What does the z80 do when it crashes?

Is this like a joke?

What does the z80 do when it crashes?

It depends on how it crashes.  I would say it just resets to start at $4000 on page 7F, just like booting.  TIOS may have a flag somewhere that gets set every time the OS starts, and if RAM is cleared, the flag is automatically reset, indicating to TIOS that RAM was reset.

Ahh. Oops. But now I'm curious, what DOES happen? RAM clear? Calc turns off? Do you just remove the batteries for 15 minutes?

You usually don't have to keep batteries out, that's only for rare cases.

Actually in that case it might be a freeze. When the calculator crashes, the user sees it eventually turn OFF, kinda, then when truning it ON again it says RAM Cleared. Some bad ASM code could cause the calc to freeze like you described and never get to the reset code (or whatever it is), so a battery pull is required.

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?

Yeah he really wants to know what technical stuff does the calc do, such as what ASM code is executed and how the hardware operates.

Here's what I learned from that crash tutorial:

- When the RAM clears (probably because a certain address reads zero), the calculator runs the boot certificate code, which is a bit of code that all calculators have, and cannot be modified. This code tells it to boot the OS. (If you hold down DEL while replacing the battery, it will not boot the OS and will instead accept a new one from link transfer)
- When the OS boots, it goes through your archive and looks for archived variables, putting them into the VAT for access later. (If you hold down CLEAR while replacing the battery, it will skip this step, and it will appear as if there are no variables in archive)
- Once it has gone through your archive, it initializes all of the RAM variables and shows you the RAM Cleared screen.

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.