| - Directs the flow of data between the CPU and other devices
- Fetch, Decode, Execute | What two tasks are the Control Unit responsible for? |
| - Address Bus
- Data Bus
- Control Bus | What are the 3 buses in a CPU? |
| System Bus | What is the name for the three buses collectively? (Address bus, Data bus, Control bus) |
| A collection of Control Lines | What makes up the Control Bus? |
| Handles commands to other devices | What does the Control Bus do? (generally) |
| Moving data and instructions between system components | What is the Data Bus responsible for? |
| Controls where the Data Bus is going to or from | What does the Address bus control? |
| - Accumulator
- Program Counter
- Current Instruction Register
- Memory Address Register
- Memory Data Register | Name the 5 registers in the CPU |
| Program Counter (PC) | The Address of the NEXT instruction to be executed is held in which register? |
| Current Instruction Register | Which register holds the current instruction being executed? |
| - opcode
- operand | What is the data in the current instruction register divided into? (two things) |
| - Opcode is the part of the instruction which tells the processor what should be done
- Operand is the part of the instruction which contains the data to be acted on, or the memory location of that data | What are opcode and operand? |
| The address of the memory location from which data is to be fetched or written | What is stored in the Memory Address Register? |
| The actual data read from or written to memory | What is stored in the Memory Data Register (MDR)? |
| Memory Buffer Register | What is another name for the Memory Data Register? |
| - Clock Speed
- Number of Cores
- Cache Memory (amount and type) | Name the 3 main factors which affect processor performance |
| 3.5 billion cycles per second | How many cycles per second with a clock speed of 3.5GHz? |
| 2-4GHz | What is the average clock speed? (between two values) |
| Software may not be capable of taking advantage of multiple cores | Why does doubling the number of cores not necessarily double performance? |
| When an instruction is fetched from Main Memory | When is data copied to the cache? |
| Level 1 is faster but smaller | There are different levels of cache - Level 1 and Level 2. Which one is faster and what is the drawback of it? |
| Fetching a new instruction at the same time as the previous is being decoded and executed - performing the different stages of a process in parallel like an assembly line | What is Pipelining? |
| - Instruction Pipeline
- Arithmetic Pipeline | Processor Pipelining is sometimes split into two subs, what are they? |
| A group of bytes | What is a word? (in the context of buses) |
| Harvard | What is the other architecture other than Von Neumann? |
| Digital Signal Processing (DSP) - audio and speech signal processing, sonar etc | What is Harvard Architecture often used for? |
| Harvard Architecture | In which architecture are Data and Programs held in seperate memories? (Von Neumann or Harvard) |
| Data and instructions can be fetched in parallel instead of competing for the same bus | In what way can Harvard architecture be faster than Von Neumann? |
| - Program Counter valuecopied to the Memory Address Register
- Control Unit loads the address onto the address bus and sends a signal to RAM to read the instruction at that address
- Instruction at RAN address is passed across the data bus to the MDR
- Instruction in the MDR is copied to the Current Instruction Register, ready to be decoded
- Program Counter is incremented by one location, ready for next cycle
- Instruction in Current Instruction Register is decoded by the Control Unit
- Executed (usually in the accumulator) | Fetch Decode Execute Cycle |
| - Clock Speed
- Number of Cores
- Cache size
- RAM size
- GPU
- Pipelining | What are the 6 factors which affect CPU performance |
| - Overheating
- Transistors aren't any faster | Why haven't clock speeds increased past 3.5GHz-4GHz? (2 reasons) |
| Heat Sink | What's the bit that keeps the CPU from overheating? |
| - Expensive
- Only improve performance on tasks related to graphics and video
- Use alot of power so might need a more expensive power supply
- Because they use lots of power, they require cooling which is noisy + expensive | List 4 disadvantages of Graphics Cards |
| - Larger and more specific instruction set so programming is simple
- But the hardware is more complex as a result (uses more power) | What is one advantage and one disadvantage of CISC? |
| Simpler instruction set means simpler hardware but more complex software | What is the tradeoff with RISC? |
| RISC because each instruction takes only one clock cycle to complete so tasks can be efficiently scheduled and completed in parallel | Which one is better for pipelining (CISC or RISC) and why? |
| CISC | Which one (RISC or CISC) is usually used in desktop computers and laptops? |
| RISC | Which one (RISC or CISC) is usually used in smartphones? |
| Has several ALUs | What is special about an array processor? |
| GPUs have thousands of smaller, more efficient cores which process in parallel | A CPU has a few cores optimised for sequential processing, what about GPUs? |
| - A co-processor is used to offload compute-intensive parts of an application to the co-processor while the remainder of the code runs on the CPU.
