Answers to Sample Questions

Lecture 2: Look out! it's the future

You could answer this three ways, all acceptable - you could go for the hardware and say that early research machines were followed in turn by large business mainframes, then minicomputers and PCs. Next in line come wearable or pervasive computers.

You could concentrate on the users and say that computing moved from military to scientific then corporate business to personal use with the next stage being pervasive computing. I would accept the Internet as a major stage.

The question is designed to let you demonstrate that you have a good concept of the history of computing and current trends.

 
2.2. What is Moore's Law and what effect is it likely to have on average processor speed over 10-15 years?

It is generally taken to be that computer power and capacity doubles every 18 months. I would accept 18 months or 2 years here. In 10-15 years that represents a factor of 1000 increase - 15 is 10 lots of 18 months so is an increase of 2^10 = 1024 or thereabouts. If you had said 2 years then you're looking at (say) 6 lots of 2 years and 2^6 is 64. The point of the question is to show you have some concept of therapid rate of increase in speed.

 
2.3. Name three reasons why new technological products are being taken up faster and faster

Straight from the slide: Technology products are getting cheaper, income is greater, new industries are flexible and can create new products quickly.

 
2.4. What does not obey Moore's law? What effect is this likely to have on the nature of products we buy?

People's skill and time gets more expensive and does not speed up. The result is a shift towards bundling a service with sale of hardware as a ccompany can't make a profit on hardware alone.

Lecture 3: Back to fundamentals

A byte is a collection of 8 bits so 2 to the power 8, i.e. 256.

 
3.1. The character 'o' is represented in a computer by the hexadecimal number 6f₁₆. What hexadecimal number is likely to represent 'p' ?

70. Count on your fingers, remembering that digits go 0,1, ...9,a,b, ... f, 0

 
3.2. A 20 Gb disk is backed up to 250 Mb ZIP disks.

1. How many ZIP disks might be needed?

   20,000 Mb divided by 250 Mb = 80

2. In the light of (1.) would you choose to back up the disk this way and if not what might be a better alternative?

   Not if it could be helped. For backing up a complete disc (presumably to guard against catastrophic failure) a high capacity tape drive would normally be used. Even a CD-writer would require 30 CDs which could not be re-used

 
3.3. You are provided with two brand-new (empty) 250 Mb ZIP disks, one with 2.5Mb of free space left on it, one with 25Mb left on it and a couple of 80 Gb tapes (with suitable software and hardware)

Making best use of the media you have, how would you store the following:

1. An 8-page essay
2. An on-line copy of the Edinburgh telephone directory
3. A 3 minute album track recorded as MP3
4. Backup of the hard disk of a medium-sized desktop PC bought in 2000/2001
5. Backup of a full CD-ROM

The essay will be say 30 Kb, the telephone directory 20 Mb, the album track 2-3 Mb, a current hard disc could be anything between 20 and 50 Mb and a CD-ROM would be 650 Mb. Back the disk up to tape, ditto the CD-ROM. The telephone directory would go on a new ZIP and the essay would fit in the spare space on the nearly-full ZIP. The question is designed to see if you have some concept of how big things are.

 
3.4. What problem might a mail system encounter sending the following phrase and how would it deal with it?

"We'll meet Françoise outside the cinema at 7:45. Tickets are £5.00"

The pound sign and the Cedilla would need to be quoted by the mail system to avoid them being mangled en route.

 
3.5. Two lines in a mail header read:

Content-Type: image/gif
Content-Transfer-Encoding: base64

• What is the mail sender doing here?
• What is likely to follow these lines?

The mailer has encoded a binary attachment (in this case a GIF image) for transmission using MIME encoding. The header tells the far end that what follows is a GIF image, encoded as base-64.

What follows will be a whole lot of lines of hexadecimal

Lecture 4: Inside the box

a) Purely on the basis of advances in processor speed approximately what fraction of the speed of a current model would you expect from a 2-year-old machine?

