Force break "BRK" is implied not immediate addressing mode

[jchristof]

{ "BRK", &a::BRK, &a::IMM, 7 } should be { "BRK", &a::BRK, &a::IMP, 7 }

[mebusy]

This has troubled me as well. In fact PC was incremented in 3 places: after reading BRK byte, IMM addressing, BRK() subroutine. It should not the expected behavior.

BRK causes a non-maskable interrupt and increments the program counter by one. Therefore an RTI will go to the address of the BRK +2 so that BRK may be used to replace a two-byte instruction for debugging and the subsequent RTI will be correct.