Untitled Quiz

Introduction

• Microprocessor is a program-controlled semiconductor device, functioning as a computer's brain.
• It fetches, decodes, and executes instructions.
• It serves as the CPU in computers.
• An example of a microprocessor is the 8085.
• Intel created the 8085 in 1976.

Computer System Block Diagram

• A computer system comprises input devices, the CPU, memory, and output devices.
• Data flows from input devices to the CPU, then to memory, and finally to output devices.
• This diagram illustrates the fundamental structure of a computer system.

Types of Computers

• Computers are broadly categorized as analog and digital.
• Digital computers further classify into microcomputers, multiprocessor computers (or supercomputers).
• A microcomputer has one microprocessor.
• Examples include desktop, laptops, mobile phones, and notebooks.

Microcomputer

• A digital computer containing one microprocessor.
• Examples: Desktop, laptop, mobile phone, notebook.
• Microcomputers utilize a microprocessor as their central processing unit.
• They include components such as a keyboard, microprocessor (or CPU), memory, and a display unit.

Multiprocessor Computer

• A digital computer with more than one microprocessor.
• Examples: Desktop, laptops, mobile phones, notebooks.

Word Length of Microprocessor

• Word length is expressed in n-bits. Common values for n include 8, 16, 32, and 64.
• An 8-bit processor operates on 8-bit data at a time.
• Processing larger data (e.g., 16-bit) requires multiple operations by an 8-bit processor.
• Similarly, 16-bit and larger processors handle the data correspondingly.
• Larger word lengths enable faster and more complex operations.

Evolution of Microprocessor

• A table detailing different microprocessor models, their introduction years, word lengths, memory addressing capacity, pins, and clock frequencies is presented.
• Microprocessor models evolved from 4-bit to 64-bit types.
• Memory addressing capacity and clock frequencies increased over time.

Unit-I: Microprocessor 8085

• The Intel 8085 is an 8-bit NMOS microprocessor.
• It is a 40-pin IC (integrated circuit) housed on a single LSI chip..
• The 8085 operates using a +5 Vdc supply.
• Clock speed ranges from 3 MHz to 6 MHz.
• The clock cycle duration for the Intel 8085 AH-2 is 200 ns.
• The 8085 has 80 basic instructions and 246 opcodes.
• It functionally comprises an Arithmetic and Logic Unit (ALU), a Timing and Control Unit, and registers.

8085 Microprocessor Architecture

• A diagram illustrating the 8085 architecture is provided.
• Key components include the accumulator, temporary register, status flags, instruction register, arithmetic logic unit (ALU), timing and control unit, and other registers.

ALU (Arithmetic & Logic Unit)

• The ALU performs arithmetic and logical operations such as addition, subtraction, logical AND, logical OR, logical exclusive OR, complement, increment, decrement, shifts, rotations, and clear.

Timing and Control Unit

• The timing and control unit governs the entire operation of the microprocessor and connected peripherals.
• It controls the flow of data between the CPU and peripherals, including memory, and generates essential timing and control signals for instruction execution.

Registers

• Registers are temporary memory components of the microprocessor.
• Registers store data until transferred to memory or I/O (input/output) devices.
• Microprocessors with larger numbers of registers facilitate faster data transfer.

Specific 8085 Registers

• The 8085 microprocessor contains an 8-bit accumulator (register A), six 8-bit general-purpose registers (B, C, D, E, H, L), a 16-bit stack pointer, a 16-bit program counter, an instruction register, and a temporary register.

General-Purpose Registers

• The 8085 includes six 8-bit general-purpose registers (B, C, D, E, H, L).
• These registers can be paired (e.g., B-C, D-E, H-L) for 16-bit data storage or memory addressing.

Program Counter (PC)

• The 16-bit PC maintains the memory address of the next instruction to be executed.

Stack Pointer (SP)

• A 16-bit special register that controls stack addressing.
• It holds the address of the top element in the stack.
• The stack is a sequential memory for storing and retrieving data.

Instruction Register

• The instruction register holds the opcode of the current instruction being decoded and executed.

Temporary Register

• An 8-bit register associated with the ALU, used for storing data during arithmetic and logical operations.

Flags

• The Intel 8085 microprocessor includes five flip-flops used as status flags, reflecting ALU operation status.
• These flags include: Carry Flag (CS), Parity Flag (P), Auxiliary Carry Flag (AC), Zero Flag (Z), and Sign Flag (S).

8085 Pin Diagram

• Details of pins in the 8085 architecture are presented visually via a pin diagram.
• Pin descriptions detail functions like address bus (A8-A15), data bus (AD0-AD7), address enable (ALE), input/output (I/O) signal (IO/M), control signals (READY, HOLD), and interrupt lines.

Addressing Modes

• Different techniques to specify data for instructions are outlined.
• Modes include direct, register, register indirect, immediate, and implicit addressing.

Instruction Word Size, Addressing

• Instructions are classified as 1-byte, 2-byte, or 3-byte instructions based on their length.
• 1-byte instructions use immediate data, while 2-byte instructions involve addressing or data, and 3-byte instructions typically use larger data or addresses.
• Examples for each are provided.

Addressing Modes

• Instructions utilize specific addressing modes to specify data (e.g., direct, register, register indirect, immediate, implicit).
• Examples of various addressing modes are included.

Branch Group

• Unconditional and conditional branch instructions change the normal sequence of program execution.
• Instruction jump to a specified label/address.

Conditional Instructions

• Conditional jump instructions execute based on conditions (e.g., zero, carry, parity).
• Example instructions are outlined

Programming Example

• Assembly language code examples of data transfer, arithmetic operation, and other operations are presented

Subroutine Call and Return

-Instructions for subroutine calls (e.g., CALL addr) and subroutine returns (RET).

I/O & Machine Control Group

• Instructions for input and output operations (IN, OUT).

Miscellaneous Instructions

• Instructions like HLT (Halt).

Restart

• Restart instructions, enabling fast jumps to predetermined locations in the program.