In the 8085 microprocessor, if SP = 3FFFH and memory contains: 3FFEH = 20H, 3FFFH = 20H, 4000H = 10H, 4001H = 10H. After executing POP H, what will be the contents of HL?
1020H
This question tests how the stack operates in the 8085 microprocessor. The stack is a region of read/write memory that grows toward lower addresses, and the Stack Pointer (SP) always holds the address of the top of the stack (the last byte pushed). Data is stored in the 8085's usual little-endian order for register pairs: the lower-order byte occupies the lower address and the higher-order byte the next higher address.
The POP H instruction transfers two bytes from the top of the stack into the HL register pair and then adjusts SP. Its exact micro-sequence is:
Combining the two bytes with H as the most-significant byte: HL = H:L = 10H:20H = 1020H. This is the correct answer, and SP finishes at 4001H.
Why the others are wrong:
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