ICT - Chapter 3 Memory and Processors PDF

Tr.ZML @ EDU4U INFORMATION AND COMMUNICATION TECHNOLOGY (ICT) 1  Tr.ZML @ EDU4U CHAPTER 3: MEMORY AND PROCESSORS 2  Tr.ZML @ EDU4U MEMORY 3 Memory...

Tr.ZML @ EDU4U INFORMATION AND COMMUNICATION TECHNOLOGY (ICT) 1  Tr.ZML @ EDU4U CHAPTER 3: MEMORY AND PROCESSORS 2  Tr.ZML @ EDU4U MEMORY 3 Memory Tr.ZML @ EDU4U ❑ Memory can be accessed faster than secondary storage. ❑ Memory is often called main memory or primary storage. ❑ Memory is used to store program instructions so that the processor can fetch the instructions quickly in order to execute them. ❑ Three types of memory: ▪ Random Access Memory (RAM) ▪ Read Only Memory (ROM) ▪ Flash Memory 4 Random Access Memory (RAM) Tr.ZML @ EDU4U ❑ Software is loaded into RAM from the secondary storage. ❑ The processor then fetches software instructions from memory, decodes and executes them. ❑ RAM is used to store programs/applications which are currently being used. 5 Characteristics of RAM Tr.ZML @ EDU4U ❑ RAM is volatile, meaning that the contents are lost when not powered. ❑ RAM can be changed (written), so applications can write data to it temporarily. ❑ RAM is bigger in size, so it can be used to store larger applications. ❑ RAM can be upgraded/increased for better system performance and multitasking. ❑ RAM stores temporary data. Note: Bold words are its characteristics and the latter part is how this characteristic affect the use of RAM/ROM. 6 Impact of the size of RAM on the UserTr.ZML ***** @ EDU4U ❑ When RAM space is not enough, the OS creates virtual memory by using an area of secondary storage. ❑ Secondary storage is much slower than RAM, so the user will notice a big decrease in system performance when the processor has to access instructions from virtual memory. Increasing the amount of RAM has benefit/good impact on the user: ✓ More applications can run at the same time (multitasking) because more instructions can be stored in the RAM, reducing the need to use slower virtual memory. ✓ Applications can run faster (no lag) because there is no need to rely on slower virtual memory stored in secondary storage. 7 Impact of the size of RAM on the UserTr.ZML ***** @ EDU4U ❑ When programs or files are closed, they are removed from RAM. As space in RAM becomes available, active programs are moved into RAM from virtual memory. ❑ A user can add more RAM to a system, but only up to the maximum supported by the computer and the OS. ❑ It can also be useful to increase the size of RAM when programs are updated because the updates often include more complex features that use more memory. RAM HDD/ SSD photo music virtual memory powerpoint word Music is closed!!! 8 Read Only Memory (ROM) Tr.ZML @ EDU4U ❑ ROM is used in computer systems that store only one program (single purpose computers) such as calculators, digital watches and washing machines. ❑ General purpose computers (PCs and laptops) use ROM to boot (start up) the system and load the OS from secondary storage. 9 Characteristics of ROM Tr.ZML @ EDU4U ❑ ROM is non-volatile, meaning that the contents are not lost even when power is turned off. ❑ ROM cannot be changed (not written), so applications cannot write data to it. ❑ ROM is smaller in size, so it is only used to store boot/start-up instructions. ❑ ROM cannot be upgraded/increased, because it is used to store permanent firmware/ BIOS and boot/start-up instructions. ❑ ROM stores permanent data. 10  Tr.ZML @ EDU4U Different Types of ROM (optional topic) 1) ROM refers to memory that cannot be changed after manufacture. 2) PROM refers to Programmable Read Only Memory. It is initially blank and can only be written to once after manufacture. ❑ Computer systems cannot swap instructions in and out of ROM, but it is possible to update programs stored in some types of ROM. ▪ EPROM (Erasable Programmable ROM) ▪ EEPROM (Electrically Erasable Programmable ROM) 3) Contents in EPROM can be erased by ultraviolet (UV) light. 4) Contents in EEPROM can be erased by applying an electrical voltage to one of its pin. ❑ EEPROM later developed into flash memory. 11  Tr.ZML Characteristics Comparison of RAM and @ EDU4U ROM 12  Tr.ZML Characteristics Comparison of RAM and @ EDU4U ROM RAM ROM RAM is volatile, meaning that the contents ROM is non-volatile, meaning that the contents are lost when not powered. are retained when not powered. RAM can be changed (read and written), so ROM cannot be changed (not written), so applications can write data to it temporarily. applications cannot write data to it. RAM is bigger in size, so it can be used to ROM is smaller in size, so it is only used to store larger applications. store boot instructions. RAM can be upgraded/increased for better ROM cannot be upgraded/increased, because system performance and multitasking. it is used to store permanent firmware and boot instructions. Note: Bold words are its characteristics and the latter part is how this characteristic affect the use of RAM/ROM. 13 Flash Memory Tr.ZML @ EDU4U ❑ Flash memory is a type of EEPROM. It is also ‘non-volatile’. ❑ It has no moving parts, so it has a fast access time, low power consumption. ❑ Because of low power consumption, flash memory is used in SSDs that are used in portable devices such as laptops since these devices rely on internal batteries. ❑ It is less likely to lose data when they the device is shaken or knocked because of no moving parts. ❑ Flash memory is also used as removable storage in USB drives and SD cards. 