How many instructions in 8051

The second operand is the source, whereas the first one is the destination. This instruction uses various addressing modes to move data in the RAM space of the microcontroller. The microcontroller in most cases has an on-chip 4K flash memory, but due to its bit address bus, it can access 64k memory locations. Due to this reason, the can be interfaced with external memory using ports 0 and 2.

To access data in this external memory, the MOVX instruction is used. These registers are 8 bit wide and are bundled in groups of 8 forming four register banks. Stack operations can be used to place data into these registers in an efficient manner.

The PUSH operation is used to place data into the stack. When this command is given the value of address stored in the stack pointer is increased by one. After incrementing the address in the stack pointer, data is placed at that memory location. For example, when the is powered up, it holds the address 07H. When it receives the first PUSH instruction, the address is updated to 08H, and data is stored in that location.

The POP operation is used to extract data that is stored in the stack. This operation is the complete opposite of the PUSH operation. It extracts the data from the location which the stack pointer points to and then decreases the value of the SP by 1. We hope that reading this article has helped you to understand the data transfer instructions in the microcontroller. If you have any doubts feel free to ask them in the comments section below.

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Operation Mnemonics Description Register to register. Modern variants like the one we discussed in our post on architecture can execute an instruction that usually took the older version 12 clock cycles, in one clock cycle.

So, in the column on execution time below, you can divide the number of clock cycles by 12 to get the speeds of execution for modern variants of the Reference Guide microcontrollers. ADD A, "src-byte. Types of instructions in the microcontroller The instruction set of microcontroller can be divided into the following groups: Data transfer instructions. Arithmetic instructions. Logical Instructions Boolean. Program Control Instructions jumps. Bit manipulation instructions.

User: alciro. Memory structure in the microcontrollers 2. Internal data memory 2. Access memory directly and indirectly 2. Special function registers SFR for microcontrollers 3. Indexed 4. Types of instructions in the microcontroller 4. Program Control Instructions 4.

Assembler Programming 5. Stack or pile 5. POP 5. Subroutine or subroutine 6. Programming in C 6. Definition of symbols 7. Serial communications 7. The serial port UART 7. Example UART configuration 7.

The Op-Code part of the instruction contains the Mnemonic, which specifies the type of operation to be performed. All Mnemonics or the Opcode part of the instruction are of One Byte size. Coming to the Operand part of the instruction, it defines the data being processed by the instructions.

The operand can be any of the following:. A simple instruction consists of just the opcode. Other instructions may include one or more operands. Instruction can be one-byte instruction, which contains only opcode, or two-byte instructions, where the second byte is the operand or three byte instructions, where the operand makes up the second and third byte. Based on the operation they perform, all the instructions in the Microcontroller Instruction Set are divided into five groups.

The Data Transfer Instructions are associated with transfer of data between registers or external program memory or external data memory. The Mnemonics associated with Data Transfer are given below. The following table lists out all the possible data transfer instructions along with other details like addressing mode, size occupied and number machine cycles it takes.

Using Arithmetic Instructions, you can perform addition, subtraction, multiplication and division. The arithmetic instructions also include increment by one, decrement by one and a special instruction called Decimal Adjust Accumulator. The arithmetic instructions have no knowledge about the data format i.

Also, the operations performed by the arithmetic instructions affect flags like carry, overflow, zero, etc. All the possible Mnemonics associated with Arithmetic Instructions are mentioned in the following table. Logical Instruction are performed on Bytes of data on a bit-by-bit basis. As the name suggests, Boolean or Bit Manipulation Instructions deal with bit variables. These instructions can perform set, clear, and, or, complement etc. All the possible mnemonics of the Boolean Instructions are specified in the following table.