IB Computer Science SL (Chapter 2)
MIC: Step 2
Decode instruction in control unit •The instruction that has been received by the CU is then decoded. Decoding an instruction allows the CPU to be aware of any additional data that are necessary for the execution of the instruction. Any required data that need to be loaded from the primary memory in order for the instruction to be executable are then fetched The addresses of these data are placed into the memory (address) bus and the data from these addresses are received by the CPU through the data bus.
AND Gate
The AND gate is a digital logic gate with 'n' inputs one outputs, which perform logical conjunction based on the combinations of its inputs. The output of this gate is true only when all the inputs are true. When one or more inputs of the AND gate's inputs are false, then only the output of the AND gate is false. The symbol and truth table of an AND gate with two inputs is shown below.
Why is the Unicode character-encoding scheme needed?
The ASCII character encoding scheme can represent 128 different characters. This is enough for the lowercase and capital letters of the 26 letter Latin alphabet, as well as the space, punctuation and control characters. In order to incorporate all these different characters as well as the space, punctuation, mathematical and control characters into a single character-encoding scheme, it is necessary to represent far more than the 128 different characters of ASCII. That is why the Unicode character-encoding scheme was designed and is necessary throughout computer systems.
Characters
The American Standard Code for Information Interchange (ASCII) is a character-encoding scheme originally based on the english alphabet. This means that ASCII is used to represent text in computer systems. In oder to do this, a number is assigned to each letter from 0 to 127. (eg K = 75). ASCII used 7 bits to represent each character which means that it can achieve 2^7 = 128 different representations, or characters. It holds the latin alphabet as well as all the digits of the decimal numbering system (0-9)
NAND Gate
The NAND gate is a digital logic gate with 'n' inputs and one output, that performs the operation of the AND gate followed by the operation of the NOT gate.NAND gate is designed by combining the AND and NOT gates. If the input of the NAND gate high, then the output of the gate will be low. The symbol and truth table of the NAND gate with two inputs is shown below.
NOR Gate
The NOR gate is a digital logic gate with 'n' inputs and one output, that performs the operation of the OR gate followed by the NOT gate. NOR gate is designed by combining the OR and NOT gate. When any one of the inputs of the NOR gate is true, then the output of the NOR gate will be false. The symbol and truth table of the NOR gate with truth table is shown below.
NOT Gate
The NOT gate is a digital logic gate with one input and one output that operates an inverter operation of the input.The output of the NOT gate is the reverse of the input. When the input of the NOT gate is true then the output will be false and vice versa. The symbol and truth table of a NOT gate with one input is shown below. By using this gate, we can implement NOR and NAND gates
OR Gate
The OR gate is a digital logic gate with 'n' inputs and one output , that performs a logical conjunction based on the combinations of its inputs. The output of the OR gate is true only when one or more inputs are true. If all the inputs of the gate are false, then only the output of the OR gate is false. The symbol and truth table of an OR gate with two inputs is shown below.
XOR Gate
The X (exclusive)-OR gate is a digital logic gate with two inputs and one output. The short form of this gate is XOR. It performs based on the operation of OR gate. . If any one of the inputs of this gate is high, then the output of the XOR gate will be high. The symbol and truth table of the XOR are shown below.
MIC: Step 1
Fetch instruction from primary memory to control unit •The CPU is responsible for knowing which instruction it needs to take from the primary memory in order to operate correctly. To do that it sends the appropriate address through the memory (address) bus to the primary memory. The instruction that resides in the specific address is then copied into the data bus and sent to the control unit (CU).
AND Boolean Operator
Four states that the switches and the light can have at any point in time: •When both switches are open (0) and light is off •When switch number 1 is open (0) and switch number 2 is closed (1) the light is off. •When switch number 1 is closed (1) and switch number 2 open ()) the light is off (0) •When both switches are closed (1) the light is on (1)
Machine Instruction Cycle (MIC)
Functions of the CPU to run a computer program 1) Fetch instruction from primary memory to control unit 2) Decode instruction in control unit 3) Execute instruction 4) Store result of execution and check for next instruction
Control Unit (CU)
Responsible for the operation of the CPU. It controls the retrieval of instructions from the primary memory as well as the sequence of their execution.