14 Flash Memory (2 marks approach) Tr.ZML @ EDU4U ✓ It has low power consumption because it has no moving parts, so it can be used in battery-operated devices/ the device’s battery will last longer. ✓ It has faster access time than HDD because it has no moving parts, so it can be used to quickly load large applications. ✓ It is less likely to fail/lose data when shaken/dropped because it has no moving parts, so it is robust. ✓ It is thinner/lighter because it has no moving parts, so it is better for carrying/ portable devices. Ꭓ It is more expensive per MB, so users must tolerate lower storage capacity. Ꭓ It has limited write cycles, so it is not suitable for write-intensive applications, making it eventually wear out. 15 Processors Tr.ZML @ EDU4U ❑ Function of a processor is to execute/ carry out/ run programs/ instructions/ data. ❑ A processor is made up of one or more central processing units (CPUs). Each CPU is referred to as a core. ❑ A quad-core processor has four cores that are working during each processor cycle. (four times as much work as a single-core processor) 16 Processors Tr.ZML @ EDU4U ❑ Processor cycle is the process of fetching a program instruction from RAM, decoding it and then executing it. ❑ Clock cycle is the number of times per second the a processor can execute instructions. ❑ Processor speed is the number of instructions that a processor can execute each second and is measured in clock cycles per second/ Hz/ GHz. 17 Activity Tr.ZML @ EDU4U Processor speed → Amount of work→ Amount of work by multicore processor → 18 Question Tr.ZML @ EDU4U Which one of these describes the term ‘clock cycle’? ---------- (1) A. The number of times per second that a processor can carry out instructions. B. The number of instructions that a processor can carry out each second. C. The number of times that a processor can load instructions for processing. D. The number of times that each process repeats in a processor. A 19 Question Tr.ZML @ EDU4U State one reason for increasing the speed of a CPU. (1 mark) Programs run more quickly 20 Question Tr.ZML @ EDU4U Explain one disadvantage of increasing the speed of the camera’s processor. (2 marks) It will reduce the battery life because it will use more power. (OR) The hardware could be damaged because the processor will generate more heat. 21 Question Tr.ZML @ EDU4U State what is meant by ‘ROM’. ---------- (1) Read Only Memory 22 Question Tr.ZML @ EDU4U State what is meant by ‘RAM’. ---------- (1) Random Access Memory 23 Question Tr.ZML @ EDU4U Explain why increasing the amount of RAM in a system improves the user experience. ---------- (3) Increasing the amount of RAM means that more programs can be open at the same time without needing to use virtual memory from secondary storage, which has slower access times than RAM. 24 Question Tr.ZML @ EDU4U Describe what virtual memory is and why it is used. ---------- (2) Virtual memory is an area of secondary storage used to store data when the computer system does not have enough space in RAM. 25 Question Tr.ZML @ EDU4U List THREE characteristics of RAM that make it different to ROM. ---------(3) Any THREE from: ▪ Volatile ▪ Data can be read from and written to ▪ Upgradable/ can be increased 26 Question Tr.ZML @ EDU4U List THREE characteristics of ROM that make it different to RAM. ---------(3) Any THREE from: ▪ Non-volatile ▪ Stored data cannot be changed/ Data cannot be written to ROM ▪ Non-upgradable 27 Question Tr.ZML @ EDU4U Explain TWO reasons why the characteristics of flash memory make it suitable for use as secondary storage in smartphones. ---------- (4) Flash memory has no moving parts, so it has low power consumption well suited for battery-operated smartphones. Since there is no moving parts, if the smartphone is knocked or shaken, it is less susceptible to data loss. 28 Question Tr.ZML @ EDU4U Smith has bought a smartphone that has 4 GHz CPU. Describe the function of CPU. ------------------ (2) ❑ Function of CPU/processor is to execute/ carry out/ run programs/ instructions/ data. 29 Question Tr.ZML @ EDU4U The amount of RAM in a computer can be increased. Explain one benefit to the user of increasing the amount of RAM. ------------------ (3) More programs can be run at the same time and having more RAM does not require virtual memory which has slower data access time than RAM. 30 Question Tr.ZML @ EDU4U One characteristic of RAM is that it can be increased. Describe how TWO other characteristics of RAM and ROM affect their use. ------------------ (4) Any TWO from: ❑ RAM is volatile meaning the ❑ ROM is non-volatile meaning the contents contents are lost when not powered. are retained when not powered. ❑ RAM can be changed, so ❑ ROM cannot be changed, so applications applications can write data cannot write data temporarily to it. temporarily to it. ❑ ROM is smaller, so is only used to store ❑ RAM is bigger, so it can be used to boot/start-up instructions. store large applications. 31 Question Tr.ZML @ EDU4U David has bought a camera. State one reason why David’s camera uses ROM. ------------------ (1) to store startup/boot instructions required for the camera 32