(SOLVED) 41CL - DOUBLE HEPAX ACCESS and MMU CONFIG

[Monte Dalrymple]

(08-23-2019 10:05 PM)rprosperi Wrote:  

(08-23-2019 08:52 PM)Monte Dalrymple Wrote:  Any opcode that the CPU doesn't recognized is executed as a NOP as far as the CPU is concerned.

That makes sense (though I did not know that, so thx) but how does an a non-std OpCode, that is treated as NOP, let HEPAX do things like remap portions of code? Is it simply a marker for other code to recognize and then act upon?

Hardware outside the CPU watches for the opcode and acts when it sees it. I use the same technique with the WCMD instruction in the NEWT. Depending on the contents of one nibble in the C register (which is visible on the data bus) the logic sets the Turbo mode, reads or writes physical memory, enables or disables the MMU, etc. I would assume that logic in the Hepax module does something similar.