DRAM and SRAM
SRAM is faster but more expensive than DRAM, and as such DRAMis preferred for the main RAM of a computer system. However, a small amount of SRAM is placed between the main RAM and the processor and is called the *Cache*. As such Cache is a smaller and faster RAM (SRAM)) that temporarily stores instructions and data so that the processor does not need to access the slower main memory (DRAM)
Menu
A GUI element that displays a list of commands that can be chosen by the usr to perform various functions. An example of a typical menu that displays operations related to creating, opening, closing, and saving a file.
Dialogue Box
A GUI element that is used to communicate information to the user and allow him/her to respond by choosing an option from a list of specific choices. An example of dialogue box that notifies the user that the full that is about to be closed is unsaved and allows the user to select from a list of possible events.
Web Browsers
A web browser is a software application used to access, retrieve, and present content on the World Wide Web. This content may be web pages, images, videos or other files and may be identified by a URI (Uniform Resource Identifier), eg https:// en.wikipedia.org/. The web browser uses a URI to connect to the appropriate web servers and request the wanted information. The web servers send back the information with the web browser then displays to the user.
(Electronic Mail) is a software application that allows for the exchange of digital messages from a single author to one or more recipients. The author and the recipient(s) do not need to be online simultaneously to exchange the email. The author of the email sends the email to the email server of the recipient(s), and when the latter connects to the server, they will receive the message. •An email consists of three components; the envelope, the header, and the body. In order for an email to be transferred from the author to the recipient(S), the Simple Mail Transfer Protocol (SMTP) is used. This protocol communicates delivery parameters using the message envelope. The message header contains information about the sender and the recipient(s) addresses, as well as the subject field and the timestamp. Finally, the message body contains the actual message which the author wants to send to the recipient(s). Email can be web-based, although this requires the user to be connected to the internet to use it. •Outlook and Gmail
Secondary Memory
(auxiliary storage) is a relatively slow memory that may be written to (like RAM) but is also non-volatile (just like ROM); meaning that the contents of the memory are not wiped if power is lost but are persistent. That is why secondary memory is also known as persistent storage. Furthermore, secondary memory has a relatively high capacity, to hold data compared to the primary memory.
Binary to Decimal Calculation
1) Start the decimal result at 0 2) Remove the most significant binary digit (leftmost) and add it to the result 3) If all binary digits have been removed, stop 4) Otherwise, multiply the result by 2 5) Go back to Step 2 6)To find a negative decimal number from binary digits, we invert the digits (0-->1, 1-->0) and Then add 1 *Negative binary numbers start with 1, and positive binary numbers start with 0*
Binary Number System
A positional system that uses two digits (0 and 1) to represent any number. The binary number system (or base-2) has two as its base. It is the most widely use number system in computer system in CS. Since base-2 is a positional system, the positional of each digit within a number provides the multiplier with which that digit is multiplied. Note that the multiplier is always a power of two with a base of 2 and and an exponent that increase by one compared with the exponent of the position to its right. Thus, each position has a value two times that of the position to its right.
Spreadsheets
A software application that is used for the organization and analysis of data. The data in a spreadsheet application is represented as cells, organized in rows and columns. These may contain numbers, text or results or formulas that calculate and display vales automatically on the basis of the contents of other cells. Spreadsheet software applications allow not only for the fundamental operations of arithmetic and mathematical functions to be shown, but also provide common financial and statistical operations and can display graphical data as well. Spreadsheet software application are used not only in accounting or finance, but also in any context that requires arithmetic data to be entered, processed and presented. •Microsoft Excel, and Apple Numbers
Word Processors
A software application that is used for the production of any sort of document. It includes tools for the composition, editing, formatting and possibly printing of documents. Word processing, is the action of creating documents using a word processor. This is the most common of all the main software application that can be installed on a computer system. •iPages, Microsoft Word
Command Line Interface
A system of user-computer interaction that operated on the basis of user typed commands.
Graphic Processing Software
Allows a user to manipulate visual images on a computer. A user can edit an image with the use of tools in various ways, such as selecting and moving, cropping, scaling, erasing, etc.. •Photoshop
Graphical User Interface (GUI)
Allows the user to interact with a computer in a number of ways instead of typing in commands. A GUI includes components such as graphical icons and visual indicators, as well toolbars, menus, and dialogue boxes. These allow the interaction between the user and the software application to be performed more smoothly through direct manipulation of the graphical elements.
