Electronic Circuits and Tutorials
8051/8052 Microcontroller Tutorial

8051 / 8052 Microcontroller Instruction Set :
AJMP - Absolute Jump

Operation: AJMP
Function: Absolute Jump Within 2K Block
Syntax: AJMP code address


Instructions OpCode Bytes Cycles Flags
AJMP page0 0x01 2 2 None
AJMP page1 0x21 2 2 None
AJMP page2 0x41 2 2 None
AJMP page3 0x61 2 2 None
AJMP page4 0x81 2 2 None
AJMP page5 0xA1 2 2 None
AJMP page6 0xC1 2 2 None
AJMP page7 0xE1 2 2 None


Description: AJMP unconditionally jumps to the indicated code address. The new value for the Program Counter is calculated by replacing the least-significant-byte of the Program Counter with the second byte of the AJMP instruction, and replacing bits 0-2 of the most-significant-byte of the Program Counter with 3 bits that indicate the page of the byte following the AJMP instruction. Bits 3-7 of the most-significant-byte of the Program Counter remain unchanged.

Since only 11 bits of the Program Counter are affected by AJMP, jumps may only be made to code located within the same 2k block as the first byte that follows AJMP.

See Also: LJMP, SJMP, Instruction Set

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