Question concerning MM1026AF watchdog...

Hey guys! I'm new to the forums, so please forgive my ignorance if this question has been addressed elsewhere; I freely admit that I am not the best at exhausting all possible search options in the browser ^_^.

Anyway, I am attempting to build a Star Fox 2 cart using a Doom pcb. I have a sort of makeshift schematic I found online which details the parts required, as well as the connections which need to be made (albeit, in a rather crude manner). It can be found here: http://consolemods.freeforums.org/starfox-2-battery-circuit-t42.html

So I understand I need a 12 nf capacitor, the battery (of course, otherwise this entire exercise is futile and dumb), and a 1k ohm resistor; the problem I'm running into is finding an equivalent watchdog to use in lieu of the MM1026AF chip.

This might seem an easy answer for some of you; I don't know. My knowledge of circuitry is rudimentary, though I am picking things up here and there as needed (for example, I've made 8 nes-in-a-cartridge mods, and have streamlined the process to where the final product is quite sleek). So I know the basics as far as soldering, choosing the correct gauge of wire, and how to translate an existing circuit board into a morass of wires and components; such as might gain the appreciation of the mad god Sheogorath.

However, that is as far as my education extends; all basic reverse-engineering stuff. So, when it comes to this particular chip I want, I do not really know what to search for. I have a .pdf file which contains the technical specs of the chip, but aside from absolute values concerning current and voltage, it's all Greek to me.

I've let this ramble on long enough; my apologies. I just like to fully explain my position, in order that whomsoever decides to help me may know, from the start, exactly the sort of mess they're venturing into . Any sort of help on this topic would be greatly appreciated. Thanks!

A max795 or st795 is the power monitor chip. Why use doom? Stunt race makes it oh so easy. Just do the rom swap.

Thanks for the info! Greatly appreciate it ^_^.

As I recall from the research I've performed on this matter, the reason I settled for the doom pcb with a jumpered battery backup was the sheer amount of concerns I found surrounding the GSU-1 FX chip's efficacy to run at the higher frequency (21mhz as opposed to 10.5), and the supposition that it can only support 8 mbit games, whereas the GSU-2 in Doom (and a few other carts) is said to handle 16mbit games.

I also found an excel spreadsheet online which, while not exceedingly technical, does back up that Star Fox 2 is/was the 16mbit type. Of course, there's something to be said concerning "the things one finds online;" all I'm getting at is why I've made the assumption that doom is the best route to go.

If nothing else, it's also found in nigh every game store near where I live, and averages about 10 bucks. Far as I know, stunt race is a bit more expensive.

Of course, I am open to better suggestions/being set straight. Could be everything I've just written is a lot of bunk; for all I know, Vortex could work, given the right amount of Jerry rigging. Dunno, though; never seen the pcb info for that one.

star fox 2 is an 8mbit game and there's no slowdown or other implications if you use a GSU-1 instead, see: http://www.assemblergames.com/forums/showthread.php?36459-SuperFX-overclocking-mod-just-a-fake&p=549131&viewfull=1#post549131


you can find stunt race for 10 usd on ebay's "buy it now" (you can probably get it cheaper on action though)

Ah. Well then; "the more you know," right? ^_^. Guess I'll investigate that option instead. Seems much less prone to catastrophic failure.

Thanks for the info, kind sirs/madams; I shall follow this up if/when I am either met with success, or enough failure as to make the cost effectiveness of this procedure highly suspect.