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ALU
Made up of several components; performs any arithmetic calculations (e.g adding binary) or any logic comparisons (using AND, OR, NOT).
Control Unit
Coordinates all of the components inside the CPU. It is where instructions are decoded; controls the data within the CPU and how it moves around.
Program Counter (PC)
Stores the address in memory of the next instruction to be fetched.
Accumulator
This is where values are stored temporarily, either after they've been inputted or loaded, or after being calculated in the ALU.
Memory Data Register (MDR)
Temporarily stores the data/instructions after being fetched from memory or before being sent to memory.
Memory Address Register (MAR)
This is where addresses are stored, either for where data is being sent in memory, or where it is being fetched from.
Current Instruction Register (CIR)
When an instructions has been fetched from memory it is loaded here in CIR before being split into opcode(what the instruction actually is) and operand(where the instruction has to be carried out). After this, it will be decoded.
ALU: Arithmetic Circuit
Carries out any arithmetic(addition, subtraction, multiplication, division).
ALU: Logic Circuit
Carries out operations like AND, OR, NOT, XOR.
ALU: Registers
These are additional registers to those in CPU and can store data.
ALU: Status Flags
This includes overflow flags(if the value is too large from the register) or would include a zero flag (to tell if the answer is 0 easily) .
Data Bus
Holds data being sent to/from the CPU and RAM.
Read/Write; Bi-directional
Address Bus
Holds addresses being sent to/from the CPU and RAM.
Read/Write; Data is only sent in one direction
Control Bus
Sends signals to determine whether the other buses are in read or write mode.
Sends signals; Bi-directional
Which factors improve CPU function?
Bus size
Cache size
Number of cores
Clock speed
Word length
Pipelining
What is pipelining?
Pipelining is the technique of fetching an instruction whilst the prior one is being decoded and the one before that is being executed.
How does pipelining improve processor performance?
Pipelining increases the efficiency of the CPU components by ensuring that none are left idle. It also allows multiple instructions to be executed simultaneously, which improves performance.
Clock
It coordinates all of the actions inside the CPU. With one tick, one instruction is processed. Increasing the speed of the clock increases the number of instructions that can be processed per second.
Why does the CPU clock have an upper limit that it can comfortably run?
The CPU has an upper limit of 4GHz because to make the clock tick, a bit of power is generated and that power generates heat, which can slow down the processor and decrease its efficiency.
What is overclocking and why may people want to overclock their CPU?
Overclocking is when a CPU runs faster than its normal design speed. Some gamers may want to overclock heir CPU to stream/run games faster and load more/high-quality graphics.
How can you overclock a CPU without damaging the CPU chip?
You can overclock a CPU without damaging the chip by cooling it , e.g. by having a water cooled computer, or a liquid nitrogen cooled one.
Core
It is a complete processing unit within the CPU with an ALU, CU and registers.
How does number of cores improve performance?
Increasing the number of cores can allow the CPU to do multitasking or parallel processing, and run more than one task simultaneously.
What is multitasking?
Running more than one task simultaneously; each core doing a different task.
What is parallel processing?
When a single task is split into two or more parts and each part is processed at the same time. This could double performance as each part is processed independently ( e.g. on a dual core CPU).
Explain why parallel processing won’t necessarily lead to an improvement in CPU performance.
Most programs cannot be split neatly into two parts that are independent, since they are mostly sequential. Parallel processing is possible in individual tasks where each task doesn’t depend on another task.
Cache
It is a small, extremely fast type of RAM located inside the CPU chip itself. It is much faster to access than RAM.
Why does a larger cache speed up processing time?
RAM is relatively slow to access compared to the speed of cache or registers. Cache memory is used to store instructions or data that are either frequently used, have recently been used or are about to be used so that they don’t have to be fetched directly from RAM. A larger cache means that more instructions and data can be stored close to the CPU, and so it takes less time to be fetched, which increases the speed of the processor.
Why is there usually a limit to how much cache is in a computer system?
Cache is much more expensive than standard RAM, and it has a much more smaller capacity than RAM.
RAM
RAM is the main memory that is used to store computer programs and data currently in use. For a computer to operate smoothly, you need enough RAM.
Virtual Memory
An area set aside on the hard disk to act as a slow form of RAM. It will be used to store some of the currently running programs and data if RAM is full.
Why will a computer appear to run slowly if it doesn’t have sufficient RAM?
If RAM is full, virtual memory will be used, which is much slower than RAM. If the computer doesn’t have enough RAM, then virtual memory will be used heavily, so the computer will seem to be running very slowly.
Why will adding excess RAM not improve the performance of a computer system?
The extra RAM will go unused.
Explain how installing a graphics card can help improve the performance of a system that is running a video game.
Video games usually contain 3D graphics, which require a lot of processing power. Therefore, gamers may install a specialist graphics card containing a "Graphics Processing Unit" or GPU which is designed to handle graphics and video much faster than the CPU itself. If an application is making intense use of graphics or video then installing a GPU will improve performance considerably as the CPU will send any graphics related tasks directly to the GPU while it continues to process other tasks.
Issues of installing a graphics card
Can be expensive
Do not improve CPU performance on all tasks, only ones related to graphics and video
Use a lot of power: this might mean that the computer will also need to be fitted with a more powerful power supply, which will add further cost.
Because they use a lot of power, they also need a cooling fan, which are noisy so they make the computer sound louder than they were before the graphics card was installed.
