I'm searching for any solution to use Z80 with SCPU's 65816. Really when is SCPU turned on get control over all. Yes, possible is to use overclock 8502 to ~1,3MHz but really is not possible to switch to Z80 mode.
Like dream GO128 is my dream turning off SCPU by software method.
I'm thinking about all, for example here's decription of ABORTB (I got is from Richard Conrad and I'm thankful):
The Abort (ABORTB) negative pulse active input is used to abort instructions (usually due to an Address Bus condition).
A negative transition will inhibit modification of any internal register during the current instruction.
Upon completion of this instruction, an interrupt sequence is initiated.
The location of the aborted OpCode is stored as the return address in stack memory.
The Abort vector address is 00FFF8,9 (Emulation mode) or 00FFE8,9 (Native mode).
Note that ABORTB is a pulse-sensitive signal; i.e., an abort will occur whenever there is a negative pulse (or level) on the ABORTB
pin during a PHI2 clock.
Have anybody any idea? Of course if is used reset, then SCPU init starts so by software is needed to make active real 8502 or any dissapearing control over all by SCPU...