When something goes wrong, such as execution on a restricted page, what actually happens?

I'm just curious, for error handling in KnightOS.  I'm pretty sure that is what happens.

There's this tutorial that someone wrote on how to deal with crashes. I can't remember where it is, but it was really sophisticated, and went into everything from running out of batteries to using Calcsys. Could someone please post that link?

That was ClrHome methinks
Now I'm starting to get curious as well...
I'm kind of speculating here, but I'll guess the OS detects something wrong, goes "uh oh", resets the RAM, sets some flag to say "RAM cleared" on reboot and to finish turns off the calc.
idk really tho

I don't know much more (much less the super techincal details of all of this) but I know that some people do know. One such person is Benjamin Moody, the person who made The Impossible Game and TI-Boy SE. His app, zStart, can run on RAM clear, which means that all of your defaults are automatically restored after a crash. It works because part of the OS is modified to call that code.

Actually, thepenguin77, aka Brian Coventry made the Impossible Game and zStart.
FloppusMaximus, aka Benjamin Moody made Mimas.
And calc84maniac, aka Brendan Fletcher made TI-Boy SE

In an asm program the OS is only present when you run a bcall or an interrupt is toggled. When you try to execute code from a bad page, a hardware exception is enabled that resets the cpu. I believe there is a pin on the z80 that triggers a reset when it is set by an external device.

What happens during a crash? The CPU executes instructions that don't make sense. For example, it places garbage on the stack, jumps into the middle of a routine, and then tries to return. The top entry on the stack is garbage, so it jumps to a random location in memory. If the location is in the 0C000h+ range, the hardware simply resets the CPU. If the top location is 0000h, it reboots. Often, the CPU will start executing data as code, placing the CPU into a random state. It might start overwriting RAM with garbage. Either way, the CPU eventually finds its way into the 0C000h range and resets, or hits the reboot code itself. If the CPU doesn't, you might get a freeze.

Now the question is why so many people who are insane at Assembly, including Ben Ryves and those previously mentioned, all have names starting with the letter "B."

And Brandon Wilson ... what the? O.o

What happens during a crash? The CPU executes instructions that don't make sense. For example, it places garbage on the stack, jumps into the middle of a routine, and then tries to return. The top entry on the stack is garbage, so it jumps to a random location in memory. If the location is in the 0C000h+ range, the hardware simply resets the CPU. If the top location is 0000h, it reboots. Often, the CPU will start executing data as code, placing the CPU into a random state. It might start overwriting RAM with garbage. Either way, the CPU eventually finds its way into the 0C000h range and resets, or hits the reboot code itself. If the CPU doesn't, you might get a freeze.

Ohh, so that's why it has the $C000+ protection? All crashes must find their way into the fourth bank, or the calc freezes? I guess the 8811-byte limit does have some use after all.

Quote from: Compynerd255 on March 24, 2011, 09:28:22 pm

There's this tutorial that someone wrote on how to deal with crashes. I can't remember where it is, but it was really sophisticated, and went into everything from running out of batteries to using Calcsys. Could someone please post that link?

That was ClrHome methinks

I don't think it's too useful for this topic, but in case anyone's wondering, it's here (or here or here or here ).

Naw, the $C000+ limit is for money-sucking purposes.  It used to cost money to make apps, and that was the only way to execute more code.

Lol, funny.  I still like the idea about having a flag that gets reset when a ram clear happens to test for ram clears.  Although two things:
1) Should this be moved to KOS, or left here as it's not necessarily KOS related.
2) Does this happen if you jump to C000h+?