it seems weird that both boards would have the identical problem.
Not really, since most of the address lines are actually shared between both displays. That means that a short on one side will affect both screens. 🙁
Shoot, so what you’re saying is only one of my displays is most likely bad? I don’t see any other problems with the image except for those evenly-spaced horizontal lines in both displays. If one of my displays is bad, could I just disconnect it and the other display should appear normal? At least that way I could narrow down my problem to one display.
Yes… unhook one of them to narrow down the bad display. If hooking one of them up causes them both to have lines, you’ve got a short on that display.
Did you try that exact code? I just did a search on that error and came across this: http://bytes.com/topic/c/answers/221491-constants-not-constant , where someone tried to use a const for the size of the array… which won’t work. You’d need to use #define for the size.
should work:
ExampleTypedef ExampleArray[5];
should work:
#define arraysz 5
ExampleTypedef ExampleArray[arraysz];
shouldn’t work:
const int arraysz=5;
ExampleTypedef ExampleArray[arraysz];
Yep… that’s pretty much it, though not all instructions are 32 bit. Some instructions are 16, some are 32, and since there’s a 16 bit bus, it just reads 16 bits at a time and either executes the instruction, or knows that it’s 32 bits and reads the last half of the instruction, then executes that.
Well… a CPU keeps executing whatever is handed to it, and keeps incrementing the PC… so that’s what’ll happen. Odds are it’ll just keep running away until it hits something that throws it off… like maybe a HALT command.
If you want to keep feeding it something, I’d either feed JMP $FFFFFFF0, so it keeps going back to the reset vector, or BR -2 to keep the PC from moving.
Just because there’s no monetary loss, it doesn’t make it legal. Of course companies are typically worried more about money than legalities, so if you start up a page selling bootleg VB games and a page selling bootleg Wii games… the Wii one will get shut down quickly, the VB one may or may not at all.
Heh… I think it’s a bad idea, and I don’t see why it’s necessary. Your resistor will have to be very low resistance and high power. I know the 5V rail can supply a steady 5V @ >500mA. To drag that down to brownout level, you’d need to draw probably ~2A. I’d guess the power supply would detect the power bad and reset the CPU before the CPU actually resets from low voltage (I’ve run the VB at 3.3V and the CPU works fine).
So, 2A on a 5V rail is 2.5 ohms, and 10W. Of course the voltage would drop, so it’d be less than 10W because it wouldn’t actually draw 2A… but you get the idea. And I’m sure that’s not good to repeatedly stress the regulator like that.
If you’re talking about just using a high value resistor between +5V and GND, that’ll just be a pointless heater 😉 . You’ll have to draw at least more than 500mA through the resistor.
There’s an interrupt line available on the cart edge, but to use it, you’d need to make sure it’s not already handled. If you modified the ROM when burning, you could use the EXT interrupt to jump to the reset vector, since the EXT area is basically unused. I have a VB that I modified with a switch there, and use it basically as a reset switch for homebrew.
>What does the VB do right after you turn on the power? There seems to be a delay between when I turn the power on and when I actually see the first game screen, so the CPU must run some self-initializing code before it reads data from the flash chip on the cartridge, correct? Does anyone know how the VB accesses the program instructions from the cartridge memory and how long it takes between power-on and the first instruction read?
After it comes out of reset, it begins executing the reset vector. Of course some games have an initialization, but that’s completely up to the game. You’ll notice delays in seeing anything, which is caused by the displays getting in sync. But that has nothing to do with the actual program. If you stop the mirrors during the game, the displays will also turn off. I believe that’s all controlled internally in the VPU.
>Also, what does the VB do when it tries to read data from a cartridge and there is nothing in the cartridge memory?
It’ll just try to execute whatever it reads… which like RunnerPack said, probably all high, but possibly something else… but nothing useful.
>Is the PSRAM you are referring to part of the CPU architecture or are you referring to the RAM on a game cartridge?
PSRAM is Pseudo SRAM, which is the Work RAM internal to the VB (RAM used for programs and stuff).
>What is the NVC? I haven’t read the programming manual/wiki for a while and I don’t remember what that stands for. I’m guessing it has something to do with the fetch/decode of the CPU pipeline?
Heh, you could say that… it’s the CPU 😉 .
>So there is a reset line on the voltage regulator, but is there any other way to reset the system? Every CPU architecture I can think of has a way of “soft” resetting the CPU without losing power.
Yeah, there’s a reset line, which is controlled by (at least) the power good pin on the regulator. Like I mentioned in the other thread, you can reset by jumping to the reset vector.
Vaughanabe13 wrote:
For those of you expert VB programmers, is it possible to reset the VB from a software command? If not, is there any way to reset the VB without turning off the power switch? I know some CPU’s will reset if you make a brief connection between +5V power and ground – will that trick work with the VB?
Going along with this, I heard through the grape vine that it is possible to hotswap cartridges while the game is on. Anyone have information on that?
At reset, the VB starts executing from the reset vector (0xFFFFFFF0), so simply jumping to address 0xFFFFFFF0 would reset, assuming you just want a program reset, not necessarily a CPU reset. Heh, shorting +5V to GND will certainly reset the processor, but I recommend against it, since it could also blow the regulator 😛 . You might as well use the power switch because you’re killing the output from the regulator.
Hot swapping is possible, though of course your program has to be running from RAM, and you have to make sure there’s no glitch on the address/data lines, since it’s shared with the rest of the system. IIRC, hot swapping carts with the backup battery doesn’t seem possible without modification, because one of the pins (pin 9 maybe?) causes the system to reset. Lifting one of the pins fixes that… I think pin 9, which must have caused an interrupt, resetting the program (I’d have to look back at my notes for all the specifics).
BTW, I got your PM and started to reply, but I’ll just fill in what hasn’t been answered already in your posts… probably better that the information is posted publicly anyway 🙂 .
No… that’s the expendable fuel to make it work. Is filling your car’s gas tank considered maintenance? But, everyone should own an AC adapter anyway, so that shouldn’t be a question anyway 😉 .
Vaughanabe13 wrote:
What kind of screwdriver and file did you use? I haven’t been able to make a dent in my flathead with my dremel. This is just a cheap screwdriver too.
Really??? Are you using a cutoff wheel to make the notch? Before ruining a perfectly good screwdriver though, make sure it’ll fit inside the VB holes (you may want to cut off the edges if it has a taper on the sides), and that the tip is large enough to span the screw head.