Moores' law (speed doubling every 18 months, remember?) - about a factor of 3. I'd accept anything between 2 and 4. I would probably ask you to justify your answer in this way.

b) What other factors might be contributing to the machine's poor performance?

Most likely lack of RAM memory relative to what she was doing with it but possibly a very full hard disk. Unsuitable applications (something very graphics- or compute-intensive intended for a modern PC or one with an accelerated graphics card; slow network performance or a slow Web server somewhere (she isn't specific).

c) Your friend reports that her son is wanting to use the machine for game playing and is finding it impossibly slow. What upgrade might improve matters for him?

A good graphics card might be a good start.

 
4.2. Name four things you might expect to find plugged into a computer mother board.

Hmm, not a very good question now I look at it. Processor, Graphics card, ether card, RAM, IDE cable to hard disk or CD-ROM, cable to floppy ...

 
4.3. 'Part B' question: What are the principal points you need to consider when specifying and buying a PC?

Lecture 5: Beyond the box

 
Large corporate system, fairly fixed pattern of use supporting a few key applications such as transaction processing (bank, building society, travel agent) or database (investment bank) 5.2. Describe the principal characteristics of a server One of a number of similar 'peer' computers offering service to clients e.g. file service, mail, printing or a particular application.

 
5.4. Compare and contrast the principal aspects of a laptop versus a desktop PC Laptop: portability at the expense ease of use (flat keyboard, pad or ball instead of mouse, flat, smaller screen); also difficult or expensive to expand and repair

Desktop PC: the opposite - fixed location, a 'kit of bits' so if one goes wrong a unit can be swapped in, can have large screen, specialised peripherals, ergonomic keyboard

 
5.5. What design constraints need to be considered by manufacturers of PDAs ?

Can't have a keyboard so need voice or stylus input; Small display so need highly customised applications

 
5.6. A friend is about to purchase an upmarket digital camera capable of taking pictures at a resolution of up to 2400 * 1800 pixels. The intended purpose is for taking photographs for their web page. Why might this not be the best use of their money? Your friend goes on to say that the web page is entitled 'Vanishing Edinburgh'. Would this change your advice in any way?

It is much higher resolution than is needed for a Web page and unless they are zooming into tiny parts of the picture the images will have to be cut down in resolution. Technology will change and higher resolution will become cheaper so if you don't need it it is a waste of money.

If the pictures are 'archival' however and need to stand the test of time then it is an argument for higher resolution as in a few years networks will be faster and screens have higher resolution and higher resolution images woukld be the norm. If the subject has vanished you won't be able to retake the photo. Actuallly in this case I would advise taking ordinary photos with a good camera then scanning them.

 
5.7. It is possible to use a terrible phone line and still be understood yet sound is probably the main limiting factor in videoconferencing applications. Explain this apparent contradiction.

It depends on the meaning of 'terrible'. Poor analogue phone lines are generally noisy (which the ear can deal with). Digital voice channels tend to break up with the loss of chunks of sound which the brain has difficulty working around. Videoconferencing

Lecture 6: Standalone Applications and Presentation Graphics

 
6.2. 'Part B' question: Modern computer applications offer the user many opportunities and without them many large problems would be insoluble. Describe some of the ways in which applications are applied in the world of work and and some of the dangers.

 
6.3. What aspects of a complex but well-designed application would make it easy to learn?

Intuitively obvious, good use of meaningful icons, on-line help and tutorials, consistent style, style that matches accepted conventions elsewhere, etc.

Lecture 7: Text editing and Word processing

a) because not everyone wants to go and buy Lotus / Word
b) Because it is often necessary to edit plain ext files and functionally rich word processing applications just get in the way or could end up with you writing the file back in a format you didn't intend.

 
7.2. What special features would you expect to find in an application advertised as a Word Processor?

Check out the slide: lots of fonts, styles, indexing, tab and paragraph handling, just recall what's in the top menu of any word processor and write it down.

 
7.3. Identify the main features of a Word processor that relate to document style another flaky question now I look at it. Margins, line spacing, fonts, heading sets, etc.

