Storage characteristics and trends

Questions

1. What does 'random access' mean?
Random access means that any storage location can be directly read or written. It is also called 'direct' access.

2. What does 'sequential access' mean?
Sequential access means that the storage locations have to be read or written in their correct order, starting with the first location.

3. What does 'volatile' mean?
Volatile refers to storage devices that will lose all thier data if the power is switched off.

4. Why is RAM the only volatile storage device?
RAM is the only storage device that can described as volatile as it needs a contant power supply to keep its data.

5. Why are sequential access devices better suited for storing backup data?
They work at a slow speed. Although access times may be poor, the rate of continuously writing or reading data can actually be very fast.

Storing and Retrieving hardware

RAM and ROM

RAM (Random Access Memory)- is needed in any system that needs to store new instructions and new data, or to change those instructions or data. RAM chips are primary storage devices found in every computer system.

The most common forms of RAM include:

• DRAM (Dynamic RAM)- cheapest and the slowest, uses transistor and capacitor, needs regualr refreshing [used in main system memory]
• SRAM (Static RAM)- faster but more expensive than DRAM, does not use capacitor [built in CPU]
• EDO (Extended Data-Out) RAM- allows more than one memory location to be accessed at the same time, speeds up data access [Main system memory]
• SDRAM (Synchronous DRAM)- most common RAM in desktop PCs [Main system memory]
• RDRAM (Rambus DRAM)- uses a high speed data bus to access memory locations, needs a specially designed motherboard [Main system memory]
• VRAM (Video RAM)- High speed RAM used to hold graphics data including 3D models and textures [3D accelerator graphics cards]
• Flash RAM

ROM (Read Only Memory)- memory whose content can be accessed and read but cannot be altered. Used for BIOS (on the ROM chip)- helps load the system

Varieties of ROM:

• ROM- Permanent data storage [can be found in singing birthday candles and musical greeting cards]
• PROM (Programmable ROM) - Permanent data storage. Data is added on to the blank ROM chips by a 'burning in' process. Easily damaged by static electric charges [used in security systems that need to prevent any alteration of data e.e. smart ID cards]
• EPROM (Erasable Programmable ROM)- Data can be erased by exposing the chip to ultraviolet light. New data can then be added
• EEPROM (Electronically Erasable Programmable ROM)- Data can easily altered without the need for special equipment or to remove the chip [used in cash registers, computer BIOS]
• Flash memory

Magnetic Storage Devices

• Common magnetic storage devices are tapes, hard disks and floppy disks.
• Magnetic tape is still commonly used for storing backup data
• Disks are organised into tracks and sectors that hold the data
• Saving a file involves filling up a disk sector and recording the location of each sector used
• Disk formatting prepares the surface to receive data

Optical storage devices

• The term 'disc' is commonly used for optical storage devicws while 'disk' is used for magnetic devices
• 'CD' stands for Compact Disc
• CD-R technology uses a coloured dye that can be changed by heating to permanently record data
• CD-RW technology uses a dye that can be swtiched between cloudy and transparent
• DVDs (Digital Versatile Discs) can store data on two separate laters on both surfaces of the disc

Assess optical storage as a possible replacement for magnetic storage devices.
Optical storage devices can store a large quantity of data and cost very little to manufacture. If low portable storage is needed, then CD-Rws are probably better value than floppy disks. However, the do not match a hard disk for speed and storage capacity. If high capacity, high speed storage is needed, then hard disks are still a better choice than optical storage devices.

Questions
1. What is the most common type of RAM used in computers?
SDRAM (Synchronous Dynamic RAM)

• uses bursts of higher speed to read the individual data bits once it has located the memory address

2. What makes EEPROM the most useful of the ROM type of memories?
The data on EEPROM can be easily altered without the need for special equipment or to remove the chip. It provides a convenient way to allow permanently stored instructions to be upgraded.

3. Optical storage devices store data as light- true or false?
False.

4. Why would PROM be an ideal storage device for security data?
Security data would usually require prevention of any alteration to the data. Having blank chips where security data can be added to and not altered makes PROM an ideal storage device for this type of data.

5. Give examples of situations where CD-R is a better choice for data storage than CD-RW

• When handing in a final assignment to a teacher, having data that cannot be altered by anyone on the disc
• When storing textbook information on a disc

6. 3.5 inch floppy disks have changed very little since they were first introduced in the mid 1980s- that makes them old technology. Give some reasons for their continued popularity.