Memory Management
An OS is responsible for all the memory that is available in a computer system. This means that an OS manages how the memory is used by applications and ensures that one application does not interfere with memory that one application does not interfere with memory that is being used by some other application. If one application interferes with another application's memory, the latter may stop functioning or its data may be affected or overwritten.
Resource monitoring and multitasking
An application that is running on a computer system takes up resources. These resources include the amount of memory the application is occupying, or how much processor time it needs in order to function properly. An OS is responsible for the efficient allocation of resources so that an application can run as effectively as possible on a particular computer system. •Multiple applications may run on a computer system at any one time, appearing as though they are performing tasks simultaneously, most computer systems however have a single CPU that can perform a single action at any particular time. That means that applications must share the CPU time in order to accomplish their goal. This is known as multitasking.
Binary to Hexadecimal
An equally easy way to convert from binary to hexadecimal is to group binary digits into sets of four, starting with the least significant (rightmost) digits. Binary: 11100101 = 1110 0101
Decimal Numbering
An example of a number in the decimal system is 6275base10. All numbers should state the base in which they belong. However, since the decimal system is the most widely used number system if the base is omitted it is assumed that the number is in the base 10 system.
Disk Access and Data Management
An important function of an operating system is its ability to access data stored in memory and disks. Data are stored using rules which are structured in such a way so as to make better use of the space available to the system, as well as to provide reliability and fast access times. The OS is responsible for keeping track of these files, as well as which files are being used by which application so that an application does not overwrite another applications' files. The OS is also responsible for coordinating the transfer of data from the disk file into the primary memory and vice versa.
Networking
An operating system manages connections to and with networks of other computer systems so as to allow the sharing of resources (such as files and printers). Networking is essential to modern computer systems, most connect with either a local area network or the Internet. An operating system acts as an intermediary between applications and networks allowing applications to interact with networks in a straightforward manner.
Security
Apart from allowing applications to run successfully, the OS is also responsible for the overall security of a computer system. The most common but effective method of protection is to provide some form of identity to the user that will allow his/her authentication. Most often a username and a password must be provided. However, other methods can be used, such as magnetic cards or biometric data. Apart from authentication methods, an additional security measure is the used of log files that keep trace of the activity of any user in the computer system. Anything a user does (reads writes or deletes files, changes some settings, etc) is recorded so that unauthorized users and activities may be discovered.
CPU
Central Processing Unit (CPU) a hardware component of a computer system and can perform basic arithmetic , logical or input/output operations in order to process data from input devices into useful information. The CPY is the "brain" of a computer system and can process data very quickly but can only prices data by following instructions- it cannot think for itself. It retrieves and saves data and information from and to the storage, which is the primary memory of the computer system. Any data or information that is to be saved on or retired from some storage medium (ex hard disk, CD, DVD, floppy disk, USB Stick) first has to pass through the primary memory in order to be accessed by the CPU. Contains the: •Control Unit (CU) •Arithmetic Logic Unit (ALU) •Memory Address Register (MAR) •Memory Data Register (MDR)
Bit, Byte, and their Multiples
Computer Systems are binary systems. That means that all the data and instructions that are stored in a computer system are stored in sequences of binary digits that can take only two possible values 1 and 0. Thus a binary digit (bit) is the basic unit of information in computer systems ad can have only two values: either 1 or 0. Eight bits form a byte. *1 byte = 8 bits* •A bit is denoted by the small letter b, whereas a byte is denoted by the capital letter B, thus 1B = 8b. One byte can store a single character. In a 64 bit computer, each memory location holds 64 bits. A 64 bit Memory (Address) Bus transfers 64 bit at any one time (which are the contents of a memory location in a 64 bit computer system) •In a computer systems we describe everything in bits and bytes. As such, they are used to denote file sizes stored on memory or disks (ex. a MB file) or even connection speeds (ex. Mbps) However , since files can become file can become quite large and connection speeds quite fast, multiples of bits and bytes are used. •Remember that 12MB is 8 times the size of 12Mb
Application software
Computer software designed to perform a group of coordinated functions, tasks, or activities for the benefit of the user.
