Re: 65816 abort line on the AppleIIgs

[Matthew Montchalin <mmontcha@OregonVOS.net>]

On 31 Oct 2002, Michael J. Mahon wrote:
|>Can you be more explicit?  If ror <address> involves a read of a
|>specified memory address, and then rotate some internal register
|>+carry, before write-back, are you suggesting that it makes no
|>difference how far into the execution we go, if the abort occurs
|>prior to the write-back, the whole instruction is executed over
|>again, after we get back from the Abort handler?
|
|I said on the _first_ reference to the memory address.  So the
|abort would be asserted when the location was read, and before
|any data was returned.

What about memory mapped I/O?

|If the memory is not present, there can be no valid data.  The
|important part is that no internal register is updated by the
|aborted instruction, so that it can be re-executed later.