Sonic and Knucles Playable on radica!!!

[bevo]

Wow just seen DevSter's page after an earlier post by dman762000.

Has anyone tried it, the bank switching would make sense. This means radica can be a full genesis replacement.

[EnterTheHatrix]

... You CAN turn Radica into a full genesis...

Ben should have a guide on his site, but unfortunately since he switched to this new system, most of his old pictures dont work.

[Unidentified Assilant]

Radica Genesis Portables +1

=)

[Turbo Tax 1.0]

link please. this sounds cool how hard is the mod?

[jeroen]

search google for devster. The mod seemed cool.

[Skyone]

>> More Games Mod (aka Devster's SNK Mod)

To play more games, like Sonic 3, Sonic and Knuckles, and Street Fighter (the 40mbit version), you will need to perform a modification to the Radica's banking hardware. Without doing this mod, a stock Radica modded with an external cartridge port will not be able to play these three games in your collection (or even more games maybe).

Bob says: So what causes my Radica to crash when playing these games?? ???
Well Bob, the answer is simple -- when games such as Sonic 3 and SNK (Sonic + Knuckles) start up, these games will write a value into register $A130F1. Sonic 3 will write to this register to enable and disable writing to its save game memory. Games such as Super Street Fighter, or some other Hong Kong bootleg will write into this location to switch memory banks. The Radica uses the register array from $A13000 to $A130FF to switch in different games into $000000 - no wonder the Radica crashes when playing sonic 3 (the Radica will bankswitch the memory -- bad bad)! Why don't we just rip off all the bankswitching chips???? To be compatible with Street Fighter, we can't just ignore this register, we'll need to put it to good use.

We will need to connect an extra signal to the cartridge called /TIME. On the Radica board, this signal is located on pin 9 of the chip marked 74HC174 (or HC174 for short) on the bottem of the Radica board. This chip is a 16 pin Hex-D Flip Flop with a clear (refer to the Banking Scheme for the function of this IC in the Radica). You will need to lift pin 9 up, and then solder a wire going to VCC or 3.3 volts, pulling it high so that we don't have the pin floating. You will then need to connect a wire from the pad of pin 9 to your cartridge slot on pin B31. If you've already hooked up your cartridge slot, then B31 is located directly across from the +5v supply (the +5v supply closest to the data pins, eg: D11). That's all you need to do - hook up two wires. The first one to the '174 might be optional, but we connect it anyways to ensure that the flip-flop doesn't get written.

Public service announcement: The 74HC174 has 16 pins on it. The other chips are 74LS32 or-gates, which contain 14 pins. These chips can be removed, but I think it's worthless since the electrical current saved is very negligible (around the uA). If you are going to remove these chips, refer to the banking scheme in order to get the higher address lines A21-A16 working again.

In short, to perform this mod, do these steps:

1. Lift up pin 9 from the 74HC174 IC (do not break it! Just lift it up - you will need a soldering iron to do this =D!)
2. Connect a wire from the pin you lifted up, and connect it to pin 16 of the '174 (or any other +3.3 volt supply)
3. Connect a wire from the pad that pin 9 use to rest on, and connect it to pin B31 on your cart slot
4. Start playing Sonic 3!


An artist's rendering of pin 9

I have no pictures of this mod, but I'm hoping that there'll be plenty of pictures of this two wire mod once people start doing it !

Writing to Sonic 3's FRAM will not work on this mod. A write enable signal from the Radica must be generated in order to write to any cartridge memory. This mod, and obtaining the parts for it goes beyond the scope of many hobbyists.

from http://devster.monkeeh.com/sega/radica/

I suppose this would work, it'd be more efficient to replace the bank, but hey, this is fine!