• compact
• light
• portable
• removable data

7. Assess the advantages and disadvantages of flash storage devices as replacements for floppy disks.

Advantages

• has a higher storage capacity
• fast and does not require any power to keep data in storage
• portable (small size)

Disadvantages

• requires a small electric current to 'remember' its stored data

SSD- Solid State Drives: Instead of using a hard disk drive, it uses flash memory; permanently located inside the computer, secondary storage. Advs: fast, no moving parts to crash,

Manipulating Video and Audio Data

Project File: A file created by Xcode that organizes source code, resources and settings used to build a product

• Is saved with a .wlmp file name extension
• Contains information about the arrangement and timing of photos, videos, text, muic, transitions, and effects that are used in the current project and appear on the storyboard. The original video, photo, and music files are linked to the project and aren't changed when editing in Movie Maker
• Can be opened and edited in Movie Maker from where it was last saved
• You can only open and view projects in Windows Live Movie Maker

Digital- A method of storing, processing and transmitting information through the use of distinct electronic or optical pulses that represent the binary digits 0 and 1.

Advantages and Disadvantages of digital data

Advantages

• The system does not have noise (random unwanted variation)
• Digital data doesn't degrade
• Less expensive
• More reliable
• Easy to manipulate
• Flexible
• Compatible with other digital systems

Disadvantages

• Sampling error
• Require greater bandwith than analogue to transmit the same information
• The detection of digital signals requires the communications system to be sycnhronised

Surveys and Interviews

Survey: a series of predetermined questions given to users of or participants in a system.

Purpose/ Advantage:

• When responses are multiple choice or ranked numerically on strength of feeling the results can be collated in a database or spreadsheet and the trends observed.
• Open questions provide an opportunity for users to respond freely and can reveal unanticipated needs.

Anonymous/Identifiable:

• Responders to a survey can be anonymous; anonymity could generate honest responses or conversely, dishonest or non-serious responses

Closed questions: a question with a suggested limited number of responses which should be selected by the responder

Advantages:

• trends can be can observed
• anonymity
• 
  

Disadvantages:

• does little to encourage the responder to open up
• not many people volunteer to complete surveys, often some sort of incentives are given to encourage responders

Open question: questions that do not suggest an answer and requires the responder to provide the answer

Advantages:

• answers are of the responder's personal opinion and is not limited

Disadvantages:

• trends cannot be easily observed
• accurate analysis cannot easily be made to find a relation between numerous surveys

Interview: discuss formally with (somebody) for the purpose of evaluation

Purpose/Advantage:

• open questions are normally employed, therefore they can probe more deeply than a survey
• may suggest surprising new directions

Focus groups: a group activity where you gather users or participants with similar interests in the system; brings together a no. of people for a group discussion or interview were all can contribute their ideas.

Understanding the problem

Closed questions: have a fixed number of answers
Ex. Which of the following is your favourite colour?

Open questions: does not require a tick box or anything of the sort.
Ex. 'What did you do today?'

Interview: more in depth, unexpected resp0nses,

Survey: time-efficient, requires enticement, can it be analysed?
A good survey has a combination of closed and open questions, mostly closed perhaps ONE open question where you can invite an uninvited response

Survey: URL, McAuley students fill
McAuley network information system is accessed using a computer or laptop
In the near future, students will be able to carry these laptops around with them

Q. Issuing laptops to students
(be unbiased; give staff the survey; hand survey out to different focus groups; make a list for focus group to choose eg. 1. Parents 2.Staff 3.Students)

Q. Bringing your own laptop
Stakeholders: students, staff, parents

Issues: laptop being stolen, lost, virus
Rate this issue according to its importance

System Development Cycle

Problems and Plans p.244

System Development Cycle (UMDIT)

1. Understand the problem- Interview participants, survery participants, what are the inputs? what are the outputs? what are the processes? who is involved with the system?
2. Making a decision- what type of solution? an IT solution? online or web-based?
3. Designing a solution- (making it happen), decide what software and hardware are required e.g. make a spreadsheet and put it up on sharepoint for a bus duty roster
4. Implementing the solution- preliminary testing. putting it on sharepoint, e-mailing everyone a set of instructions, installing hardware and software, training
5. Testing & Evaluating-Maintaining a solution- experiment (get someone to try it out), getting feedback, sample data (data that represents the day-to-day; typical data) and test data (checking for pan unusual or unexpected value)

Using Excel

• Formula; b7+c7+d7
• Function; =SUM (b7:d7)