 
7.4. Fixed pitch fonts such as Courier are not particularly attractive. Why are they useful?

Because anything imported as plain text retains its format - a column of figures will stay lined up. If there's a variable pitch font they'll end up all over the place. Was this in lectures? can't rcall.

 
7.5. Identify the stages in producing a piece of creative technical writing. Why might use of a word processor actually be a disadvantage? (Reworded, this could be a part 'B' question)

 
7.6. What is a FOG index and how might it aid creative writing? It is a measure of the complexity of a piece of text based on word and sentence length. It allows one to review something one has written and make it simpler.

 
7.7. Identify the principal differences between a text editor, word processor and a high-end professional desktop publishing package

Lecture 8: The Operating System

Symptom is therefore lots of hard disk activity whenever the computer is asked to do anything, way beond what you would expect from it simply pulling in data or program files.

Solution is (immediately) to kill off as many inessential programs as possible. Longer-term solution is to add more memory (RAM).

8.2. Describe one way in which a rogue program can completely hang a PC.

It could demand huge amounts of virtual memory. If it went into a tight loop repating the same small sequence over and over it might hang the PC.
8.3. Identify some of the functions of a scheduler

Lecture 9: Spreadsheets etc.

9.1. In the spreadsheet above, the formula "=A1*D1" was entered in cell B1 and dragged downwards. In column f(B) write in the formulae that would be generated and write the calculated values into cells B2:B4

Similarly, the formula "=A1*D$1" was entered in C1 and dragged down. In column f(C) write in the formulae generated and write the calculated values into C1:C3.

Lecture 10: Spreadsheets and decision support

Lecture 11: Files and data

It is virtually impossible to completely destroy a file once it has been written. Just deleting it and even reformatting the disk is not enough (and forensic programs can even recover files that have been overwritten with new data). It is safer to destroy the disk.

 
11.2. What is disk fragmentation and how might it adversely affect the performance of a PC?

It is when it is no longer possible to write files in a single extent ('chunk', whatever you like) on the disk and instead bits of the file are written wherever they will fit and linked together. The result is that the disk heads have to move all over the disk fetching these fragments and a lot of unwanted disk head activity that slows everything down.

 
11.3. A web page carries a practically full-screen image of 800 * 500 pixels with 24 bits per pixel.

a) How much data does this image represent?
b) A domestic modem can transmit of the order of 4 kilobytes / second. How long would it take to download the amount of data you calculated in a) ?
c) Web pages with full-screen images are common and download over modems perfectly satisfactorily. How do you explain this apparent contradiction?

a) 800 * 500 * 3 bytes = 1200000 bytes = 1200Kb
b) 1200 Kb / 4 Kb/second = 300 seconds = 5 minutes
c) Because they use compressed formats such as JPG to dramatically reduce the data needed for an acceptable image

 
11.4. What image formats (GIF, JPG, TIFF, BMP etc.) might you select to store:
a) a diagram for display on a web page?
b) A scanned image of an oil painting for inclusion in a book?
c) A scanned image of the same oil painting for inclusion in a web page?
d) Holiday snaps for a home web page?

a) GIF. Diagrams don't usually contain more than 256 colours (the max. for GIF) and GIF is lossless - edges of lines remain sharp. JPG can make them lose definition.
b) TIFF. You want true colours, maximum resolution, lossless and a painting will be difficult to re-scan as you'll have to make arrangements to access it, clear copyright etc. so you want the best image you can get.
c) JPEG from a TIFF original. You don't need resolution but you do need it small. Arguments in (c) apply. Browsers won't display TIFF
d) JPEG (or Kodak-CD if you're aware of it)

 
11.5. Describe the main weakness of single-key encryption systems and one drawback of dual-key systems.

single: You have to tell the recipient the pass key somehow.
dual: You have to trust that the published public key is the true one - if I could subvert the published version of your public key I could fool someone into sending material encoded with my key which I could read. If that melts your brain a simpler answer is that you can't publish material for more than one recipient - you'ld have to publish loads of copies, one per person you wanted to send it to.

