What do you think about my MD2 ?

[Tiido Priimägi]

Here's some pics of my super modded MD2, what do you think about it










It does/has :
68000 can be overclocked to 10MHz (MD2's don't OC well)
Z80 can be overclocked to 4.5MHz
RGB output(SCART), RGBHV output(VGA connector, few monitors support it)
4 VFD tubes that say "SEGA"
Crystal Clear Audio Mod - The ultimate sound fix for your system, Fusion pales in comparsion !!!
No TMSS mod (not on pic, I'll add if requested)...
Some extra LEDs
Blood mod

[Richter X]

Blood mod?

I'd love to do the audio mod on mine, as well as something to make the video not look blocky (composite is crap on this thing). However, I have a SegaCD connected on mine so I wanna see what you can do that first. That, and I've only handed a soldering iron once in my life. >.<'

[l_oliveira]

While I would not do that on my own Mega Drive, hacking is about making stock things fit one's personal preferences. Pretty nice hacking.

I managed to overclock a korean botleg Mega drive to 15mhz, but for that to work, I had to change the PSRAMs (68000 rams) to 15 NS SRAMS, the 68000 was changed for a 16MHz version and the Z80 I changed from Z80 A to Z80B (6MHz).

The clock for the Z80 still kept the original ratio with the 68000 clock because the chipset was model 1 style.  A SEGA VDP can not keep up with that high clock but the pirated VDP would do it just fine.   Only original cartridges were playable on the overclocked MD because Eproms cannot keep up with a 16MHz 68000.

Using an older MD or dividing the clock from the 68000 clock for the Z80 (keeping the original ratio) might increase compatibility greatly while playing with overclock on. 


I really enjoyed your idea of using the oscilator chip from 4 pin quartz oscilator boxes.

Again, great hacking !

[l_oliveira]

Sorry about this second post, but edit isn't working for me ... It just shows a green bar "loading" and sits there forever (I'm using firefox)

I wanted to add that if you turn off the third tube middle segment it will look exactly like an G.  Thus making it read  SEGA, not SE6A lol.

[Tiido Priimägi]

Thanks for the tip on VFD

Metal can osc opening can be a bit pain, they are made of metal and get a bit hot... you need to use fingers for that since if you use some tweezers you might end up frying the thing due to heat which generates when using a grinder to open one...

I don't have any SRAMs which I could use, and it would not help much since the VDP will go crazy when you've reached 11MHz...
I am a MD developer and I just have the OC stuff to test stability of my things under "extreme" circumstances

And yeah, changing master clock is good, you just need to make sure VDP gets the original clock, and it would be nice if YM2612 gets it too You will need RGB to see colors though...

[l_oliveira]

Not really. The color carrier comes out of the VDP itself. So if it's getting the original clock the color carrier will still be the original frequence.

Funny enough but on the earliest MD (3 SEGA chips version) the clock for the Z80 is not from the VDP, but comes from one of the two smaller custom chips.

[Tiido Priimägi]

Last time I tried master clock changes, I didn't get any colors unless I used RGB... I have a 3 chip early MD1, I'm getting a 2chip one soon... early models don't OC much, only 12MHz, beyond its not stable, even 12 isn't too stable, still a bit better than MD2, but I prefer MD2 for its superior sound quality (the Yamaha YM2612 is not very good, compared to the integrated one in MD2 and onwards).