Binary Computer Systems
Computers systems are binary systems, meaning that there are only two possible values that they can represent 0 and 1. These two values can be represented by a single binary digit, a bit. In order for such systems to represent more complex data, sequences of binary digits are used. The length of these binary digit sequences determines the possible number of different representations that can be achieved.
Computer Systems
Consist of hardware and software components and follow the concept of the input, process, output, and storage model. Thus, a computer system takes in some data as input, processes it a manner that we have requested and outputs the result in some way.
Registers
Contained in the CU. A register is a small storage location that can hold data, usually a multiple of 8 bits. For example a 64 bit computer has 64 bit registers. The size of the register in bytes is known as a *word*. -64 but register holds 8 bytes and each word has a size of 8 bytes, and every memory location will hold 64 bits.
Hexadecimal to Binary
Converting from hexadecimal to binary is as easy as converting from binary to hexadecimal. Simply look up each hexadecimal digit to obtain the equivalent group of four binary digits.
Hexadecimal to Decimal
Converting hexadecimal to decimal can be performed in the conventional mathematical way, by showing each digit place as an increasing power of 16. Of course, hexadecimal letter values need to be converted to decimal values before performing the math.
Decimal to Hexadecimal
Divide the decimal number by the desired target radix (16). Append the remainder as the next most significant digit. Repeat until the decimal number has reached zero.
Processing Phase of Input, Process, Output, and Storage Model
During the processing phase, other data, may be needed apart from the inputted. This data will exist in the storage of the computer system and will be used during the processing phase. New information that may arise may also be saved in the storage. Data or instructions are then processed by the computer system.
Converting sentences to Booleans
Ex: If is is hot and sunny, then we will go for a walk--> A * B = C where A = sunny B = hot, and C = walk
MIC: Step 3
Execute Instruction •The CPU execute the instruction using the necessary data that have been loaded and calculates a result. depending on the result, additional data may be needed. These data are fetched from the primary memory for further calculations. As before, the addresses of these data are placed into the memory (address) bus and the data from these addresses are received by the CPU through the data bus.
ROM
Holds instructions and data in unique memory locations, every such location has an address as well as content. Unlike RAM, the ROM is used to store permanent instructions and data that cannot be changed and are used to boot and operate the computer. As such, nothing can be altered in the ROM.
MDR
Holds the data that is to be used by the ALU and then saved to the RAM. The MDR is closely related to the MAR, since whichever memory address location the MAR is holding, the corresponding data will be loaded onto the MDR fro processing by the ALU. After the processing has taken place, the ALU places the result onto the MDR and the data is copied to the memory address location in RAM specified by the MAR. The connection between the RAM and the MDR is accomplished by the Data Bus.
Cache
Holds the information from the RAM that is most actively used, and accessed most frequently. The computer system will run faster as the slower main memory will need to be accessed less frequently. When the processor needs to be read from the main memory, it first checks if a copy of the data exists in the cache. If so, the processor reads from the cache, instead of reading from the main memory. This action speeds up the process. If the data to be read does not exist in the cache, the data are first copied to the cache and then used. When the processor needs to writ to the main memory it does so though cache memory.
MAR
Holds the memory address of the data to be used by the ALU, so that the ALU can fetch the corresponding content from the memory and process it accordingly. The MAR may also hold the memory address of where data that has been processed will need to be stores. In order for the MAR to communicate wit the primary memory, a connection is necessary. This connection is accomplished by the Memory (Address) Bus.
Operating System (OS)
Is a set of software that controls the computer's hardware resources and provides services for computer programs. It is a very important part of a computer system since it acts as an intermediary between software applications and the computer hardware.
