume any responsability on how you use this project and on any damage it can cause to any device of yours, people or things. Use it at your own risk!

Back in 1998 SEGA released a 128-bit console called Dreamcast.
It was a really pretty console, slim and powerful, unfortunately dropped early by SEGA because a REALLY BAD marketing.
The Dreamcast is still one of the most favorite hardware by geeks, after the PSX, and one of the coolest hack around is the BIOS replacement.
The Dreamcast DevKit, in fact, have a more beautiful BIOS boot animation than the retail one. Some rumors affirms that SEGA had in plans to release an update for the retail Dreamcasts to replace the boot animation.

This never happened.

After the pretty failure some people had the luck to obtain a DevKit machine and dump the BIOS out. The DevKit BIOS is pretty the same, in size, as the retail one and seems it is stored in the same chip. The only differences, animation apart, it’s region free and there are a bunch of bytes that after some hex edit permits it to run on the retail console.
After founding a Dreamcast at the flee market for only 10€ (but without any cable) I decided to find an how-to guide to try this mod:

I’ve bought the EEPROMS (MX29LV160TMC-90) on eBay, they’re really cheap!

It wasn’t hard to install the new chip over the older, like in the guide linked above. Just use a good soldering iron and a thin solder wire with a good flux, it REALLY helps!

Flashing DevKit BIOS on the new chip with a modified DreamShell present on the same link…

Switch cables to select original or DevKit BIOS

Since the console is open, why not add more “hacks”?
The Dreamcast was the FIRST console that supports VGA output natively (but games must be compatible, otherwise you’ll see only a black screen instead), so I’ve looked for a VGA hack guide.
There are on eBay also VGA cables, they should work really good and out of the box, but are very expensive (about 20€ actually). A VGA female port costs only 1-2€ and as well as a good pair of RCA female plug. Why RCA female plugs? Well to have stereo output to connect with an external amplifier! :D
On the same site I’ve found the schematic to install the VGA port, with the complete pinout to connect also the two audio channels:

Some tests…

Yes there should be another switch there. It’s to select “VGA out” and “Normal A/V out”.

And there’s the final result! (With a blue power on led mod! B) )

Thanks to Snake, my partner in science, for helping me with my bad english!