- A GPU is an example of a co-processor | What is a co-processor used for and what is an example of a co-processor? |
| - Pen-type
- Laser Scanners
- CCD readers
- Camera based readers | What are 4 types of barcode scanners? |
| Pen-type readers are the most durable type BUT they need to come into physical contact with what they're reading to work | What type of barcode reader is the most durable and what is the drawback of it? |
| - Barcode Readers
- biometric devices
- sensors | Give 3 examples of automatic input devices? |
| Can store lots of data cheaply but is inconvenient to move around | One advantage and one disadvantage of magentic storage |
| Portable and cheap but small capacity and easily damaged | Two advantages and two disadvantages of optical storage |
| - Backup is a precaution against losing data
- Archiving is storing rarely used data to free up space | What's the difference between backup and archiving? |
| Pits and lands - Pits are burned into the disk's surface with a laser making it less reflective at those points.
pit = 1
land = 0 | How is data stored on optical storage? |
| Blu-Ray has shorter wavelength in the laser which allows much smaller pits to be engraved which means more can be fit in a smaller space | Blu-Ray vs CD ROM - Which has higher capacity and why? |
| They all have a way of representing 1 and 0 without power | What is a similarity between all secondary storage devices? |
| To retain data when the computer is turned off | Why is secondary storage necessary? |
| The platters are coated in magnetic material. The different magnetic poles represent 0s and 1s | How do Hard Disks store data? |
| Use a reflective layer with a transparent dye coating that becomes less reflective when a laser 'burns' a spot in the track | How do recordable disks store data? |
| Use a laser and a magnet to heat a spot on the disk and then set it's state to become a 0 or a 1 using the magnet before it cools again | How do rewritable disks store data? |
| - Fast read/write speed
- Power efficient
- Less fragile
- Silent
- More portable | Name 5 advantages of SSDs |
| - Relatively low capacity
- Expensive | Give 2 disadvantages of SSDs |
| - remove frequencies too high for most people to hear
- remove quiet sounds which happen at the same time as louder sounds | What are 2 lossless compression techniques for audio? |
| Laser scanners | What type of barcode reader is used in supermarkets? |
| Camera-based scanners | What is the most reliable type of barcode reader? (use for Berlin Film Festival Tickets) |
| - RFID (Radio Frequency Identification)
- Passive and Active | What is the technology used for oyster cards and what are the two types? |
| Dog tagging | What is another use of RFID tags other than bank cards/oyster cards? |
| OLED is plastic so it can bend | What's the difference between LED and OLED screens? |
| - don't last as long
- sensitive to water
- slow refresh rate (bad for games) | What are 3 disadvantages of OLED displays? |
| - Thinner
- Don't need backlighting
- Consume less power | What are 3 advantages of OLED displays? |
| - they're decent quality and FAST
- They use toner as ink | What's the good thing about laser printers and what type of ink do they used? |
| - Inkjet
- Works by spraying minute dots on the page | What type of printer is very high quality and how does it work? |
| Moving an aileron | What is a use of an actuator in the context of a plane? |
| Blu-Ray has shorter wavelength in the laser which allows much smaller pits to be engraved which means more can be fit in a smaller space - higher capacity | Which has higher capacity and why? (CD-ROM or Blu-Ray) |
| - Bootstrap loader
- a small program that starts up as soon as the computer is switched on and causes the OS to be loaded | What is something which is stored in ROM and what does it do? |
