Here's a little test using the length of time you hold down the start button as a random seed. This could be suitable for a title screen where you press start to begin the game.
http://rainwarrior.ca/projects/nes/buttonlen.zip
I just enter a polling loop when start is held, incrementing it each time. When you release, the 8-bit loop counter is displayed on the screen. ca65 source is included if you want more details.
Actually works pretty well. On emulators I don't think you really get sub-frame timing on the input (I find the number 47 comes up a lot on FCEUX), but on the NES it seems completely random, and even on emulators it's not bad at all. Dwedit mentioned a possible need to debounce when doing this, but I don't seem to have any problem with that on my NES.
Fun fact: the GBA port of Final Fantasy IV seeds its random number generator by number of seconds spent on the title screen. I abused this at one point to finally get a pink tail. (My avatar is related.)
http://rainwarrior.ca/projects/nes/buttonlen.zip
I just enter a polling loop when start is held, incrementing it each time. When you release, the 8-bit loop counter is displayed on the screen. ca65 source is included if you want more details.
Actually works pretty well. On emulators I don't think you really get sub-frame timing on the input (I find the number 47 comes up a lot on FCEUX), but on the NES it seems completely random, and even on emulators it's not bad at all. Dwedit mentioned a possible need to debounce when doing this, but I don't seem to have any problem with that on my NES.
Fun fact: the GBA port of Final Fantasy IV seeds its random number generator by number of seconds spent on the title screen. I abused this at one point to finally get a pink tail. (My avatar is related.)