Ex 2.1 Graphic Softwares
If secondary memory did not exist, we would not be able to run the graphics software without closing many programs in order to release some primary memory. However, the secondary memory allows us to run many programs concurrently and seamlessly. Since there is not enough space in the primary memory to load the graphics program, and other programs are computed into the secondary memory, this making space for the graphics program to be loaded into the primary memory. Whenever the program is moved into the secondary memory from the primary memory, some other program in the secondary program is copied into the primary memory. This process is called *Virtual memory*
Integers
Imagine that we use 8 bits to represent an integer number. That means that there can be 2^8 = 256 different representations, which means that 256 integer numbers can be represented. This would allow us to represent all the unsigned positive integers from 0-25, thus 256 different integer numbers. This method fails to cover how we can represent positive and negative numbers. For this calculation, we use the "sign and magnitude" representation. This method represents a number's sign by allocating the left-most bit as a sign bit to represent the sign. As mentioned before, the left-most bit is termed the MSB (0--> positive #, 1--> negative #). The rest of the bits indicate the magnitude of the number. As such, if we use 8 bits to represent an integer number and the MSB is the sign bit, only 7 bits remain for the magnitude, which means that 2^7 absolute values can be represented. This allows for numbers -127+ 127 to be represented.
Binary Fractions
In the binary system and in the decimal system, the binary point is used to separate the fractional from the whole part. For example the number 4.5 has 4 in its integer part and 1/2 in its fractional part. Suppose we want to concert this to binary. Assume that we will work using 8 bits.We are going to use 4 bits for the integer part and 4 bits for the fractional part. So this is a fixed point representation method.
Least Significant Bit (LSB)
Is the bit that helps determine whether the number is even or odd.
Toolbar
Is GUI element on which buttons, icons, menus, or other input or output elements are placed.
Random Access Memory (RAM)
Is a general-purpose storage area meaning that the data stored can be over-written. This allows data and instructions to be loaded for execution and use whenever the are necessary. However RAM is volatile, which means that whenever power is lost, the contents of its memory are wipes. (Unsaved changes)
Decimal Numbering System
Is a positional system that uses 10 digits (0-9) to represent any number, no matter how large or small. The decimal system (base 10) has 10 as its base and is the most widely used number system. The digits in the decimal system can be used with a decimal separator to represent a fractional part, as well as a plus/minus sign to indicate whetter the number represented is greater than or less than 0. Since base-10 is a positional system, the position of each digit within a number provides the multiplier by which that digit is multiplied. Note that the multiplier is always a power of 10, with a base of 10, and an exponent that increases by one compared with the exponent of the position to its right. Thus, each position has a value 10 times that of the position to its right.
Hexadecimal Number System
Is a positional system that uses 16 digits (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F). The hexadecimal number system (or base-16). Numbers in this system are known as hexadecimal numbers. Since base-16 is a positional system, the position of each digit within a number provides by the multiplier which that digit is multiplied. Note that the multiplier is always a power of 16, with a base of 16 and an exponent that increases by one compared with the exponent of the position to its right. Thus, each position has a value sixteen times that of the position to its right.
Read Only Memory (ROM)
Is used to store instructions and data and cannot be over-written. Thus means that the instructions that re embedded in ROM cannot be changed, even if power is lost, and as such is considered nonvolatile memory. ROM is used to store programs and instructions that do not need to be updated or changed. (Start-up instructions of the OS)
Instruction Cycle
It typically consists of four stages, fetch, decode, executer, and store
Colors
Many computer systems have a video display unit or monitor as an output device in order to communicate with the user. Monitors use pixels to display information and have a specific display resolution (eg 1440* 800). Each color value is represented as a hexadecimal value of two digits that may take up values from 00 to FF. Thus, in order to describe a color value in this way, a six-digit hexadecimal number is needed such as 70EF5A. The first two hexadecimal digits represent the Red color, the next two the Green color and the last two the Blue color. A little red (112), a lot of green (239) and a little of blue (90) combines to make a "lime" shade of green. The range of a two-digit hexadecimal number is from 00 to FF, which in decimal is from 00base 16 = 0*16 + 0*1 = 0base to FFbase15 =15*16 +15*1 = 255base10. The range of a six digit hexadecimal number is from 000000base16 to FFFFFFbase16. Since two hexadecimal numbers can represent 256c colors (from 0 to 255), six hexadecimal numbers (which are used to describe colors in computer monitors) can represent 256*256*256 = 16777216base10 district colors.
NAND Boolean Operator
Means *not and*
NOR Boolean Operator
Means *not or*
XOR Boolean Operator
One or the other but not both.
