Microprocessors (Electronics)

Microprocessor:

• CPU on a single chip.
• Fetches → decodes → executes instructions.

8085 Microprocessor:

• 8-bit data bus.
• 16-bit address bus → 64 KB memory.
• Clock: typically 3 MHz.
• Registers: A (accumulator), B, C, D, E, H, L; PC, SP, flag register.
• Pins: 40-pin DIP.

Flags (8085):

• Sign (S), Zero (Z), Auxiliary Carry (AC), Parity (P), Carry (C).

Addressing modes:

• Direct, Indirect, Register, Immediate, Implied.

Instruction types:

• Data transfer (MOV, MVI).
• Arithmetic (ADD, SUB, INR, DCR).
• Logical (AND, OR, XOR, CMP).
• Branch (JMP, JZ, JNZ, CALL, RET).
• I/O (IN, OUT).
• Stack (PUSH, POP).

8086 Microprocessor:

• 16-bit data bus.
• 20-bit address bus → 1 MB memory.
• Pipelined: prefetch + execute.
• Registers: AX, BX, CX, DX; SI, DI; SP, BP; CS, DS, SS, ES.
• Segmented memory model.

Modern Processors:

• 32-bit, 64-bit, multi-core.
• Pipelining, superscalar, out-of-order execution.
• ARM (mobile), x86 (PC/server).

Microcontrollers vs Microprocessors:

• Microcontroller: CPU + RAM + ROM + I/O on single chip. Used in embedded.
• Microprocessor: CPU only. Used in PCs.
• Common microcontrollers: 8051, AVR (Arduino), ARM Cortex-M, ESP32.

Memory hierarchy:

• Registers → Cache (L1, L2, L3) → RAM → SSD → HDD.

RRB JE focus: 8085 register set, instruction categories, microcontroller vs microprocessor.