1. Hardware Flashcards
What is Von Neumann?
- The VN architecture used the idea of storing programs instructions and data in main memory and moving them between memory and the processor.
- The processor can access the instructions and data in the main memory as required to execute the program. by using buses.
- This means the same address and data buses are used to transfer instructions and data.
What is Harvard Architecture?
Harvard architecture keeps instructions and data in separate memories which the processor accesses using separate data and address buses.
Harvard is used extensively in embedded systems.
How does multiple cores affect performance?
The more cores a computer has, the more instructions it can execute at the same time so the computer will perform more efficiently.
What is parallel processing?
Dividing a computation into subtasks that can be processed in parallel (one task per core at the same). This is known as parallel processing and it is only possible on multicore systems
Communication and synchronisation between the different subtask are typically some of the greatest obstacles to getting efficient parallel program performance
How does a larger cache affect system performance?
The larger the cache, the more instructions can be queued and carried out. Storing instructions in cache reduces the amount of time it takes to access that instruction and pass it to a CPU core.
How does clock speed affect performance?
The greater the clock speed, the faster the instructions. Making a processor perform more instructions per second than it is recommended to (overclocking), could cause the processor to overheat.
Describe The FDE Cycle
1.The program counter (PC) keeps the address of the next instruction to be executed. The contents of the PC are copied to the memory address register (MAR), which is connected to the address bus. The address of the next instruction to be executed is placed on the address bus.
2.Once the address of the instruction is on the address bus, the control unit instructs a memory read operation to allow the contents of the memory location to be transferred to the processor. The instruction that is stored at that address is transferred from the main memory to the processor (using data bus) , and is saved in the memory data register (MDR). The PC is incremented by 1.
3.The contents of the memory data register (MDR) are copied to the current instruction register (CIR).
4.The control unit decodes the instruction that is kept in the current instruction register (CIR) and the instruction is executed. Depending on the type of instruction, executing an instruction can involve the ALU and the general-purpose registers, the accumulator, or the main memory.
What is the purpose of secondary storage?
- Secondary storage provides permanent storage for data files and applications.
- Secondary storage is non-volatile (so data is not lost when power is removed).
- Secondary storage needs to be high capacity and low cost. It needs to be fast enough for loading and saving files, and it needs to provide reliable permanent storage so that files are not lost or easily corrupted.
What is a network?
A network is a group of devices connected together, wirelessly or using cables, so they can communicate with each other and share resources.
What is the importance of networking standards?
Network standard allows communication between different network devices so its impossible to create networks that communicate without them.
- Easier to develop – can be done one layer at a time
- Allows different companies to work together / international standardisation
- Leads to more competitive pricing
What’s HTTP(S)?
Hypertext Transfer Protocol is used to make a request for a webpage. HTTPS uses protocol (TSS/TLC) to encrypt the data making it more secure.
What is FTP?
File Transfer Protocol is used for the transfer of computer files from a server to a client on a computer network. It’s used for sharing files with other users, either for storage or collaboration.
What is SMTP and IMAP?
Simple Mail Transfer Protocol transfers the email from the client device to the linked mail server.
Internet Message Access Protocol is used to synchronise a client email account with an account on the mail server. The server returns new emails and deletes any emails that were deleted locally on the client application.
What is TCP and UDP?
TCP is more reliable and makes sure every data packet arrives by using an error checking feature.
UDP is faster but less reliable so if any packets arrive out of sequence or are missing, they are ignored.
TCP - video streaming services
UDP - video games
What is Handshaking?
Handshaking is the process that establishes communication between two networking devices.
What is the internet?
The internet is a global network of interconnected networks that communicate using a common set of standards and protocols.
What are the functional characteristics of a HDD?
- The drive is a mechanical device with many moving parts.
- Hard drives have a fast transfer rate and a fairly fast access time.
- Hard drives are a magnetic medium and store data on a hard drive platter.
- Hard drives consist of an actuator arm which attaches to a RW head which moves across the disc reading/writing data.
- The faster the platter spins, the faster the data can be read from the disk. A common speed for a hard drive can be 7200 RPM but it can vary.
-Fragmentation occurs when there is insufficient contiguous space to store the file. Each part of the file will be in a separate location which has to located, taking longer to access the file.
- Good capacity and cost
What is SSD?
- An SSD is an electronic device that uses flash memory, and has no moving parts.
- Greatest access speed
- The absence of moving parts means that mechanical failure is far less likely. The lack of moving parts also reduces the amount of energy consumed, which, in turn, reduces the amount of heat generated in a computer system.
- Limited lifespan. The number of times that an SSD can be written to is finite, and memory cell ‘leakage’ can be a problem if devices are not powered up
- more expensive (per GB) compared to HDD
-SSDs are particularly suitable for storing files that are read or changed frequently.
Name and describe the function of main components in the CPU
CU - Directs the flow of data
- Coordinates the other parts of the CPU
- Generates clock ticks
ALU - Carries out simple calculations and logical operations
Registers - small/fast access/ temporary storage used to store frequently used data and instructions .typically addressed by mechanisms other than main memory
buses - connects all the internal components of a computer such as CPU and memory to the motherboard.
What is DHCP
Assigns dynamic IP addresses to devices on a network. This is important as the protocol/p returns unused addresses to the pool of available IP address for reallocations
What is caching?
Used to store frequently used data from memory.
- Faster than Ram but volatile
- Similar to Ram but resides closer to the CPU
- used by processor to avoid having to slow down to the speed of RAM
- different level of cache which denote speed and characteristics
What is UDP
Universal Datagram Protocol is responsible for sending datagrams across a network with very few error recovery services.
Optical Drive
Optical drives work by using lasers to store data
Burning microscopic indentations, in a spiral pattern, into a disc such as CD
Indentations and their absence creates pits and lands
When the laser shines on the disc’s surface, lands reflect the light back, whereas pits scatter the laser beam. A sensor looks for the reflected light. Reflected light (lands) represents a binary ‘1’, and no reflection (pits) represents a binary ‘0’.
On bluray, pits and lands are closer together, meaning that the laser’s wavelength is shorter (blue)
DVD-ROM uses the same techniques to store data, but the data is stored on two layers.
- Portbale
- Can buy in large batches
- More durable
- longevity - fairly robust, susceptible to scratching if not well protected
What is a protocol?
A protocol is an agreed upon format which allows two devices to communicate
What is TCP/IP?
Allows any networked computers to communicate with each other. This is important as TCP/IP specifies how signals are routed and transported around a network.
What is Application Layer
The layer where user-interface applications operate, involving protocols that user applications interact with like HTTP,FTP etc.
Transport Layer
Responsible for end-to-end communication over the network, managing data flow , error checking and segmentation.
Includes protocols such as TCP and UDP.
Network Layer
Provides the functionality required to transmit data between two different networks including addressing and routiung
Includes protocols such as IP which creates data packets and allows to be delivered
Data Link Layer
Manages data transfer between computers on the same network and handles error detection and correction.
Contains Wi-Fi and ethernet protocols
Physical Layer
Responsible for transmitting raw bits over a physical medium such as cable, fibre optics or wireless
IP packet
Version - IPv4 or IPv6
Time to live - lifespan of the packet to prevent it from circulating indefinitely
IHL - show how many 32-bit words are present in the header
Identification - used to identify fragments of an IP datagram quickly
Protocol - TCP/UDP
Source Address - The IP address of the sender
Destination Address - The IP address of the destination
Data variable - The data
