System05 - VHDL 6805 Clone

As a matter of  stepping stone to the holy grail of designing a MC6809 to run Flex, I have attempted to code a 6805. The 6805 only has one 8 bit accumulator and one 8 bit index register. Unlike the Micro8 design it has a 5 bit stack pointer in the base page, sitting at $007F and working down to $0060. Note that as of  6:53am on  September 19th 2002 it is totally untested and is very unlikely to work. It does compile under ISE Web Pack 4.2, although generates a few warnings. I have not implemented a proper timer module, and I have to change the memory map for the ROM and I/O. Also the ROM code is probably totally wrong.

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