Von Neumann architecture
Used in PCs, laptops, servers and high performance computers
One bus is simpler for control unit design
Data and instructions share the same memory. Both use the same word length
One bus for data and instructions can lead to a bottleneck
Harvard architecture
Used in digital signal processing, microcontrollers and in embedded systems such as microwave ovens and watches
Instructions and data are held in separate memories which may have different word lengths. Free data memory can’t be used for instructions, and vice versa
Control unit for two buses is more complicated and expensive (more hardware required)
Separate buses allow parallel access to data and instructions
RISC (Reduced Instruction Set Computer)
Simple hardware
Further away from high level languages
Compiler has to do more work
Every operation takes place in one clock cycle (allows for pipelining- more efficiency)
Longer code requiring more RAM
CISC (Complex Instruction Set Computer)
More complex hardware
Closer to high level language
Less work for the compiler to do
Some instructions take multiple clock cycles to complete
CPU vs GPU
| CPU | GPU |
Function | Generalized component that deals with the main processing functions of a computer. | Specialized component that is great for parallel computing |
Processing | Runs processes serially | Runs processes in parallel |
Design | Fewer more powerful cores
| More cores (less powerful than CPU cores) |
Emphasis | Low latency (delay) | High throughput |
Uses | General purpose computing devices | High performance computing devices |
Why can GPU never fully replace CPU?
CPUs are ideal for performing sequential tasks
GPUs use parallel processing
Four main types of barcode readers
Pen-type readers, laser scanners, CCD readers and camera-based readers
Which type of barcode stores the most information?
2D barcodes, such as QR codes.
Which type of reader is most typically used for reading 2D/QR codes?
A camera-based imaging scanner uses a camera and image processing techniques to decode a 2D barcode.
Which type of barcode scanner is the most durable and why?
Pen-type scanners because of their simple design, and they can be tightly sealed against dust, dirt and other environmental hazards.
A digital camera uses a CCD or CMOS sensor. Describe how they work.
The sensor is comprised of millions of tiny light sensors arranged in a grid. The binary data from each sensor is recorded onto the camera's memory so that the image can be reproduced using suitable software at a computer.
Suggest a suitable sensor type for use in a mobile phone camera and give a reason why.
While CCD sensors produce higher quality images and are used in higher quality cameras, a CMOS sensor would be better for a mobile phone camera as they consume up to 100 times less power. This makes the phone battery last longer as it uses less power to take photos, and also makes the phone faster as it uses less processing power to take photos. It is also cheaper, so it reduces the overall cost of a phone.
How does a passive RFID chip work?
Sensor pad emits radio energy
RFID antenna picks up radio waves
RFID chip becomes energised
RFID chip is able to send identification data
RFID chip is able to receive updated data
Difference between passive and active RFID tags
Active tags are physically larger as they include a battery to power the tag so it actively transmits the signal for a reader to pick up. Passive tags are much cheaper to produce as they do not have a battery.
Uses of RFID tags
Identifying pets, contactless bank cards, tracking cars as they pass through a motorway etc.
SSD vs HDD
Characteristic | SSD | HDD |
Speed | Faster than HDD | Slower |
Capacity | Similar capacity | HDD may have slightly more |
Durability | Has no moving parts More durable, lasts as long as HDD | Moving parts may be broken easily 3-5 years |
Portability | More portable; small and lightweight | Very heavy and hard to transport around |
Expense | Much more expensive | Much cheaper per GB |
Key differences between RAM and ROM
RAM is primary storage that is volatile. It is used to hold current programs and instructions that are being used by the computer.
ROM is read-only memory secondary storage that is non-volatile. It is used to hold bootstrap instructions.
Logical storage vs physical storage
Logical storage is storage that is formatted by an operating system, whereas physical storage is based on the storage capacity of the hardware.
Benefits vs Drawbacks of Virtual Storage
Benefits | Drawbacks |
Easier to manage as it is done via a central console | Requires an internet connection |
Flexible storage options | Most providers require a subscription |
Less hardware- cheaper costs | Privacy concerns- security depends on the cloud storage provider
|
Users do not easily lose access to all data if device lost |
|
More widely accessed- portable |
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6/8 MARKER: You are designing a new laptop for a graphic design professional. What storage configuration would you recommend and why? Consider factors like speed, capacity and reliability. (PRIMARY STORAGE PART 1)
Primary storage:
TYPE: SSD- 1TB/2TB
SSD offers fastest read and write speeds, which significantly improves overall system responsiveness, especially when working with large files and running intensive software such as Adobe Photoshop, Illustrator or 3D rendering programs. A 1TB capacity is ideal for most users, providing plenty of space for operating systems, applications, and active project files without running out of room quickly, A 2TB drive would be beneficial for those working on large project simultaneously.
6/8 MARKER: You are designing a new laptop for a graphic design professional. What storage configuration would you recommend and why? Consider factors like speed, capacity and reliability. (SECONDARY STORAGE PART 2)
Secondary Storage:
TYPE: An external SSD/HDD or External Storage for Archiving- 2TB or more
A secondary drive is useful for string completed projects, backups, and files that are not used daily. An external SSD or HDD could serve this purpose well, offering flexibility and expandability, which is ideal for archiving projects without cluttering up the primary storage.
6/8 MARKER: You are designing a new laptop for a graphic design professional. What storage configuration would you recommend and why? Consider factors like speed, capacity and reliability. (CLOUD/BACKUP STORAGE PART 3)
Cloud Storage Backup Integration:
TYPE: Cloud Service like Google Drive, Dropbox or Adobe Creative Cloud. At least 1TB or more.
Cloud Service adds an essential layer of redundancy, ensuring that critical work is backed up and accessible from anywhere. This is particularly valuable for remote collaboration or accessing older projects when away from the main device.
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