ICT: Chapter 3 - Memory and Processors

• Chapter 3 focuses on memory and processors in ICT

Memory

• Memory can be accessed faster than secondary storage
• It's often referred to as main memory or primary storage
• Used to store program instructions for quick access by the processor

Three Types of Memory

• Random Access Memory (RAM)
• Read Only Memory (ROM)
• Flash Memory

Random Access Memory (RAM)

• Software is loaded into RAM from secondary storage
• The processor fetches, decodes, and executes software instructions from memory
• RAM stores programs/applications that are currently being used

Characteristics of RAM

• Volatile: Contents are lost when power is off
• Changeable: Can be written to temporarily by applications
• Larger in size: Accommodates larger applications
• Upgradable: Increases system performance and multitasking capabilities
• Stores temporary data

Impact of RAM Size on the User

• When RAM is insufficient, the OS uses virtual memory on secondary storage
• Secondary storage is slower than RAM, resulting in decreased system performance

How RAM Impacts the User

• With more RAM:
• More applications can run simultaneously (multitasking)
• Applications run faster
• Programs/files are removed from RAM when closed to free up space
• More RAM is useful when programs are updated with complex features
• The computer can only handle an allocated maximum of RAM

Read Only Memory (ROM)

• ROM is used in systems storing only one program, such as calculators
• General purpose computers (PCs, laptops) use ROM to boot the system and load the OS from secondary storage

Characteristics of ROM

• Non-volatile: Contents are retained even when the power is off
• Unchangeable: Applications cannot write data to it
• Smaller in size: Only used to store boot/start-up instructions
• Non-upgradable: Stores permanent firmware/BIOS and boot instructions
• ROM stores permanent data

Different Types of ROM

• ROM: Memory that cannot be changed after it's manufactured
• PROM (Programmable Read Only Memory): Initially blank, written to once after manufacture
• Updating programs is possible in some ROM types
  • EPROM (Erasable Programmable ROM) can be erased by ultraviolet (UV) light
  • EEPROM (Electrically Erasable Programmable ROM) erases contents by electrical voltage
  • EEPROM evolved into flash memory

Characteristics Comparison of RAM and ROM

• RAM:
• Data is stored only when power is on thus 'volatile'
• Swap instructions in and out
• Accessible in any order
• Intended for temporary data storage
• Can be upgraded or increased
• ROM:
• Data is stored even when the power is off thus 'non-volatile'
• Instructions not swapped in and out
• Accessible in any order
• Intended for permanent data storage
• Cannot be upgraded or increased

Flash Memory

• A type of EEPROM
• Non-volatile
• Has no mechanical parts allowing:
• Fast access
• Low power consumption
• It is used in SSDs for laptops due to low power needs and reliance on batteries
• Less likely to lose data when shaken or knocked due to lack of moving parts
• Used in USB drives and SD cards

Flash Memory Advantages

• Low power consumption: Battery lasts longer on devices
• Faster access time: Quickly loads large applications
• Less likely to fail/lose data: Robust when shaken/dropped
• Thinner/lighter: More portable
• Disadvantages:
• More expensive per MB
• Not suitable for write-intensive applications

Processors

• Functions to execute/carry out/run programs/instructions/data
• A processor is made up of one or more CPUs
• A core is part of a processors make-up
• A quad-core processor has four cores working at each processor cycle

Processor Terms

• Processor cycle: Process of fetching program instruction from RAM, decoding, and executing
• Clock cycle measures amount of times per second a processor can action instructions
• Processor speed: The number of instructions to execute each second, measured in clock cycles per second (Hz/GHz)

Chapter 3 explains computer memory and processors in ICT. Primary memory allows quicker access than secondary storage. It covers RAM, ROM and Flash memory. This section describes the characteristics of RAM, its volatility, changeability and impact of RAM size.