http://www.amiga.org/forums/archive/index.php/t-35586.html
has some speculation about reset.
As it's all documented very well by commodore, most of the speculation is not only useless but is also wrong.
If it's not running at all then it will get reset straight away.
If it's running well and cleanup happens in less than 10 seconds then it will get reset as soon as cleanup finishes.
If the system is running well enough to respond to the reset warning, but not well enough to finish in 10 seconds then it will get reset anyway.
The A500 definately didn't have this. No idea why, they could have done it in the software of the mcu in the keyboard. It's possible that when the A500 keyboard was designed, they didn't realise that this functionality existed.
G Keyboard Interface / Reset Warning
About Reset Warning. ------------------- This feature is available on some A1000 and A2000 keyboards. You cannot rely on this feature for all Amigas.The keyboard has the additional task of resetting the computer on thecommand of the user. The user initiates Reset Warning by simultaneouslypressing the Ctrl key and the two Amiga keys.The keyboard responds to this input by syncing up any pending transmitoperations. The keyboard then sends a "reset warning" to the Amiga. Thisaction alerts the Amiga software to finish up any pending operations (suchas disk DMA) and prepare for reset.A specific sequence of operations ensure that the Amiga is in a statewhere it can respond to the reset warning. The keyboard sends two actual"reset warning" keycodes. The Amiga must handshake to the first code likeany normal keystroke, else the keyboard goes directly to Hard Reset . Onthe second "reset warning" code the Amiga must drive KDAT low within 250milliseconds, else the keyboard goes directly to Hard Reset . If allthe tests are passed, the Amiga has 10 full seconds to do emergencyprocessing. When the Amiga pulls KDAT high again, the keyboard finallyasserts hard reset .If the Amiga fails to pull KDAT high within 10 seconds, Hard Reset isasserted anyway.