Re: 6510 CPU extensions

From: Andre Fachat (
Date: 2002-05-01 20:50:23

  • Next message: William Levak: "Re: Using a 27C512 instead of a 82S100 PLA"
    If you want to be flexible, maybe you want to have a look at my CS/A65
    machine. The CPU card has a 74LS610, which maps addresses:
    The address space is split into 16 blocks with 4k each and the 74LS610
    provides 16 registers with 8 bits (actually 9, but the last bit has
    to be set separately and provides a write-protect bit for the page)
    that replace the upper 4 address bits:
    	A12-15  --> index in register file --> A12-19
    So each of the 16 4k blocks can be mapped from a 1M address space
    Maybe you also want to include this in your CPU...
    Andre wrote:
    > >What about the 6509? That is a 6502 with the difference that it has
    > >4 more address lines. The output values of the 4 address bits is
    > >determined by the values of register 0 and 1. register 1 is used for
    > >the data load and store operations in the lda (),y and sta (),y
    > >opcodes and reg. 0 otherwise. (r0/r1 maybe vice versa, but in principle
    > >that is it).
    > This chip is indeed and interesting one. The theme could be extended to
    > include a full 8-bit paging offset, allowing 16MB rather than 1MB access.
    > For the setting of the register one of the illegal fatal codes could be used
    > as the operand.
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