Note for Microprocessor - MP by ravi kumar

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Chapter 1 Microprocessor, Microcontroller and Programming Basics Course objectives • • • • to develop an in-depth understanding of o the operation of microprocessors and microcontrollers o machine language programming o microprocessor interfacing techniques to be able to use Motorola 68HC11 microcontroller competently to be able to design and implement microprocessor-based systems in both hardware and software to be able to apply this knowledge to more advanced structures Common computer organization ALU (Arithmetic Logic Unit) is a circuitry, which is capable of doing various operations (for example ADD, SHIFT, AND, OR, etc) on certain on-chip registers. CPU (Central Processing Unit) is the combination of the control logic, associated registers and the arithmetic logic unit. Computer buses Address bus: carries the address of a unique memory or input/output (I/O) device 1

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Data bus: carries data stored in memory (or an I/O device) to the CPU or from the CPU to the memory (or I/O device) Control bus: is a collection of control signals that coordinate and synchronize the whole system Block diagram of a typical CPU CPU structure The main functions are –data transfer –arithmetic and logic operations –decision making (instructional flow control) The register array consists of at least one accumulator, program counter and stack pointer. The control unit controls all the operations in a CPU and basically it puts the CPU in one of the fetch and execution phases. Memory The memory in a computer system stores the data and instructions of the programs. 2

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Main memory types • ROM (read-only memory) o programmed permanently at the factory, cannot be altered • RAM (random-access memory) o read and write memory • EPROM (erasable programmable ROM) o nonvolatile, written electrically but erased optically • EEPROM (electrically ROM) o nonvolatile, both written and erased electrically Operation of the CPU 3

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• • • Fetch cycle (phase): o The CPU puts the address of the instruction to be executed on the address bus. The address information comes from the program counter (PC) maintained by the control unit. o The control bus holds the information for reading the memory location and the data bus holds the instruction from the memory which is stored into the instruction register (IR) o PC is updated to point to the next instruction. Execute cycle (phase): o Instruction in the IR is decoded o The required data transfer and the required logical and arithmetic operation are performed o The result is written back either to one of the registers or memory or I/O device Common operations performed in ALU are: o addition, subtraction, o logical AND, OR, XOR, NOT o increment, decrement, shift, clear, etc. Microcomputer o o o o o o o CPU on a single IC microprocessor (µP). The terms CPU, µP and MPU (microprocessor unit) are synonymous CPU is the combination of the ALU and control unit of any computer. When the CPU is a single IC; it is called a µP and is also referred to as the MPU. When the MPU is connected to memory and I/O, the arrangement becomes a MICROCOMPUTER. Many different MPUs are produced by many different IC vendors (e.g., Motorola, Intel, Texas Instruments, Zilog, National Semiconductors, etc.). Major differences are in o word size, o the number and types of instructions that can be performed, o the types of external control signals available, o the amount of memory that can be addressed. 4