RE: 6510 CPU extensions

From: Gideon Zweijtzer (
Date: 2002-04-22 10:10:25

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    |> Last weekend I implemented an extra feature to the 6510 FPGA. It is now
    |> possible to connect the 6510 board to the PC by means of a serial cable.
    |> simple UART inside the CPU (that runs at a fixed bitrate of approx.
    |> gives access to the CPU-bus by means of a simple protocol. This hardware
    |> protocol-block is capable of generating internal DMA cycles. In other
    |> it is now possible to look in the C-64's memory or write into the C-64's
    |> memory while the C-64 is running.
    |In other words, you made the first in-circuit emulator for the C64,
    |right? ;-)
    Well, basically, yeah... you could put it that way. It started out just as a
    CPU though, I didn't have any intentions of making an ICE. At this point I
    can't use this UART to 'see' the internal registers, but this would be a
    small step. The sad part is that I would have to 'pull' these registers up
    to the top level of the design. This makes the VHDL code a bit sloppy.
    |BTW: what's your opinion, should it be possible to modify your design
    |for emulating a 8501 CPU (the heart of C16 / C116 / Plus/4)?
    Of course, that shouldn't be a problem; I think it is just a 6502 with some
    tiny modifications. I am planning to implement the 65816 as well, since
    there are many users.
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