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PostPosted: Wed Sep 26, 2012 9:53 pm 
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Joined: Thu Dec 11, 2008 1:28 pm
Posts: 10971
Location: England
Marc Cleave has been designing and building an 8-bit CPU from TTL. Here are the specs on github.

He's got links to some video diaries and overall notes on his website.

He's using wirewrap, with ordinary sockets and posts so the wirewrap is on the top side:
Image(click to embiggen)

It's not a 6502, but it does have 8 bit registers and a 16bit address bus. The opcodes are nibbly, so he can address 16 registers with some two-operand instructions and still use a maximum of 3 bytes with a regular decode. Here are his features:
    8 bit data bus
    16 8 bit registers, mapped to them are the program counter and stack pointer
    16 bit stack pointer(64k stack)
    16 bit program counter
    64k addressable memory
    Capable of 10 8bit arithmetic functions
    Various addressing modes(Immediate, Indirect, Index, Register)
    Memory mapped I/O


Last edited by BigEd on Tue Oct 02, 2012 6:07 pm, edited 1 time in total.

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PostPosted: Tue Oct 02, 2012 1:05 pm 
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Joined: Wed Sep 19, 2012 6:19 pm
Posts: 122
Location: England
That's truly astounding. It's not the first project of this kind but anyone who builds a processor deserves my uttermost respect.


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