Arithmetic Logic Unit (ALU)
Performs all the basic arithmetic, logical or input/output operations. The CU is responsible for providing the ALU with the data that needs to be process as well as the instructions of how the data should be processed.
Peripheral Communication
Peripheral devices are all the hardware components of the computer system that reside outside the CPU. The OS is responsible to communicating directly with the hardware and providing an interface between hardware devices and applications. This allows for applications to use hardware devices in a trouble-free manner. •Printer, Keyboards, Monitors, Mice, Microphone, etc..
Database Management Systems (DBMS)
Software applications that manages (creates, queries, updates stores, modifies, and extracts information) databases and s designed to provide an interface between users and a database. A database can be defined as an organized collection of data. This data is organized into records and model some relevant aspects of reality. For examples, a database can store information about a school. All the data will be organized in records with each student's information organized in one record. The picture of the data base shown has three records (also called rows or tuples) and four fields (columns). Each record represents a set of related data.
Computer-Aided Design (CAD)
Software that assists engineers to create, modify, analyze and optimize a design. CAD is used in many fields an its purpose is to increase the productivity of the designer and the quality of the resulting design. Some examples of circumstances where CAD applications are used include automotive, shipbuilding, architectural design, and many more. CAD allows engineers to inspect a design from any angle or position. CAS can convey more than shape information. Materials, dimensions, tolerances can al be represented in such a way that when an engineer changes one value all the other dependent values automatically change accordingly. •Autodesk CAD, Adobe Inventor, Fusion 360
MIC: Step 4
Store result of execution and check for next instruction •After executing the instruction and computing the result the CPU then stores the result in the primary memory. To do so, it species the address where the result will reside in the primary memory, using the memory (address) bus and send the data through the data bus. The CPU then checks for the next instruction and repeats the steps described above by fetching, decoding, executing, and finally storing the result.
RAM
Stores the executing program instructions as well as any data that is needed. Instructions and data in the RAM are stored in unique memory locations and every such location has an address as well as content. The content is where the instructions and data resides whereas the memory location used by the CU to find, retrieve and access the data in order to send it to the ALU for processing.
Strings
Strings are sequences of characters. If the UTF- 8 (Unicode character encoding) encoding scheme is utilized, each character will be 8 bits, and under the assumption that 5 characters will be used in each word, then 5*8 = 40 bits will be needed for each word to be stored.
Example of a Binary Fraction
Suppose you want to find 12.3125.
NOT Boolean Operator
Switches the input and outputs it.
Binary digit
The basic unit of information in computer systems and can have only two values; either 1 or 0.
Most Significant Bit (MSB)
The bit position in a binary number having the greatest value.
Primary Memory
The only storage that is directly accessible y the CPU. At any point in time, the primary memory may hold both data and instructions that are currently running on the computer system. Data and instructions are stored as binary machine code in the primary memory.
OR Boolean Operator
There are four states that the switches and the light can have at any point in time: •When both switches are open (0) the light is off (0) •When switch number 1 is open (0) and switch number 2 closed (1) the light is on (1) •When switch number 1 is closed (1) and switch number 2 is open (0) the light tis one (1) •When both switches are closed (1) the light is on (1)
How are GUI's described?
WIMP- Windows, Icons, Menus, and Pointers
Importance of Secondary Storage
When a computer starts-up the RAM is empty. Instructions and data (such as the operating system) need to be copied into the RAM in order for the computer system to run. In most computer systems these are copied from the secondary memory. Secondary memory is thus what provides persistent storage to the computer systems. This is very important since if secondary memory did not exist, a computer system would be unable to store instructions and data persistently. Whenever shut down all the contents of the only existing primary memory would be lost. •Without secondary memory, only ROM would be able to store programs and instructions. This would mean that the computer could only perform fixed operations since ROM cannot be over-written.
Differences between Spreadsheet and a DBMS softwares
•A DBMS could be used for various data associations that cannot be created with spreadsheets. •A DBMS manages databases and serves a lot of users •A DBMS preserves data integrity easier •A spreadsheet can be used to produce charts and graphs using automated software tools •A spreadsheet can hold a limited amount of information •A spreadsheet usually serves the needs of a single person •Spreadsheet software can perform a lot of mathematical functions and perform data analysis.