Text book work- Systems Analyst & Ergonomics

p.309

A systems analyst researches problems, plans solutions, recommends software and systems, and coordinates development to meet business or other requirement. They work out what the needs of the users are and convey these needs to the designer of a system. (System analysts are the liaisons between vendors and IT professionals)

1. Name six ethical issues a systems analyst should consider.

• giving an honest evaluation of user needs to IT professionals
• ensuring that private information is not disclosed to unauthorised people
• ensuring equity in the workplace
• accuracy of analysis
• awareness of the impact the information system may have on the participants
• considering security of company information

2. Name four social issues a systems analyst must consider.

• deciding whether the information system should be machine-centred or people-centred
• ensuring an ergonomic work environment
• considering the psychological factors of the information system,
• ensuring the new information system makes participants' work more efficient

3. State the characteristics of people-centred systems.

• focus is on the problem, not the tool
• are easily understood
• provide templates and assistants
• work reliably
• are user-friendly and intuitive
• are placed in a suitable environment
• are safe
• are ergonomically sound
• take advantage of the users' skills
• look appealing
• are efficient
• reliever users of repetitive and boring tasks
• enhance relationships and interaction with fellow workers
• provide equitable access for all

eg. mobile phone, ATM machine, Google search engine, Laptops , Windows 7

4. In what ways are people like machines and in what ways are they different?

Similarities

• are required to get work done
• can understand the big picture as well as the detail
• handle data

Differences

• machines never get tired
• machines do not forget
• machines required programmed instructions to operate consistently
• machines not do act intuitively
• machines are incapable to think about the nature of work
• machines do not create new any new ideas or associations
• machines do not require training and retraining (need programming once only)
• machines cannot recognise nonsensical output

5. List the major advances in the desktop computer since the earliest models.

• Less bulky
• Require less space
• Flat VUDs
• comfortable keyboard
• aesthetically pleasing
• compact, wireless mouse and keyboards are available
• from CRT 15" monitors - LCD 22" monitors
• Use of DVDs, CDs and USB instead of floppy disks
• USB ports in front of PC, and not behind
• Use of broadband instead of dial-up connections
• Speeds have increased exponentially since then
• RAM on a machine today is 4GB (4 000 000 KB) in contrast to 32 KB or 1MB
  RAM- everything that a computer is working on at one time
• Multiple programs can run simultaneously (multitasking)

6. What do you predict the home computer system will be like in a decade's time?

- touch screen
-retina scan log-in
-voice operated

7. Identify the major social impacts that IT has had on our society in the past 20 years.

• machines have replaced people in workplaces
• machines make people's work less tedious and more efficient
• with the introduction of IT, there is also the issue of ergonomics and health and safety
• convenient
• communication between children (Digital natives)
• ways of storing photos, files has changed

8. Research details on RSI, both carpal tunnel syndrome and tenosynovitis (management on its causes, treatment and system design features that would reduce its impact on operators)

Repetitive strain injury (RSI) is an injury of the musculoskeletal and nervous systems that may be caused by repetitive tasks, forceful exertions, vibrations, mechanical compression (pressing against hard surfaces), or sustained or awkward positions. Treatment: ergonomics, break timers, keyboard alternatives and exercise.

Carpal tunnel syndrome is a painful disorder of the hand caused by pressure on the main nerve that runs through the wrist. Symptoms include numbness, pins and needles, and pain (particularly at night). Anything that causes swelling inside the wrist can cause carpal tunnel syndrome, including repetitive hand movements, pregnancy and arthritis. Treatment options include rest, splinting, cortisone injections and surgery.

Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon. Symptoms of tenosynovitis include pain, swelling and difficulty moving the particular joint where the inflammation occurs. Causes of tenosynovitis are unknown. Repeated use of hand tools can precede the condition, as well as arthritis or injury. Tenosynovitis sometimes runs in families and is generally seen more often in males than in females. Treatments for tenosynovitis depend on the severity of the inflammation and location. Mild tenosynovitis causing small scale swelling can be treated with non-steroidal anti-inflammatory drugs (NSAID) such as diclofenac (marketed as Voltaren and other trade names), taken to reduce inflammation and as an analgesic.

Treatments for tenosynovitis depend on the severity of the inflammation and location. Mild tenosynovitis causing small scale swelling can be treated with non-steroidal anti-inflammatory drugs (NSAID) such as diclofenac (marketed as Voltaren and other trade names), taken to reduce inflammation and as an analgesic.