Things to screw with on the SNES / Technical Stuff

[XBrav]

Please forward me to the proper area if this question does not suit the section.

I have a fisrt generation SNES (separate APU unit ) that works perfectly fine. My case was screwed on it, leaving me with the board and everything else in tact.

Number one, I know these units are too bulky to justify a portable. That was not my intentions with this unit.

Number two, I have done some research on the net, and I ain't just looking for basic schematics.

I do a lot of electrical work with binary logic and video signals. Does anybody know how everything in the SNES works together? I have many ideas of how to work with the SNES, but wish there was better documentation on it.

So here are a few of the questions I was hoping someone could help answer:

1) Does the SNES first output digital data for video signals, then convert to composite via a DAC? Or does the CPU (or PPU-1 and PPU-2, depending on the function order) output a flat analog signal straight from the CPU?

2) How exactly does the SNES APU work? If it is based on MIDI-formatted data, would it then not be difficult to write a sequencer with a PIC or equivilent?

3) If the SNES cartridge pins act as a large BUS, cannot you build a simple gameshark by preventing access to certain memory locations? Kinda like using the lockout chip method?
- Basically this idea involves a series of logic gates, or you could write an app for a PIC that controls the data to be written into onboard RAM)

These are only a few of my ideas. Other than those, do any of you have any ideas how to screw with the snes?

[bazz]

I was just scoping the forum but I don't have much time, all I can tell you is that the APU does not process midi data. It is sample-based and the spc700 tells the dsp what to do. I remember some choppy midi->snes converter called mss(?) was written by Grog and some dudes, you could look that up but I don't know if that will help you.

Good luck with your ideas

[Life of Brian]

I'm afraid all of that is a bit more advanced than what most of us are familiar with. Perhaps you could teach us a thing or two about the inner workings of the SNES?

[XBrav]

I'm afraid all of that is a bit more advanced than what most of us are familiar with. Perhaps you could teach us a thing or two about the inner workings of the SNES?

Haha I would but frankly, this is the first time I've opened one. I mean, I can tell ya this much:

System has an APU which may be onboard or removable depending on your version

There are 2 picture processing units (like graphics cards). I'd assume one is for sprites and the other for background and foreground stuff.

There are many places on the board labelled for capacitors but are left empty. They were even tinned to add them on. Yet the unit still operates.

Even the SNES can handle S-Video. When you use a gamecube cable with it, it looks amazing!

There is one 7805 regulator on the board, with a MASSIVE heat sink (that metal sheet that covers half the board). The snes must work in the digital limitations world (0-5V)

Pins 50-53 and pin 26 of the SNES cartridge actually go directly into pins 11-15 of the APU

There are holes in the motherboard directly in the middle of all the main ICs on the mainboard. Looks like it was meant to be removed...

The SNES has one S-WRAM, and one CPU. However, mine is stamped "CPU A", maybe suggesting a future upgrade.

Other than a few capacitors or resistors (can't get at em right now to look), the SNES controller faceplate is literally an adapter from the 2 ports to an 11 pin cable.


Well that's all I got for now.