adressing mode and types

(1) - BRIEFLY AND CLEARLY EXPLAIN WHAT IS ADDERESING MODE INTRODUCTION Addressing modes are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how machine language Instructions in that architecture identify the operand (or operands) of each instruction. An addressing mode specifies How to calculate the effective memory address of an operand by using information held in registers and/or constants Contained within a machine instruction or elsewhere. - Addressing modes: is said to be to be an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing mode that are defined in a given instruction set architecture defined how machine language instructions in that architecture identify the operands of each instruction. (2) List and briefly explain different types of addressing mode. i. Register Addressing Mode ii. Direct Addressing Mode iii. Indirect Addressing Mode iv. Immediate Addressing Mode v. Index Addressing Mode i- Register addressing mode: involves the use of registers to hold the data to be manipulated, it should noted that the source and destination registers must match in size. In other words coding “MOV DPTR, A” will give an error, since the source is an 8-bit register and destination is a 16-bit register. ii- Immediate addressing mode: although the DPTR register is 16-but it can also be accessed DPH is the high byte and DPL is the low byte. In this immediate addressing Mode, the data immediately follows the instruction. This means that the data to be used is already given in the instruction itself. iii- Direct addressing mode: when operands mode, direct access to main memory usually to the data segment is required. This way of addressing results in slower processing of data. To locate the exact location of data in memory, we need the segment start address which is typically found in the DS register and an offset value. iv- Indirect addressing mode: this addressing mode utilizes the computer’s ability of segment offset addressing generally the base registers EBX, EBP (or BX, BP) and the index registers coded within square brackets for memory references, are used for this purpose. v- Index addressing mode: the address of the operand is obtained by adding to the contents of the general register a constant value. The number of the index register and the constant value are included in the instruction code. Index mode is used to access an array whose elements are in successive memory locations. (3)- IDENTIFY AND BRIEFLY EXPLAIN ATLEAST FOUR (4) MODELS OF MICROPROCESSOR AND THEIR SIGNIFICANT. • INTEL MICROPROCESSORS • Pentium¨ (1993) • Pentium¨ II (1997) • Pentium II Xeon • Pentium¨ Pro (1995) • Pentium III Xeon (1999) • 4-BIT MICROPROCESSORS • MOTORALA 8-BIT MICROPROCESSORS • Celeron (1999)