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ASSEMBLING AND DISASSEMBLING OF COMPUTER SYSTEM

ASSEMBLING AND DISASSEMBLING OF COMPUTER SYSTEM. WARNING!. ~ Unplug the system unit from the main power source. ~Do not tamper with the power box. ~Remove accessories that are metallic or can get caught in the system unit. DISASSEMBLING OF COMPUTER SYSTEM. Steps:

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ASSEMBLING AND DISASSEMBLING OF COMPUTER SYSTEM

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  1. ASSEMBLING AND DISASSEMBLING OF COMPUTER SYSTEM

  2. WARNING! ~Unplug the system unit from the main power source. ~Do not tamper with the power box. ~Remove accessories that are metallic or can get caught in the system unit.

  3. DISASSEMBLING OF COMPUTER SYSTEM Steps: Remove screws and cover. Unplug power cords. Unplug IDE and FDD ribbons from HDD, FDD and motherboard. Unlock and remove the cooling fan. Remove the RAM from the motherboard. Remove the hard disk drive carefully. Remove the floppy disk drive carefully. Remove the CD-Rom drive carefully. Unscrew and remove the PCI cover. Unscrew expansion cards(video card) and remove from the motherboard. Unscrew the motherboard diagonally from the last screw removed.

  4. RECAP! Remove system unit casing. Unplug all the power cords. Unplug IDE and FDD ribbons. Unlock and remove the cooling fan. Remove the RAM from the motherboard. Remove the various drives (HDD, FDD, CD Drive) carefully. Unscrew and remove the PCI cover. Unscrew and remove various expansion cards (video card, graphics card, NIC) from the motherboard. Unscrew the motherboard diagonally from the last screw removed.

  5. **Putting it back together** ~LAST OUT, FIRST IN~

  6. INTERPRETERS AND COMPILERS

  7. INTERPRETERS Translates and executes program statements one by one.

  8. COMPILERS Is a translator whose source language is a high-level language and whose object language is close to a machine language of an actual computer – either in assembly language or some variety of machine language.

  9. THE COMPILATION PROCESS LEXICAL ANALYSIS SYNTAX ANALYSIS SYMBOL TABLE MANAGEMENT SEMANTIC ANALYSIS ERROR HANDLING INTERMEDIATE CODE GENERATION CODE OPTIMIZATION CODE GENERATION

  10. LEXICAL ANALYSIS • -Is also referred to as scanning. • - In this phase, the stream of characters making up the source program is read from left to right and are grouped into tokens. • TOKEN - is a sequence of characters having a collective meaning. • LEXEME - the character sequence forming a token. • := called assignment operator • Example: identifier A := operand1 + operand2 * 70 • The identifier identifierA; • The assignment symbol := • The identifier operand1; • The operator +; • The identifier operand2; • The operator * and; • The number 70.

  11. SYNTAX ANALYSIS • -is also referred to as parsing. • In this phase, the tokens are grouped into grammatical phrases that are used by the compiler to generate output. Assignment statement := identifier expression + identifierA expression expression expression expression * identifier identifier number operand1 operand2 70

  12. SEMANTIC ANALYSIS - The process of type checking is an important task performed during this phase. := + id1 * id2 id3 int-to-real 70

  13. INTERMEDIATE CODE GENERATION -During this phase, the compiler generated an intermediate representation of the source program. temp1 := int-to-real (70) temp2 := id3 * temp1 temp3 := id2 + temp2 id1 := temp3

  14. CODE OPTIMIZATION -In this phase, some compilers attempts to improve the intermediate code generated by the previous phase(intermediate code generation). temp1 := id3 * 70.0 id1 := id2 + temp1

  15. CODE GENERATION • The last phase of the compilation process. • It is in this phase wherein the source program’s target code is generated. • F- signifies the fact that we are dealing with floating-point numbers • #-symbol that indicates a constant value • 1. MOVF id3, R2 • 2. MULF #70.0, R2 • 3. MOVF id2, R1 • 4. ADDF R2, R1 • 5. MOVF R1, id1

  16. SYMBOL-TABLE MANAGEMENT • The compiler performs an important function of recording the identifiers used in the source program and collect various attributes of each identifier. • SYMBOL TABLE REPRESENTATION • NAME OF IDENTIFIER TYPE LENGTH INITIAL VALUE • IdentifierA real 8 0 • Operand1 real 3 5 • Operand2 real 3 7 • ERROR DETECTION AND REPORTING

  17. OS SCHEDULING Types of Schedulers include: 1. First-Come, First-Served  (FCFS) 2. Shortest-Job-First  (SJF) 3. Priority Scheduling  (PS) 4. Round-Robin   (RR)

  18. Performance metrics include:CPU Utilization  - Percentage of time that the CPU is doing useful work (i.e. not idling). 100% is perfect.Waittime            - Average time a process spends in the run queue.Throughput     - Number of processes completed / time unit.ResponseTime    - Average time elapsed from when process is submitted until useful output is obtained.TurnaroundTime - Average time elapsed from when process is submitted to when it has completed.

  19. FCFS - simply executes processes to completion in the order they are submitted. EXAMPLE: PROCESS CPU REQUIREMENT TOA WAITING TIME P1 24 0 P1 = 0-0 = 0 P2 9 0 P2 = 24-0 = 24 P3 3 0 P3 = 33-0 = 33 36/36=1X100% 57/3-#of process = 100%-CPU utilization =19A.W.T. P1 P2 P3 0 24 33 36 Total turnaround time

  20. Shortest-Job-First (SJF)-is exactly like FCFS except that instead of choosing the job at the front of the queue, it will always choose the shortest job (i.e. the job that takes the least time) available. We will use a sorted list to order the processes from longest to shortest. When adding a new process/task, we need to figure out the where in the list to insert it.

  21. NON-PREEMPTIVE SCHEDULING • Is a strategy that even if a higher priority process is ready, the running process is allowed to continue until either it is locked or has completed its execution. • PREEMPTIVE SCHEDULING • - Is a strategy where the CPU is suspended when a higher priority process is in the ready queue.

  22. Priority (PRI)-is associated with each process. We can think of the SJF algorithm as a special case of PRI. Processes with equal priorities may be scheduled in accordance with FCFS.

  23. ROUND ROBIN (RR)-is a preemptive scheduler, which is designed especially for time-sharing systems. In other words, it does not wait for a process to finish or give up control. - In RR, each process is given a time slot to run. If the process does not finish, it will “get back in line” and receive another time slot until it has completed. We will implement RR using a FIFO queue where new jobs are inserted at the tail end.

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