BIOS and CMOS

Unit 3 and Unit 4 Review Materials

BIOS and CMOS

a. Explain the function of the BIOS ROM in the boot process.

The BIOS ROM is permanent storage device that contains startup instructions the computer.

b. Define flashing, with respect to BIOS ROM.

Flashing is a process of rewriting an EEPRO. This process allows the BIOS to be updated without changing ROM chips.

c. Explain the function of the CMOS in the boot process.

The CMOS contains the configurable system information that the BIOS reads during startup.

d. What is the advantage of having an unchangeable ROM and a changeable CMOS during the boot process?

By having an unchangeable BIOS, a default startup configuration is always possible. Since, however, startup configuration may differ from machine to machine, the changeable CMOS allows users to specify exactly how the boot will occur on their machines, possibly changing the startup from the default.

e. Consider that the CMOS has lost power.

i. What happens to the data that was stored in the CMOS?

The CMOS is a volatile and will lose all data contained in it if it loses power.

ii. How does the CMOS losing power affect the boot process?

When CMOS power fails it no longer contains configuration data, and therefore when machine is booted, it will use the default settings contained in the BIOS.

f. List two ways to change the information in the CMOS.

Windows Plug-N-Play, as an example.

BIOS setup and configuration utility, as an example.

4. Boot Process

a. What are two functions of the boot process?

The boot process ensures that crucial components of the computer system such as the memory, screen display, etc, are functional. It also loads the operating system form the hard disk into memory to enable the computer to be operational.

b. Describe the steps involved in a POST (include the information BIOS displays at the end of POST).

In a POST, first the video cards is enabled, then the amount of DRAM installed is determined, a memory test maybe performed, depending on the BIOS parameter setting, then the BIOS identifies expansion cards adapters that are present and initializes any it finds. At the end of POST, the BIOS displays system configuration information such as the type of processor installed, cache memory information, disk drives found, address of serial or parallel ports, and a list of expansion cards detected.

c. Fill in the following chart by arranging the steps of the boot process below in order.

o Copy BIOS to RAM

o Execute BIOS program

o Identify peripheral devices

o Load device drivers

o POST

o Search for Master Boot Record and load the operating system

Steps in the Boot Process

Power On

Execute BIOS program

Copy BIOS to RAM

POST

Identify peripheral devices

Search for Master Boot Record and load the operating system

Load device drivers

Operating System Operational

d. Explain what the term search order means in relation to the chart in part c.

The search order is the in which the master boot record is searched for.

Typically this order is floppy, CD-ROM,network,hard-drive.

e. Explain what the term bootstrap loader means in relation to the chart in part c.

The bootstrap loader is loaded when POST ends. It loads and the operating system.

5.Databases

What important, basic function do all databases serve?

A database is a collection of related information that a data error and duplication.

Explain the use of records and fields within a database.

A field is the smallest piece of data that a database can hold. (It is not necessarily small in size, but it is atomic.)

A record is one instance of a table in a database and represents one real-world object, and is therefore a collection of related fields.

What is a primary key, and how is it used?

A primary key is a column in the database for which each field has a unique value.

Primary key ensure that there is no data duplication, and allow for unique identification of any data set within a database.

In relation to a database, what function does SQL serve?

SQL is a data manipulation language that allows users to enter and retrieve data from the database.

List three examples of databases that you can interact with on the Internet.

www.amazon.com

www.imdb.com

www.loc.gov

6. Interrupts

Define hardware interrupt.

A hardware interrupt is a time-dependent, system that signifies that an I/O component needs attention.

Given that the system is currently running a process, list the steps the system performs to process an interrupt and return to the original process.

The system stops processing the current task and copies it to RAM.

The system copies the interrupt request the from RAM to the registers, and begins processing the new instructions.

The system finishes the interrupt request, and copies the original process back to the registers.

The system executes the original process until finished or interrupted.

What causes an interrupt?

An interrupt occurs when an I/O device needs attention. An interrupt occurs every time the keyboard is pressed, the mouse is clicked, sends data, etc.

What is interrupt priority?

Interrupt have differing priorities to determine the order in which they should be handled.

