# Scholar homework session – Wednesday 28th Jan, 7.30pm

Ian King will be running a Scholar homework session this Wednesday 28th Jan at 7.30 pm til around 8.15.

The topic is Storing numeric data (binary, two’s complement and floating point notation)

You can access the session, which will last about an hour at

# CS Revision Topics

• Binary
• Bit Mapped Graphics
• Buffers
• Calculation of Graphic Image sizes
• Calculation of Memory Capacity
• Comparison of backing stores
• Computer Performance
• Floating Point Notation
• Network Servers
• Network Speed
• Printer Interfaces
• Printer Spooler
• Technical characteristics of printers
• Topics for Revision
• Two’s Complement

# Homework w/b 15th Dec

## Networking

Q1 Explain the difference between LAN’s and WAN’s with reference to transmission media, bandwidths and geographical spread. (2)
Q2 Explain the difference between a mainframe computer with terminals and a network of computers. (2)
Q3 Explain the differences between client server and peer-to-peer networks. (2)
Q4 On a LAN describe the functions of file, print and web servers. (2)
Q5 Describe a bus topology in terms of nodes and channels. Describe the consequences of failure of a node and a channel. (2)
Q6 Describe the functions of a hub, switch and router on a network with particular reference to the differences between a hub and a switch. (3)
Q7 Explain why a network computer needs a network interface card (NIC). (1)
Q8 Explain briefly why networks are becoming increasingly widespread. (2)
Q9 Explain how a virus may be spread to a computer and how it then may take effect. (2)
Q10 The access a user has on the network depends on their permissions. Explain what is meant by permissions giving as an example the permissions you may have on your own folder and a shared folder on the network. (2)

Total Marks – 20

# Homework – Topic 4 – Peripherals

Q1 A peripheral device captures colour images and saves them to memory.
a) Describe how the colour is represented using 24 bits (1)
b) The image is saved with a resolution of 600 dpi. How many pixels are required to save an image of 6” x 4”. Give your answer in MB and show your working. (2)
Q2 Explain how a buffer is used with a peripheral. (2)
Q3 Explain the concept of spooling illustrating your answer with an example. (2)
Q4 State the hardware required in terms of peripherals to set up a computer system to produce a catalogue for a garden centre. The finished catalogue will be taken on electronic media to a printers. (2)
Q5 Justify the choice of two of these devices in terms of resolution, capacity, speed, cost and compatibility. (4)
Q6 Describe the features, uses and advantages of a solid state device such as a USB flash drive. (2)
Q7 a) What is the purpose of an interface? (1)
b) State the factors that have to be resolved by an interface. (2)
Q8 Describe the difference between parallel and serial interfaces (2)
Total marks 20

# Homework Topic 3 – Measuring Performance

Q1 What factors can influence the MIP rate of measuring performance? 2
Q2 Explain what is meant by the cycle time with reference to the clock speed. 2
Q3 Explain why two computers rated at the same clock speed may not have an equivalent performance.2
Q4 Explain what is meant by a benchmark test in measuring a computer’s performance and give an example of one such benchmark. 2
Q5 Explain the effect of the width of the data bus on a computer’s performance. 2
Q6 Why is an interface needed to connect peripherals to the system bus? 2
Q7 Describe the standard functions of an interface. 2
Q8 Explain the difference between serial and parallel transmission. 2
Q9 Explain why the increase in the width of the data bus can improve system performance. 2
Q10 Explain why the increase in the width of the address bus can improve system performance. 2
Total Marks 20

# Fetch Execute Cycle

I was asked for more detail about the fetch execute cycle. So I thought I would look for something new and a simpler way to explain it.  So if you have a look at this BBC page,  you should get a basic overview of what is happening. You can then read what I found on this page, this will help you to understand it a little better.

Then you can read my blog post about it, which also includes a link to an animation.

# Spring break – Revision

Use the 3 documents below to create a set of your own revision notes. You might want to use books, notes, presentations or the scholar website to help you.

Don’t copy and paste from the Internet. type each one out by hand.

# Answers to today’s Starter Questions

These were taken from the 2008 Section 1.

1a(i)Describe how bit-mapped images are stored. 1 KU
• An array/grid of pixels
• Each dot/pixel has a binary value
• Each pixel stored as a bit/byte/binary value/black=1 & white=0
• Accept black=1 and white=0 type answer but not the colour of each pixel
• Any one from above 1 mark (Not “the colour of pixels are stored” or “individual pixels” or “pixel by pixel”)

1a(ii) Describe how vector images are stored. 1 KU

• As a number/list of objects (each of which has attributes defining the objects)
• Objects are defined by attributes/mathematical description
• Accept an example object used to describe eg rectangle and attributes
• Any other valid
• 1 mark for any of the above

1b Is the above image bit-mapped or vector? Justify your answer.2 PS

• Bit-mapped (1 mark)
• Composed of grid of (individual) pixels
• Does not contain/is not comprised of (collection of discrete) objects
• It is pixelated
• It is a photograph/taken with a digital camera
• 1 mark for any valid bullet point (Not painting or resized)

2a Explain how the heuristic detection technique is used to detect a virus.1 KU

• It looks for a suspicious pattern of behaviour (which was previously associated with a virus)
• Accept use of a valid example to illustrate concept
• Any other valid
• 1 mark

2b Explain why a trojan horse is not classified as a computer virus. 1 PS

• A trojan horse is not self replicating
• Does not infect other files
• 1 mark for any one of the above (do not accept a description of what a trojan horse does)