SpritesMind.Net

OK. I just chose a quad nand because the nand is more versatile than the inverter, I might use the other gates for something else...

I know it works well (besides the harmonics problem) because I've already mounted it and saw the wave on a 100MHz scope, that's why I created this topic...

Good luck giving your MD a über OC

Thanks, I wont be easy becuase my Vcc is around 3.6 Volt, I think it limits the overclockability (!?) of the cpu...

The YM2612 and the MB3514 are powered with 4.2V (anything lower the YM will produce wierd noises)

[OFFtopic]
I did it because my VDP is an ass, it's very hot @5V so I reduced to the minimum possible, (at 3.3V there is some tile corruption and locks)

And the 3.6 voltage makes possible connecting to new devices that only support LVTTL, cool eh?
[/OFFtopic]

My MD1 clone went pretty hot... I put heatsinks on the chips... my MD2 does get only warm...

I had to increase my DCs SH-4 vcore to overclock it... and I guess your 3.6volts will be a problem...

Well for now it isn't a problem after all and it is running perfectly @ 13MHz, the dotclock...

No graphic glitches, no locks, always sound, so I guess I can push even further hehe..

I am targetting for the highest frequency I can get, while maintaning everything perfect (like it is now).
Probably I won't overclock to an extent of seeing crap on the screen and/or locks every other second...

Well, around 16MHz you'll probably get some issues.... my MD2 VDP goes crazy if the clock is above 14MHz, 10MHz is the most stable...

You may find this interesting : http://epicgaming.us/?p=4

Wow there are some insane clockings: 25~29MHz!, umm I'm expecting my MD to work flawlessly with a clock of around 16MHz(like you said), but I don't have many crystals... I do have a 16 MHz one though

Best shot would be building a variable frequency oscillator with a varicap diode, but I only have a concept idea, never tried to mount it, I dont even know exactly how to make the circuit... (simulating one at the moment)

What I'm planning to do is building the variable osc, test the ultimate stable frequency, get a crystal can closer but lower to that frequency, mount the oscillator with that 74AC00...

You might look at these. The ST1507 or ST1517 would probably suit you, depending on the frequency range you need.

http://www.pericom.com/products/timing/ ... s/vcxo.php

Yeah one of those would be great, but i'm sure that is expensive as hell, and they are from USA (expensive shipping for 1 unit), so probably I'm going to build one from scratch...