If the 8086 adds 9679H and 6987H, Specify the contents of the Accumulator and the status of the SF, ZF, CF flag.
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Answer:
As you may see there are 16 bits in this register, each bit is called a flag and can take a value of 1 or 0.
Carry Flag (CF) - this flag is set to 1 when there is an unsigned overflow. For example when you add bytes 255 + 1 (result is not in range 0...255). When there is no overflow this flag is set to 0.
Zero Flag (ZF) - set to 1 when result is zero. For none zero result this flag is set to 0.
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. For example, when you add bytes 100 + 50 (result is not in range -128...127).
Parity Flag (PF) - this flag is set to 1 when there is even number of one bits in result, and to 0 when there is odd number of one bits. Even if result is a word only 8 low bits are analyzed!
Auxiliary Flag (AF) - set to 1 when there is an unsigned overflow for low nibble (4 bits).
Interrupt enable Flag (IF) - when this flag is set to 1 CPU reacts to interrupts from external devices.
Direction Flag (DF) - this flag is used by some instructions to process data chains, when this flag is set to 0 - the processing is done forward, when this flag is set to 1 the processing is done