What is the difference between carry flag and auxiliary flag?
From what I seem to know by now is that the Carry Flag is used when you try, let’s say, 255+9 when you only have 8 bits for data, The Auxiliary Flag is the same, but only for the 4 last bits?? And The Overflow is used when you have 7 bits for the binary number and the 8(left-most ) is used for the sign???
Which of the following flag is set when result is positive or negative?
Sign Flag (SF) – set to 1 when result is negative. When result is positive it is set to 0. Actually this flag take the value of the most significant bit. Overflow Flag (OF) – set to 1 when there is a signed overflow.
What is the use of auxiliary carry flag in 8085?
Auxiliary carry flag (Ac): Now let us consider the addition of any two 8-bit (2-hex digit) numbers, a carry may be generated when we add the LS hex digits of the two numbers. Such a carry is called intermediate carry also known as half carry, or auxiliary carry (AC).
How to describe subtraction with carry in Intel 8080?
The subtraction-with-borrow style, used in Intel main CPU dynasty (8080, 8086 and so on), PDP-11 and many other computers (despite some of them call it as subtraction with carry), can be described as follows: Let M is minuend, S is subtrahend, B is previous borrow flag (in Carry bit).
How to set the Auxiliary flag on the Intel 8080?
The 8085 logical AND instructions always set the auxiliary flag ON. The 8080 logical AND instructions set the flag to reflect the logical OR of bit 3 of the values involved in the AND operation. OR and XOR operations clear the auxiliary flag on the 8080, which is why it appears in the corresponding opcode descriptions.
When does sub B set the Auxiliary Carry Flag?
Does SUB B on Intel 8080 set the auxiliary carry flag when the accumulator and the B register are 1 and 0, respectively? On Z80, which was designed to be a backward-compatible, albeit not fully, extension to 8080, the half-carry flag is defined so that it gets set if subtraction results in a borrow from bit 4 (Z80 CPU User Manual, p. 68).
When to set the carry flag in 8080?
Does this mean it simply flips the carry flag that would be generated by addition as described above? (I.e. sets it when the result does not overflow i.e. less than or equal to 255?) The 8080 sets the carry flag when the unsigned value subtracted is greater than the unsigned value it is subtracted from.
https://www.youtube.com/watch?v=PhjLE0HodEw