Lecture 12: Applications of Computer Graphics

Lecture 13: Databases and GIS

Edinburgh branch Catalogue no. Manufacturer's part no. stock checked No. in stock F101 Zetec/30021101/5/A800 26/10/00 12 F102 Zetec/30201101/5/A800 27/11/00 8 K403 Zetec/30021101/6/A800 27/11/00 4

Glasgow branch Catalogue no. Manufacturer's part no. stock checked No. in stock F101 Zetec/30021101/5/A800 24/07/00 1 K304 Zetec/30201101/5/C800 26/09/00 2 K305 Ford2.7/30021101/6/A800 26/09/00 6

Parts directory

Catalogue No. is the primary key.

a) List the catalogue numbers of the intersection of the two relations.

The item(s) that appear in both relations - F101

b) List the catalogue numbers of the Union of the two relations

The items that appear in both relations taken together, listed once only - F101, F102, K304, K305, K403

c) Which column headings and primary key values would appear in an inner join of "Edinburgh branch" and "Parts Directory" ? The only join I told you about was the inner join but i should have phrased that slightly differently. Anyway, it is Catalogue No., Manufacturer's part no., description, inventory value, re-order quantity, stock checked, no. in stock

Lecture 14a: Databases / 14b: File storage and media

Lecture 15: Human factors

Lecture 16: Collaborative computing

• Faster than post about the same or slower than fax or text messaging
• Less formal than a written letter
• Easier to compose than a text message
• Less immediate feedback than a phone call
• Easier to handle across timezones than phone
• etc.

 
16.2. What is a smiley and why would it be used?

A graphic composed :-) or similar used to indicate that what came before it should not be taken entirely seriously. Used as a substitute for expression in a face to face conversation

 
16.3. The project team of an engineering firm in Essex elects use a video conferencing circuit to discuss engineering drawings with its clients in Germany. There are five members of each team and they use purpose-built video conferencing studios for the call. Each end of the call has a monitor equivalent in quality to an 800*600 PC monitor, a steerable video camera, microphone and speakers. What benefits and difficulties do you think the teams will encounter compared to meeting face to face?

Two obvious difficulties are that the 800*600 resolution won't be enough to relay any fine detail such as an engineering drawing and that you will not get eye contact in a studio setting like this. Other points are that with 6 possible points of interest (5 people and any drawings etc.) you may need someone just steering the camera full time or you'll not be showing the person speaking. You may have difficulty managing the meeting so people don't cut across each other etc. etc.

The benefits are that for most (not all) meetings you can avoid having to fly the team from Essex to Germany (I had Ford at Laindon and Cologne in mind when I wrote this - they actually ran their own charter shuttle between those cities till they installed video studios)

Lecture 18: Managing Machines

Lecture 19: The World-Wide Web

By collecting all the style information in one place one change will be inherited by every page that uses the Style Sheet thus dramatically reducing the effort needed to update a web site

 
19.2. The next major step in the development of thew Web is likely to be the transmission of meaning as opposed to information. Give an example of where the automatic exchange of meaning could transform an aspect of business or employment.

I think the example I used in lectures was a recruitment agency - instead of sending in plain text CVs you would send in an XML version of your CV which would be matched against equivalent postings from firms with vacancies. Another one would be a procurement process where again a request would go out to tender for some item and be automatically matched with catalogues of potential suppliers.

Lecture 21: Web site Function, Style and Content

Lecture 22: Web page Creation

Initially, ease of use - content could be reached by just clicking a mouse. The fact that it is a machine-independent, vendor-independent standard is one; It has the functionality needed. Maybe not my finest question.

A Comms question

The answer is straight from the notes. Another version of the question could ask for 2 functions but requiring some additional information for 4 marks.

A programming question

I am looking for references to recipe as guidelines open to interpretation by cook, using experience and common sense whereas program must be completely specified and then ingredients/information - actions - flow of control etc.

Part 'B' algorithms question