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***Darksaviour69*** · October 2nd, 2009, 11:05

Originally Posted by spinksy

I havnt tryeed the snes emulater - I dont even know where to download it from......

http://dreamcast.dcemu.co.uk/snesindex.php

**MAXIMUSpowers** · October 3rd, 2009, 14:40

Hey Spinksy. Yeah im pretty experienced with a soldering iron. Try clocking it to 220mhz and make sure the wire from the oscillator to the clock feed is as short possible because this can cause faults. This should help stop the DC from crashing and may help the VMU work also as it is at a lower clock speed. Id be interested to know the outcome of this as at the moment im not wanting to overclock my DC because of the lose of function. If it worked well at 220mhz id just leave it at that without a switch.

Dont forget the Battery mod. I replaced the internal battery of my DC and Saturn with 2x AAA's. The battery should last a lifetime. Highly recommended - especially for Saturn as you lose all your saves when the battery dies.

**JLF65** · October 3rd, 2009, 17:54

Instead of running the clock through the switch, add a multiplexer that connects to the switch. Run both (all) clocks to the multiplexer. That way the switch just runs the select line on the multiplexer and cannot affect the quality of the clock. The multiplexer can be quite a bit closer to the oscillators than the switch, making the resulting signal better. Be sure to use high speed TTL since we're talking > 200 MHz signals here.

Also, remember that the higher the frequency, the closer to the surface an electrical signal runs. So use the largest wires you can for the clocks. Using 30 gauge wire would not be prudent for this sort of thing.

**MAXIMUSpowers** · October 3rd, 2009, 18:58

Hi JLF65. Do you think VMUs will work at 220mhz or do they have to be connected to a DC at 200mhz?

**JLF65** · October 4th, 2009, 19:32

Originally Posted by MAXIMUSpowers

Hi JLF65. Do you think VMUs will work at 220mhz or do they have to be connected to a DC at 200mhz?

Don't know. I haven't looked at the VMUs much other than a brief glance over the dev tools available, or how to use them from DC homebrew. So I'm not sure from where the overclocking problem derives. I know they use a higher clock when plugged into the DC (because power isn't an issue then), but I have no idea if that clock is internal or comes from the DC.

If I had to guess, I'd say the DC uses hard-coded loops for timing somewhere in the VMU libs that don't wait long enough when the DC is overclocked. That's the most common reason for peripheral failure due to overclocking the main CPU. PCs suffered from that for a long time - every time a new faster CPU came out, stuff would fail because everyone was using software loops for timing. Intel specifically made one instruction slower to try to help alleviate that problem.

**spinksy** · October 4th, 2009, 21:27

Well the oscillator and swtich are currently outside the DC and mounted in my custom casing below my DC (this is where I was going to put my DC dvd player that I planned and if I ever make a hard drive for my DC it will also go in here

)
quick pic

As you can imagine theres quite abit of wire (roughly around 20-25cm) from the oscillator to the chip - but on the new DC I'm now finishing I'm keeping the length of the wire to as short as I can. (On the new one I've nearly finsihed I've got an internal VGA mod, and a few other bits - I'm also going to have it so I can change the oscillator crystal easily)

I downloaded the snes4all disc and it plays perfect:thumbup:

**MAXIMUSpowers** · October 9th, 2009, 19:43

Hey spinksy. When you use the overclocked DC with a normal VMU and try to save does it corrupt the save file? This is the problem I have with using my overclocked Megadrive with carts that have save options on them.

I am thinking about overclocking my DC but I think id have 3 options 200mhz, 220mhz and 240mhz. Id only add the 220mhz option if it was possible to save to the VMU.

**spinksy** · October 12th, 2009, 00:13

Originally Posted by MAXIMUSpowers

Hey spinksy. When you use the overclocked DC with a normal VMU and try to save does it corrupt the save file? This is the problem I have with using my overclocked Megadrive with carts that have save options on them.

I am thinking about overclocking my DC but I think id have 3 options 200mhz, 220mhz and 240mhz. Id only add the 220mhz option if it was possible to save to the VMU.

I havnt tried saving on a Sega vmu - I've been using a third party one. I've played Power Stone 2 with my DC in 240 and 200 mhz and saved with both and it's been fine.

Me and my mates were playing Power stone 2 earlier on 200mhz and it seemed well slow - we switched it to 240mhz and it was awesome!!

**MAXIMUSpowers** · October 13th, 2009, 00:01

Hi Spinksy. Can you see what it does to VMUs when clocked at 240mhz - Im hoping it doesnt corrupt the VMUs when they are present when overclocked. Also what memory card are you using when at 240mhz. Does anyone know of a list of memory cards that work at 240mhz. Do you have any over heating issues? Im thinking of clocking mine to 230.4mhz