The 8051 architecture provides many functions (central processing unit (CPU), random-access memory (RAM),
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Intel's first MCS-51 microcontroller was the 8051, with 4 KB ROM and 128 byte RAM. Variants starting with 87 have a user programmable EPROM, sometimes UV erasable. Variants with a C as the third character a… See more

The MCS-51 has four distinct types of memory: internal RAM, special function registers, program memory, and external data memory. To access these efficiently, some compilers utilize as many as 7 types of memory … See more

The only register on an 8051 that is not memory-mapped is the 16-bit program counter (PC). This specifies the address of the next instruction to execute. Relative branch instructions supply an 8-bit signed offset whic… See more

The microarchitecture of the Intel MCS8051 is proprietary, but published features suggest how it works. It is a multi-cycle processor. The MCS8051 used 12 clock cycles for most instructions. Many instruction… See more

Instructions are all 1 to 3 bytes long, consisting of an initial opcode byte, followed by up to 2 bytes of operands.
1⁄4 of the opcode bytes, x0–x3, are used for irregular opcodes.
3⁄4 of the o… See more