Introduction I have been given the task of creating a system for a hospital to keep records of their loan equipment. It needs to be able to keep records of what equipment has been borrowed, by whom and when, and also if any equipment is unavailable as it is in repair. Systems Life Cycle We have already been given the information for a problem definition, feasibility study and analysis, but have been told that we do not need to do these stages of design. However if I were to document the whole system I would use the system life cycle, as it helps designers approach the design in a methodical way.
I have shown the life cycle below: 1. Problem Definition – the problem will be defined by the user 2. Feasibility Study – investigate the system and decide if there is need for a new system 3. Analysis – analyse the requirements and produce a specification 4. Design – the design is produced 5. Construction 6. Testing – system is fully tested 7. Implementation – system implemented and users trained 8. Maintenance – there are three types of maintenance: a. Perfective maintenance, where you make the system easier to use or you add new facilities b.
Adaptive maintenance, where you make changes to suit the changes in working environment c. Corrective maintenance, where you change something because of errors discovered in the original system 9. Evaluation – evaluation of the system and if it meets the requirements of the user Gathering Data If I had to collect the data on the requirements of the new system and the problems with the old one, I would use the following four techniques: 1. Interviewing staff at different levels about the present system and what they would like to see from the new system.
2. Sending out questionnaires and analyzing results. 3. Observing current procedures with current system. 4. Examine current business and systems documents and outputs Problems of Existing System The present system in use at the hospital is a manual one, this means everything is recorded by hand on paper. This is an extremely inefficient way of recording the data as information can easily be lost or misplaced. We are also told that there is a need for a new system to “cut down on loss and wastage”, so the new system must be reliable.
This suggests that the secretary has a lot to do with the possibility of hundreds of different files. Objectives of New System There are several specifications for the new system, these are: 1. Ability to store details of equipment (how many in stock and price of equipment) 2. An Item code has to be devised which identifies each piece of equipment individually, while also indicating what type of equipment it is. 3. Be able to find information for any individual piece of equipment:
a. Whether it is available, being repaired or out on loan b. If on loan, to whom, and at what address or ward numberc. If on loan, when it is due for return or the loan renewed d. If being repaired, when it was sent for repair 4. Be able to produce a hard copy of this information for any piece of equipment 5. To enable patients to have more than one piece of equipment out on loan at a particular time (e. g. 2 crutches and a wheelchair) 6. At the end of each week, a full report of the location of all equipment is to be produced. If equipment is due for return or renewal during the following week, that patient must be contacted, with a standard letter. DESIGN.
Feasibility of Using a Computer Based System: It has been required that I should produce a computer based system for the hospital. There are many advantages to a computer based rather than a non-computerised system these advantages include: * Computer systems can be backed up on a regular basis very easily. So that in the event of a fire or if the computers were to contract a virus, the files are not lost altogether. However if the system was not computerised and there was a fire, the data would be lost. This could lead to a loss of customers due to a lack to reliability.
A computer system can be modified and changed more easily than a non-computerised system. E. g. if you wanted to change the format of the customer data entry forms on a computer it could be done in a few minutes but manually on a non computerised system it would take a very long time to rewrite the records if they were held on card. * A computerised system can find files within seconds where as on a card filing system it would take people a lot longer as it has to all be done by people and then the process is subject to human error. Performance Requirements:
The client has stated that one of the main reasons to have the system is to save time and cut down on wages. This means that the system must be capable of retrieving data quickly and the system must be easy to use. The speed is one of the major factors, but must create a system that does not take up vast amounts of memory. Costs: The initial starting out costs will be the machine purchase, and basic unit for it to go on (unless already owned). Other costs that must be taken into consideration are training costs, staff will have to be trained how to use the system quickly and efficiently.
Staff training costs should be low as the system is going to be designed so that it is easy to use and understand, this helps both the employee pick it up quickly and the employer spending less money on staff training. Maintenance is not going to be a major cost, the system will be designed to work effectively around the clock so will not need extra time and money spent on it. I will now look at the hardware and software which are most appropriate for the system: Hardware The hardware of a machine is the physical machinery, which makes up the computer.
In order to start to think about designing a system I need to first of all think about the possible use of different types of hardware: – Computer – The actual machine which processes all the data Keyboard – used mainly to enter in data about the customer, equipment and loan duration Visual Display Unit – A user-friendly way to display the system. Computer mouse – to select different function options. Screen Touch Screen – to speed up the input of data and other functions within the system. Screen pens – to speed up processes within the system especially the input of data.
