Intel 8051 manual Logic Operations, External Data Memory Move Operations

8051 Architectural Specification and Functional Description

REGISTER	DIRECT
R7-RO	Data

REGISTER

A

REGISTER

A

REGISTER·INDIRECT	REGISTER-INDIRECT
@R1,@RO	@DP
(EXT DATA 0-255)	(EXT DATA 0-64K)

REGISTER-INDIRECT

@R1,@RO

Figure 2.18. External Data Memory Move Operations

can be moved to any of these locations. Of particular interest is the Direct Address to Direct Address move which permits the value in a port to be moved to the Internal Data RAM without using any RB registers or the accumulator. The Data Pointer register can be loaded with a double-byte immediate value. Also, the 8051's Boolean Processor can move any Direct Addressed bit to or from the carry flag.

The A register can be exchanged with a register in the selected Register Bank, with a Register-Indirect Addressed byte in the Internal Data RAM or with a Direct Addressed byte in the Internal Data RAM or Special Function Reg- ister. The least significant nibble of the A registt;r can also be exchanged with the least significant nibble of a Register- Indirect Addressed byte in the Internal Data RAM. The exchange operation is shown in Figure 2.20

Figure 2.20. Internal Data Memory Exchange Operations

2.5.2 Logic Operations

The 8051 permits the logic operations of and, or, and exlusive-or to be performed on the A register by a second operand which can be immediate value, a register in the selected Register Bank, a Register-Indirect Addressed byte of Internal Data RAM ora Direct Addressed byte of Internal Data RAM or Special Function Register. In addition, these logic operations can be performed on a Direct Addressed byte of the Internal Data RAM or Special Function Register using the A register as the second operand. Also, use of Immediate Addressing with Direct Addressing permits these logic operations to set, clear or complement any bit anywhere in the Internal Data RAM or Special Function Registers without

REGISTER	DIRECT	REGISTER
C	Data	DPTR

16

REGISTER

R7-RO

DIRECT	IMMEDIATE
Data	# data

REGISTER	REGISTER-INDIRECT	REGISTER-INDIRECT
A	@R1,@RO	@SP

Figure 2.19. Internal Data Memory Move Operations

AFN-01488A-19

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