Cho đoạn mã lệnh sau:

CJNE A, #30H, TIEP

TIEP: JNC SKIP

Ta có thể thay thế đoạn mã lệnh trên bằng:

The original code block has the following structure: CJNE A, #30H, TIEP TIEP: JNC SKIP The instruction "CJNE A, #30H, TIEP" compares the value of register A with the value 30H. If A is not equal to 30H, the program jumps to the label TIEP. If A is equal to 30H, the program executes the next instruction immediately after CJNE. The instruction "TIEP: JNC SKIP" checks the Carry flag (C). If the Carry flag is not set (C=0), the program jumps to the label SKIP. If the Carry flag is set (C=1), the program executes the next instruction. To replace the above code, we need to find an equivalent code block that performs the same function. * **Option A: CJNE A, #30H, $ JNC SKIP** * Using the current address ($) as a jump label for CJNE is illogical because it doesn't actually jump to a specific location but only executes the next instruction. After CJNE, it will go to JNC SKIP. This option is not equivalent because it always executes JNC SKIP if A!=30H, which is not consistent with the original logic. * **Option B: CJNE A, #30H, $+3 JNC SKIP** * `$+3` means jumping to the current address plus 3 bytes. If the `JNC SKIP` instruction is compiled into 2 or 3 bytes, jumping to $+3$ might skip the `JNC SKIP` instruction or jump into the middle of the instruction, causing an error. This code is not equivalent. * **Option C: CJNE A, #30H, $-3 JNC SKIP** * Similarly, $-3$ means jumping to the current address minus 3 bytes. This can lead to jumping back into the previous instruction or into the middle of the instruction, causing unwanted errors. This code is not equivalent. * **Option D: CJNE A, #30H, SKIP TIEP: JNC SKIP** * This option is incorrect because the label TIEP is placed after the CJNE instruction and before the JNC SKIP instruction, which is syntactically invalid in most compilers/assemblers. CJNE cannot jump to SKIP. However, none of the options above are completely equivalent and accurate in function compared to the original code. Therefore, there is no correct answer in this case. It's possible the question lacks a valid replacement. Based on analysis, no replacement is fully equivalent.