9MHz mod

[metalliqaz]

I'd like to do this mod on my genesis.
I can't find any documentation anywhere about it tho. I can find info about a 13.x MHz mod, taking a line from the cart port (IIRC), but nothing that helps me for finding a 9MHz osc.

evildragon, i know you've done it, care to share the wizdom? :)

-d

[evildragon]

I got a 9MHz oscillator just by looking around on old scrap boards... I got a 4-pin...

the one on epicenters site does explain how to use the oscillator..

[metalliqaz]

Meh. You have to add your own can? poopie.

-d

[metalliqaz]

Man, I am having the darndest time finding a 9 MHz TTL oscillator...
I think I'll have to order 50 or so when I finally find one.

-d

[TheGZeus]

why 9, specifically?

[metalliqaz]

Well, I was under the impression that 9 MHz was a good speed that would do a good job reducing lag/slowdown, but would be slow enough to not cause any major glitches, and also not require booting the genesis at 7.6 and halting before overclocking. I have since read that some systems can go as high as 11 or even 12 MHz before things start screwing up. oh well.

-d

[evildragon]

I believe Rob and Epicenter have said that 10MHz will work..

But I do kinda consider 9 to be the fall back number..

[metalliqaz]

I settled on a 9.2 MHz can that I found at Digikey

-d

[Epicenter]

Bump from hell. The max stable speed your system can attain is affected by numerous factors including system revision and CPU type. I personally find 10-12 MHz to be the best speed to aim for; you can find oscillators for many different speeds at digi-key.com in small quantities (but if your order is <$25 you get a $5 surcharge. Not too bad.) There's the onboard ~13 Mhz EDCLK signal but you will want to clean it up before use, and you might experience odd arbiter-based issues with that signal, like missed writes to the Z80 causing sound to cut out or music tracks fail to change at times. So a separate oscillator is a better solution.