Paper 2 Flashcards
What a higher-order function?
A function that takes another function as an argument.
Why do rounding errors occur? And what will the system do when the value is converted into binary?
There are not enough bits in the mantissa to represent the value exactly.
It may be truncated- could be rounded to the nearest representable value.
Describe the advantages to using Harvard Architecture:
- Avoids bottlenecking of single data.
- Avoids possibility of data being executed as code (can be exploited by hackers).
- Instructions and data can have different word lengths.
What is the role of interrupts?
Allows the currently executing task to be suspended so that a source that needs the immediate attention of the processor can be serviced.
Why must the volatile environment (the contents of registers) be saved before an interrupt is serviced?
So that the current task can be returned to.
What is the relationship between software and hardware?
Software is the program that executes on the hardware.
What are the principles and operation of an ADC?
- Analogue signals are sampled at regular time intervals.
- Amplitude of analogue waves measured at each sample point.
- Measurement coded into a fixed number of bits.
What are the advantages of floating point?
Can represent numbers with a greater range than a fixed point system (in a given number of bits).
What are the advantages of fixed point?
- Can represent some numbers more precisely than a floating point system.
- Calculations can be performed more quickly.
- Represents all numbers to a constant level of precision.
What are some reasons why JSON could be argued to be better than XML?
- Easier for humans to understand and read.
- More compact.
- Smaller file size.
- Native support for arrays.
- Quicker to parse.
What are some advantages of using the DHCP system?
- Reduces the need for expert knowledge when configuring a host.
- Reduces the time required to configure hosts.
- Avoids errors even as duplicating IP addresses or programming incorrect subnet masks.
How can two or more computers connected to the internet have the same IP address and still communicate with each other?
- The computers have private IP addresses.
- NAT will be performed so that the computers can communicate on the internet:
- As data passes onto the internet, private IP addresses are replaced with public addresses of router.
What are some ways a firewall can protect computers on a LAN?
- Block traffic on specific ports.
- Block traffic from specific IP addresses.
-Block certain types of packet. - Firewall maintains information about current connections and only allows packets relevant to these connection through.
What is meant by immediate addressing?
The operand is the value the instruction should use.
What is the Stored Program Concept?
Machine code instructions stored in main memory are fetched and executed serially by a processor that performs arithmetic and logical operations.
Give the two methods to calculate File Size:
Sample Rate * Sample Resolution * Length of sound
Bit rate * Length of Sound
What are the Principles of operation of an ADC?
- Analogue signals sampled at regular time intervals.
- Amplitude of wave measured at each sample point.
- Measurement coded into a fixed number of bits.
Advantages of Floating point?
Can represent numbers with a greater range than a fixed point system in a given number of bits.
Advantages of Fixed Point?
Can represent some numbers more precisely than a floating point system.
Calculations can be performed more quickly.
Represents all numbers to a constant level of precision.
The computer has 4 gibibytes of memory installed. How many kibibytes is this equivalent to?
1024 x 1024 x 4
Advantages of using Harvard Architecture to Von Neumann arhcitecture?
- Avoids bottlenecking of single data.
- Avoids possibility of data being executed as code (can be exploited by hackers).
- Instruction and data can have different word lengths
What category of system software does a virus checker belong to?
Utilities
Describe two different types of resource management that an operating system is responsible for:
- allocate processes
- allocate memory
Explain how the transport layer of the TCP/IP stack determines which application layer software on the server should deal with a received request?
The transport layer will use the port number to determine which server/software should deal with the request by adding a port number to the request.
Describe the functions of the network layer of the TCP/IP stack:
- adds source IP
- performs routing
- checksum for product header
Explain the key difference between lossless and lossy compression:
Original data can be fully recovered if lossless compression has been used.
Explain how a paragraph of text could be compressed using a dictionary-based method:
A dictionary is built that maps sequences of characters in the text onto values; the sequences of characters in the text are then replaces by the corresponding values in the dictionary.
Explain why dictionary-based compression is not very effective for compressing small amounts of data of text for transmission:
For smaller pieces of text there is little repetition (and so the compressed text will be similar in size to the original).
Describe an example of a problem that could occur if no system were in place to manage concurrent access to the database:
-Two users read and edit the source data simultaneously
- only one data is kept
How does Timestamp Ordering manage concurrent access?
Timestamps are generated for each transaction. Database records timestamp of last read.
Explain what it means for a cipher to be described as being computationally secure:
The cipher cannot be cracked (by any known method) in a polynomial amount of time.
What is thin-client computing and why might it be chosen in preference to thick-client system?
Processing is carried out on an application server.
Clients are cheaper to purchase.
Easier to configure/add a new client.
What is the relationship between bit rate and baud rate?
Bitrate is twice the baud rate
What is the relationship between the bit rate and the bandwidth of the transmission medium that data is transmitted through?
Directly proportional.
Greater the bandwidth, the higher the bit rate.
What is the difference between the operation of serial and parallel transmission?
-serial sends one bit at a time/after each other whereas parallel sends multiple bits simultaneously.
- serial uses a single wire whereas parallel uses multiple wires
Explain why a laser printer with a built-in wireless network adapter is likely to be a suitable choice of printer for a small office?
Why the laser is suitable:
- low cost per printed page (toner is cheaper)
- toner will not dry out
- prints many pages per minute
- high resolution output
Why the wireless adapter is suitable:
- easy to share printer between many devices
- can connect/print directly from computers (no need to install a network to facilitate wireless printing)
- printer can be managed remotely
Describe the principles of operation of a laser printer:
- Bitmap of image built in memory from page descriptor.
- Negative charge applied to photosensitive drum
- laser beam directed at drum
-mirror is used to direct laser beam - when laser strikes drum, charge is neutralised
-negative charge applied to toner
-toner sticks to drum based on charge/where the laser struck
-paper passed over drum and toner transfers to it
-positively charged transfer roller assists transfer of toner from drum to paper
-heater fuses toner onto paper - for colour printing, 4 drums are required.
