nesdev.org

I decided that for the initial model, I'd just not use the SRAMs on my board at all, since the original concept didn't involve those anyway. That aspect evolved out of my "just one more little thing" tendency, which added unnecessary complexity considering I've never made such a thing befo...

Just out of pure curiosity, if a person added in a second 7805 regulator, tying it into the 9v coming from the adapter (wiring it right off the legs of the 7805 in the NES already, since they're easy to get to), would that allow for another few hundred more milliamps for other use? I mean the NES wa...

Using my own supply was a consideration if absolutely necessary, but obviously I'd rather try to avoid it. I can't find the datasheet for the old SRAMs I'm using; they're cache ones from some 486 motherboard. UM61M256K-15. The closest I found was someone in a newsgroup linking to a different model b...

I remember from my PIC projects that my PC's serial port wouldn't work with standard TTL voltages, though my laptop would. So seeing as how most of my work is on my desktop machine (since it's the better of the two), I'd probably want a MAX-232 in the mix if I were going to use serial. It's certainl...

I once did a serial connection with a PIC by using manual timing, but it wasn't the most reliable. I don't think I know enough about the timings of the instructions per clock and such of the 6502 to try and do it, though. If my math is right, 1.7897725mhz of the cpu should mean about 558ns per clock...

This isn't so much a question, but I thought I'd put it here since it's all related, and someone might find it interesting. For my project here, I knew I was going to need a way to transfer code to the NES often for debugging purposes, since it'll be nearly impossible to test things in an emulator d...

Well true, though I mostly just meant that the only way for it to determine the upper and lower 32K was by using O2 and PRG /CE, since it doesn't have a pure A15 available for the true way of determining. As far as I understand it, you can't base just an inverted PRG /CE on whether it's the lower 32...

I've got all that worked out now, I believe. I'm curious though; the only way for a cartridge to determine whether an attempt to access WRAM has taken place is by using O2 and PRG /CE, right? I won't go into another drawn-out explanation of what I want to do and the other ways I'm working around it,...

He'd probably be better off tying to the address lines like normal and just doubling up the rom image on the chip, then he can use the same board for other bigger roms in the future.

Yeah it'd prolly be easier if I could just show what all I've scribbled on paper, but I don't have access to a scanner as of the moment. And it's probably about like programming, anyway; even with something to look at, it can be hard to tell what somebody elses stuff is doing sometimes, if it's very...

You got it.

Normal AC adapters are unregulated and run at higher voltages unless they have the load applied to them that they were designed for. A volt meter obviously doesn't supply much load, so you see way more than the rated value. The power gets regulated once inside the NES/Famicom to keep a constant volt...

Hmm, I had a thought, which possibly messes up my idea. While doing the resistor on VRAM /CE might keep it pulled low on no cartridge, and leave it alone when a cart is in it, I realized that I might have a problem if there's a cartridge inserted, but that particular one doesn't use the NES internal...

I should mention that this particular project will be seperate from a cartridge; it'll still allow normal carts to be played. Of course, I've never designed such a hardware project before, so one can only hope my designing will be correct! I could probably go look at how folks have done certain simi...

For what I'm working on I've got some questions, and might possibly have others as I come to'em, so I figure I'll just use this one topic as they come along instead of making a bunch for different things. Firstly, can anyone see any issue with putting a pulldown resistor of say 10k on the VRAM /CE, ...