MICROPROCESSOR AND MICROCONTROLLER

Detailed explanation-1: -With only 4 bits for the instruction opcode, there’s a maximum of 16 different instructions, so the choice of which instructions to implement is challenging. It would be possible to have more than 16 instructions, but only by shrinking the address size or immediate operand size.

Detailed explanation-2: -ALL instructions are 16 bits in length. Shift immediates can be restricted to 2 bits.

Detailed explanation-3: -The opcode size (its bus width) determines the maximum number of distinct operations the ALU can perform; for example, a four-bit opcode can specify up to sixteen different ALU operations.

Detailed explanation-4: -If the data is 8-bit, then the instruction will be of 2 bytes, if the data is of 16-bit then the instruction will be of 3 bytes. Register Addressing Mode In register addressing mode, the data to be operated is available inside the register(s) and register(s) is (are) operands.

Detailed explanation-5: -Five bits would allow 32 instructions total and 6 bits allows up to 64 instructions. Because 48 falls between 32 and 64, a 6-bit field must be used to ensure a complete set of unique binary opcodes. The opcode bit field defines the number line of opcode values. We call this number line the opcode space.