section 1 - components of a computer system Flashcards
Embedded systems
- embedded Systems are computers built into other devices, like dishwashers, microwaves and washing machines - It’s used when the bigger machine has a restricted set of instructions that are unlikely to change.
CPU
Processes all the data and instructions required to make the system work. Central Processing unit
CPU - Clock speed
This is the number of instructions a single processor core can carry out per second (Hz). For most desktop computers, this will be somewhere around 3.5 GHz (3.5 billion instructions per second). .The higher the clock speed, the greater the number of instructions that can be carried out per second.
Some CPUs can be overclocked to make them run at a higher clock speed than the factory-set rate. But it’s risky if not done properly - it can make CPUs overheat, causing crashes or permanent damage to the system. High performance cooling systems (e.g. water cooling) are usually needed.
CPU - number of cores
Each core in a CPU can process data independently of the rest. * The more cores a CPU has, the more instructions it can carry out at once, so the faster it can process a batch of data.
* Most PCs and smartphones have 4 or more cores these days.
CPU - cache size
- The cache is data storage inside the CPU that’s much faster than RAM. * A larger CPU cache gives the CPU faster access to more data it needs to process.
More RAM can mean a Faster or Smoother System
1) If a computer has too little RAM it may run slowly due to the use of virtual memory
2) The more RAM, the more applications, or more memory-intensive applications it can smoothly run, making it faster overall.
3) It’s easy to upgrade RAM on a PC or laptop - it’s just a matter of replacing the RAM sticks with higher capacity (or higher speed) ones.
4) If the computer already has plenty of RAM to run everything the user wants, increasing RAM may make no difference to performance.
GPUS help CPUs process Images.
1) GPUs (graphics processing units) are specialised circuits for handling graphics and image processing. They relieve the processing load on the CPU, freeing it to do other things.
2) Computers have basic GPUs integrated onto the motherboard or the CPU. For better graphics performance, a dedicated GPU (graphics card) is often used.
3) Using high-end graphics cards can greatly improve performance in graphics-intensive applications, e.g., PC gaming and design software.
Volatile memory
Volatile memory is temporary memory. It requires power to retain its data.
Non-volatile
Non-volatile is permanent memory it keeps its contents even when it has no power.
RAM
RAM is High Speed, read, write, Volatile memory.
1) RAM (or Random Access Memory) is volatile memory with fast access speeds
2) contains all data, files and programs, and the OS while they’re being used.
3) When a computer boots up, the operating system is copied from secondary storage to RAM.
virtual memory
Virtual memory is the use of secondary storage as extra RAM when the ram is full.
much slower than RAM
When RAM is full, the computer moves data that hasn’t been used recently to a location on secondary storage which is known as virtual memory.
If the CPU needs to read data stored in virtual memory, it must move the data back to RAM. This is slow as data transfer rates are much slower on secondary storage than RAM.
ROM
1) ROM (Read Only Memory’) is non-volatile memory.
2) ROM comes on a small, factory-made chip built into the motherboard.
3) It contains all the instructions a computer needs to properly operate. These instructions include the BIOS (Basic Input Output System), POST (Power on Systems Test) and the bootstrap.
4) As soon as the computer is powered on, the CPU reads the instructions from ROM. This tells the CPU to perform self-checks and set up the computer, e.g., test the memory is working OK, see what hardware is present and copy the operating system from secondary storage into RAM.
3 types of storage
- Primary storage
- Secondary storage
- Tertiary storage
Primary storage
Primary storage refers to the memory areas that the CPU can access very quickly, like CPU registers, cache, ROM and RAM. Primary storage has the fastest read/write speeds and is mostly volatile
Secondary storage
Secondary storage is non-volatile-it’s where all data (operating systems, applications, and user files) are stored when not in use. It includes magnetic hard disk drives, solid state drives, CDs, and SD cards. Read/write speeds are much slower compared to primary storage.
Tertiary storage
Tertiary storage is used for long term data storage (it’s mainly uses for archives and back-ups of massive amounts of data)
Solid State Drives
1) Solid State Drives (SSDs) are storage devices with no moving parts. SSDs are used for the same purpose as HDDs for internal/external storage.
2) Most SSDs use a type of flash memory (a common type of non-volatile memory).
3) SSDs have significantly faster read/write times than HDDs.
Hard Disk Drives
A hard disk drive is made up of a stack of magnetised metal disks that spin thousands of times a second.
Data is stored magnetically in small areas on the disk’s circular tracks.
A moving arm can access these areas and read or write data.
Despite their moving parts, HDDs are generally very long lasting and reliable, although they could be damaged by large impacts like being dropped.
Hybrid drives
Hybrid drives exist which use solid state storage for the OS and programs, and a hard disk for data.
portable high capacity storage
Portable HDDs & SSDs are popular for backing up and transporting large amounts of data.
Other types of flash storage
USB pen drives and memory cards (e.g., SD cards) are also flash-based, solid-state storage.
They’re much slower than SSDs and have a much shorter read/write life. They’re used to expand the storage capacity of small devices like cameras, smartphones, and tablets (which are too small for SSDs or HDDs). Their capacity is very high relative to their tiny size.
Advantages of HDDs
HDDs are cheaper.
Both are high capacity, but HDDs are higher.
HDDs have a longer read/write life than SSDs - SSDs can only be written a certain number of times before they begin to deteriorate.
Advantages of SSDs
SSDs are faster.
SSDs don’t need defragmenting.
SSDs are more shock-proof than HDDs.
HDDs make some noise, SSDs are silent.
optical discs
Optical discs are things like CDs, DVDs, and Blu-ray discs.
CDs can hold around 700 MB of data, DVDs can hold around 4.7 GB and Blu-rays can hold around 25 GB.
Optical discs come in three forms:
-read-only (e.g., CD-ROM/DVD-ROM/BD-ROM)
-write-once (e.g., CD-R/DVD-R/BD-R)
-rewritable (e.g., CD-RW/DVD-RW/ BD-RW)
Data is stored as microscopic indentations (pits) on the shiny surface (lands) of the disc.
