4位中央处理器仿真系统

Problem Machine A 4 bit CPU simulation for Android... Registers PC - 4Bit Program Counter A - 4Bit accumulator register A" - 4Bit shadow register Flags Z - Zero Flag IO Ports IN - 4Bit input port OUT - 4Bit output port Opcodes 0000 - SHL - Shift Left ( A = (A << 1) ) 0001 - SHR - Shift Right ( A = (A >> 1) ) 0010 - IN - ( A = IN ) 0011 - OUT - ( OUT = A ) 0100 - INC - Increment A ( if(A == 0){Z = 1}; else {Z = 0}); 0101 - DEC - Decrement A ( if(A == 0){Z = 1}; else {Z = 0}); 0110 - ZERO - Zero A (Z = 1) 0111 - SWAP - Swap the accumulator and shadow register ( Z == Z ) Jumps Jumps unconditional 10 00 - JMPZ - PC = 0 10 01 - JMPA - PC = A 10 10 - JMPO - PC = PC - 1