Question

principle of computer architecture

Section A Bahagian A Answer ALL questions from this section awab SEMUA soalan dari bahagian ini] Question 1 Soalan I (CI, CO1, POI) (a) Describe FOUR (4) basic functions of a computer system. ITerangkan EMPAT (4) fungsi asas sebuah sisiem komputer.) (4 Marks/Markah) (b) Describe the relationship between: [Terangkan hubungan di antara:] ) The width of address bus and the memory capacity. lebar bas alamat dan kapasiti memori. n The width of data bus and the data transfer. (ii) [lebar bas data dan pemindahan data] (2 Marks/Markah) (C2, CO1, PO1) (c) Briefly explain how short-I/O-wait-interrupt dprogram. [Terangkan pelaksanaan program pengguna] improve the execution of user can secara ringkas bagaimana sampukan-pendek-tunggu-/O boleh menambahbaik (2 Marks/Markah) (C4, CO1, PO1) (d) A very high performance computer system is to be built by considering the following requirements: Sebuah sistem komputer yang berprestasi tinggi akan dibina dengan mengambil kira keperluan- keperluan berikut:] (i) Explain FOUR (4) characteri stics of a memory system that need to be considered for the system. Assume that the design is for a multi-level memory system. (Terangkan EMPAT (4) ciri-ciri sistem memori yang perlu diambil kira untuk sistem tersebut. Andaikan bahawa rekaan tersebut ialah untuk sebuah sistem memori berbilang-tingkat. Tus SoluA (6 Marks/Markah) GSequential access is one of the methods to access units of data in a memory. List and justify TWO (2) methods of memory accessing that will be practical for the system. [Akses berjujukan adalah salah satu memori. Senaraikan dan justifikasi DUA (2) cara mengakses memori yang praktikal untuk sistem tersebut.] daripada cara untuk mengakses data di dalam sebuah (4 Marks/Markah) (iii) Suggest ONE (1) cache replacement algorithm and ONE (1) write policy that will suit the design. Explain your answer. [Cadangkan SATU (I) algoritma penggantian 'cache' dan SATU (I) polisi penulisan yang dapat disesuaikan dengan rekaan tersebut. Terangkan jawapan anda.] (3 Marks/Markah) (C3, CO1, PO1) Clele) Illustrate basic instruction cycle [llustrasikan kitaran arahan asas.] (4 Marks/Markah)

Answer 1

(a.) The four basic functions of a computer system is as follows:

• Input: the transfer of information into the system (e.g., through a keyboard).
•    Output: the presentation of information to the user (e.g., on a screen).
•    Processing: the retrieval or manipulation of information into a new form (e.g., results from a search engine).
•    Storage: the storing or preservation of information for later use (e.g., files stored on a hard drive).

(b.)

   (i.) Address bus will determine the size of memory.

For eg Consider 8086 processor where it has 16 bit registers and 20 bit address bus.Now the total address space that 8086 microprocessor can access upto 2^20 (2^n is the general formula were n is the size of the address bus) .

(c.) Short-I/O-Wait interrupt is generated by an I/O controller, to signal normal completion of an operation or to signal a variety of error conditions.These interrupts are provided to improve processor utilization. Most of the I/O devices are slower than the processor processor must pause to wait for device .Thus, creating interrupts prevents the wasteful use of the processor and thereby improves the execution of the user program by increasing the processor speed.

(d.)Four characteristics of a memory system is as follows:

(i.) 1) Location
   2) Capacity

   3)  Unit of Transfer

   4) Access Method

(ii.)

Direct access

• Individual blocks or record have an address based on physical location.
• Access is by direct access to general vicinity of desired information, then some search.
• Access time is still variable, but not as much as sequential access.

Random access

• Each addressable location has a unique, physical location.
• Access is by direct access to desired location,
• Access time is constant and independent of prior accesses.

(iii.)

Least Recently Used (LRU): This cache algorithm keeps recently used items near the top of cache. Whenever a new item is accessed, the LRU places it at the top of the cache. When the cache limit has been reached, items that have been accessed less recently will be removed starting from the bottom of the cache. This can be an expensive algorithm to use, as it needs to keep "age bits" that show exactly when the item was accessed. In addition, when a LRU cache algorithm deletes an item, the "age bit" changes on all the other items.

(e.)

A program residing in the memory unit of a computer consists of a sequence of instructions. These instructions are executed by the processor by going through a cycle for each instruction.

In a basic computer, each instruction cycle consists of the following phases:

1. Fetch instruction from memory.
2. Decode the instruction.
3. Read the effective address from memory.
4. Execute the instruction.