Differences between cache memory and RAM
•Cache memory is nearer to the CPU than RAM •Cache memory is much faster than RAM •Cache memory is more expensive than RAM •Cache memory is separated in L1 and L2
*IB CS 2.1.12*
•Convert sentences to Boolean expressions •Develop and evaluate Boolean expressions using truth tables •Develop truth tables by combing the various boolean operators: AND, OR, NOT, NAND, NOR, and XOR
*IB CS 2.1.4*
•Define Machine Instruction cycle •Describe Machine Instruction cycle •Explain the use of data bus and address bus during the machine instruction cycle.
*IB CS 2.1.3*
•Define cache memory •Explain the functions of cache memory •Describe various types of ache memory
*IB CS 2.1.6*
•Define operating system •Explain the main functions of an OS
*IB CS 2.1.5*
•Define persistant storage •Explain the need for persistent storage •Define virtual memory •Explain the use of virtual memory
*IB CS 2.1.11*
•Define the Boolean operators: AND, OR, NOT, NAND, NOR, XOR. •Develop Truth Tables for the boolean operators: AND, OR, NOT, NAND, NOR, XOR.
*IB CS 2.1.7*
•Define the term application software •Define the terms word processors, spreadsheets, database management systems, email, web browsers, computer-aided design (CAD) and graphic processing software, and describe the use of these applications
*IB CS 2.1.1*
•Define the terms CPU, CU, MAR, MDR, Address bus and Data bus •Develop a diagram of the CPU showing connections between the elements mentioned above
*IB CS 2.1.9*
•Define the terms bit, byte, binary, deanery/decimal, and hexadecimal •Perform various calculations between different numbering systems.
*IB CS 2.1.8*
•Define the terms toolbars, menus, dialogue boxes, graphical user interface (GUI) and command line interface (CLI). •Identity features that are provided by the application software and features that are provided by the operating system.
Decimal to Binary
•Divide the decimal number by the desired target radix (2). •Append the remainder as the next most significant digit. •Repeat until the decimal number has reached zero.
Two types of RAM
•Dynamic RAM (DRAM) •Static RAM (SRAM)
*IB CS 2.1.2*
•Explain the use of primary memory •Define the terms RAM and ROM •Explain the differences between RAM and ROM
Examples of secondary memory
•Hard drive •CD-RW, DVD-RW •USB Flash drive •Secure Digital (SD) or Compact Flash (CF) card •Zip disk •Floppy disk •Magnetic tape
Basic CU registers
•Memory Address Register (MAR) •Memory Data Register (MDR)
Differences between primary and secondary memory
•Most computers are equipped with a smaller amount of primary memory and a larger amount of secondary memory •Primary memory is volatile, which means it does not retain data when the power is turned off •Primary memory is more expensive compared to secondary memory •Primary memory is much faster than secondary memory •Primary memory is directly accessed by the CPU •Secondary memory is not directly accessible by the CPU •Secondary memory is non-volatile, which mean it retains data when the power is turned off.
*IB CS 2.1.10*
•Outline the way in which strings, integers, characters and colors are represented in the computer •Outline the space required to store strings, integers, characters and colors in a computer •Describe the relation between the hexadecimal color code and the number of colors available
Services of an Operating System
•Peripheral communication •Memory management •Rescue monitoring and multitasking •Networking •Disk access and data management •Security
Differences between ROM and RAM
•ROM cannot be written to, but RAM can be written to •ROM holds the (BIOS) Basic Input/ Output system, but RAM holds the programs running ad the data used •ROM is much smaller than RAM •ROM is non-volatile (permanent), but RAM is volatile
L1/L2
•The L1 cache is placed on the microprocessor itself whereas L2 cache is placed between the primary memory and the microprocessor.
Common GUI elements
•Toolbar •Menu •Dialogue box
*IB CS 2.1.14*
•Use AND, OR, NOT, NAND, NOR, and XOR gates to develop a logic or Venn diagram •Convert a boolean expression to logic or Venn diagram
*IB CS 2.1.13*
•Use simplification rules to simplify a Boolean expression
Primary Memory
•Used as storage •Two types of memory: -Random Access Memory(RAM) -Read Only Memory (ROM)