Give an example of a device that has a high interrupt priority and of a device that has a low interrupt priority.

A low-priority device would be the keyboard.

A high-priority device would be a SCSI CD-RW drive

o How are priorities assigned to devices?

Priorities are assigned to devices based on speed; high-speed devices have a high priority, while low-speed devices have a low priority.

7. Layers

o List the layers of software in order from lowest to highest.

1. Layers out of order

2. User-Written Scripts or Macros

3. User Interface

4. Application

5. Run-Time Libraries

6. Application Programming Interface

7. Operating System

8. Kernel

9. Device Drivers

10. BIOS

Describe encapsulation with respect to the layers of software.

Encapsulation means that a layer is closed off from other layers, achieving only it owns ends without knowing much about the other layers.

Describe abstraction with respect to the layers of software.

Abstraction is the means of sharing data and communicating that is established between various layers of software.

What advantage do encapsulation and abstraction give to software developers?

Encapsulation and abstraction allow developers to provide limited means of accessing data to their layer, and that they only must support limited influx of data from other layers` abstraction. The layer can be comprised of code that other layers need not be involved in.

Include an example of the advantage described in part d.

8. Multitasking

Define process.

A process is an instance of a running program.

What is the function of the process scheduler?

The process scheduler sends out interrupts at regular intervals. These allow the system to evaluate the process that should be running, and perform if necessary, a context switch.

Correctly label the state (running, runnable, blocked) each letter (A, B, C) represents:

A:runnable

B:running

C:blocked

Describe the steps taken by the system to perform a context switch.

The current process is stopped

The current process is copied to RAM

The new process is copied from RAM

The new process begins execution

Describe the effects from a user standpoint of pre-emptive multitasking.

Preemptive multi-tasking gives the illusion that all of the processes are running simultaneously and that the system in fact performing many tasks at once.

9. Operators

List three Boolean operators.

AND,OR,NOT

List three relational operators.

>, <, =.

How do Boolean operators function? Use the operators you listed in part a to help you create examples, if necessary.

Boolean operators manipulate the trueness or falseness of a statement. For instance, an AND says that something is true, if both expressions that it is joining are true.

How do relational operators function? Use the operators you listed in part b to help you create examples, if necessary.

Relational operators determine how two things relate. A relational operator may be part of an expressions that is Boolean, but it is not a Boolean operator

How do Boolean operators improve information searches?

Boolean operators allow the user to refine search criteria by restricting the field of possible true responses, so that the user can return responses that are most like what is wanted.

Give an example of a query that uses at least two of the Boolean operators.

Bank AND first NOT river

10. Software Development Life Cycle

Describe the Define stage.

Define is the stage when the problem is explored, the boundaries developed, and the problem explained.

Describe the Plan stage.

Plan is the stage that develops a system for implementing the aspects revealed in the define stage.

Describe the Code stage.

This is the stage where actual code is written and the developer constructs runnable software.

Describe the Test stage.

Once software are complete, they are tested for bugs, errors, and usability.

How do these stages of software development interact with one another?

These stage are more than part of a cycle, they are completely interactive. Any stage can lead to any other stage.

What is pseudocode?

Pseudocode is a mixture of English and a programming language that is used to plot out software development.

What life-cycle stage would pseudocode be used in?

Pseudocode is used in the plan stage.

11. Software Licenses

Define shrink-wrap license.

Define shareware license.

Define public-domain license.

For each type of license listed in parts a, b, and c, give one example of a program distributed under that type of license.

12. Traps and Faults

What is a trap? How are traps triggered?

What is a fault? How are faults triggered?

How does the system handle traps and faults?

What is a page fault? How are page faults triggered?

List the steps the system takes to resolve a page fault.

14. Virtual Memory

a. What three advantages does the course mention, regarding virtual memory?

b. What is one disadvantage of virtual memory?

c. What data is contained in a swap file and where does the swap file reside?

d. How does virtual memory work using a page table?

e. Given pages 2, 3, and 5 are already in main memory (the memory is not yet full). What happens when a request for page 6 is made? What role does the kernel play in processing this request?

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