Aaron's Blog

nasm -f coff first.asmgcc -c driver.cgcc -o first first.o driver.c asm_io.o

instruction: CMPcomparing by subtractionfor unsigned numbers:  2 bits in the FLAGS register      ZF      CF  =    1       0  >    0       0  for signed numbers:  3 bits in the FLAGS regist

环境变量设置：Right-click My Computer, select Properties. Select the Advanced tab, then the Environment Variables button. Edit the Path (or PATH, whichever exists) system variable to include C:/DJGPP/BIN a

Decreasing size of dataFor unsigned numbers:  All the bits being removed must be 0 !For signed numbers:  Bits being removed must be all 1s or 0s and the first bit not being removed must have the

Two of the bits in the FLAGS register that add and sub instructions set are overflow and carry flag:Overflow flag:  Set for signed arithmetic when the ture result is too big to fit into the destinat

ADCoperand1 = operand1 + carry flag + operand2 SBBoperand1 = operand1 - carry flag - operand2