I have decided to keep the hardware simple any only have a computer, keyboard, VDU and mouse. This is relatively cheep compared with the other options and will be easy for the user to understand. Software There are three main choices of software these are Excel a spreadsheet, Access a database or a high level language such as Pascal. All have advantages and disadvantages. Excel: Excel has many advantages including:
Excel allows you to insert buttons or macros these allow you to open and close forms at the click of a button.They also allow you to do things like calculations and formulas. Excel allows you to highlight different cells in colour and fill effects. There is a formula bar at the top, which displays the formula of the cell you are viewing; here you can also edit the formula. You can create look-up tables. You can create graphs using the easy to understand Wizard tool. In Excel you can also copy the cell of a formula from cell you cell. This can be very useful when using a formula to calculate a certain equation. You can name cells, giving one a unique cell reference.
Excel is a multi dimensional spreadsheet, this means that you can have as many sheets as you want, this is also known as a three dimensional spreadsheet. I have a relatively good knowledge of this software Excel has disadvantages as well as advantages, these include: – If you change the name of a page after making a macro it can’t find the correct page because it has changed names. This means you then have to go into Visual Basic and manually change the name of the page on the actual piece of code. This all takes time and if you change more than one page’s name it will take a very long time.
With the labels of the graph they will not change with the data so you end up having to go over the whole process of making a graph again. Access: I will now look at the advantages and disadvantages of access: Access can make forms to insert data. In Access you can have macros to go between forms and queries. Access is not a flat file database so you can also create relationships between tables of data. It has a query language, which means it can perform advanced searches. You can hide certain forms out of view. You can put a password on the system to prevent people tampering with it.
There are writing tools including spelling and punctuation tools available. Access can have relational tables, which are linked together. This avoids repetition in entering in data as more than one department of the system can share one bit of data. Access has disadvantages as well as advantages these include: – Access is more sophisticated than Excel and is therefore harder to use for a novice. Access is used by professional system designers who design systems for end users. This means the system must be very powerful and very detailed. However it is more complicated for a non-expert to use.
I have little knowledge of this particular software High Level Languages: Advantages: Can be created to suit the customers need exactly I have a fairly good knowledge of this software Disadvantages Takes a lot longer to code a program rather than using tables in Excel or Access I am not an expert at using high level languages so I will be prone to errors that perhaps would not happen with a package such as Excel or Access. Evaluation of Software: I have decided to choose Excel to use as I have a greater knowledge of this software and I think that the final product will be easier for the end user.
Although Access offers a lot more features and functions I am not familiar with them so creating the system would take much longer. Excel is a quick piece of software which can open files very fast, although Access is faster than Excel I think that the difference in speed is hardly noticeable so it hasn’t affected my decision. Excel is easily upgradeable, enabling the hospital to introduce new functions and modify it without any hassle. I decided not to use a high level language such as Pascal, as although I have a good knowledge of it, the time requirements do not enable me to create the system this way.
I would have liked to use this software as it can give the end user exactly what they want and I enjoy using and learning high level languages, but due to the time constraints it is not possible. Data Requirements: The data requirements for the system include the following: Data of all the equipment the hospital owns, including the cost of replacement and the unique item code for each piece of equipment. Data on where the equipment is, in which ward or at what address, which patient it is with, or if it is in repair and also when it is due back.
Data on the patients, this will include patient ID, patient title, patient forename, patient surname, patient street name and number, town, postcode and patient contact number. Data Flow Data Flow Diagrams: To help me with the design I have drawn a data flow diagram to show the logical movement of the data through a system, this is often used when creating systems as it helps to make the design as effective as possible. However it does not show how the data is stored. There are different levels of data flow diagrams, I have drawn a level 1 diagram that can also be known as a context diagram.
A data flow diagram has many symbols, which have different meanings, the symbols I have used are: – * External Entities – can also be known as a data source or destination. In the following diagram the Patient is the External Entity. * Processes – are operations performed on the data. In the following diagram the processes are each named P1, P2 … etc. * Data Stores – are logical stores for data, which are not physical in the following data, flow table they are labelled D1 and D2. There are many different levels of DFD’s (Data Flow Diagrams), the DFD below is a level 0 and the DFD on the following page is an example of a level 1 DFD.
Entity-Relationship diagrams Entity-relationship diagrams show the relationship between entities. Entities are things in which data is held. In order to be able to draw an entity-relationship diagram you need to know the degree and the name of the relationship. The degree of the relationship will come under one of three categories: 1. One-to-one, e. g. relationship between Person and National Insurance number which is unique to every person. 2. One -to-many, e. g. relationship between Tree and Leaf, the tree has many leaves but the leaves only have one tree.
3. Many-to-many, e. g.relationship between Books and Readers in a library, many books have many different readers and vice-versa. I have demonstrated the entity-relationship diagrams below with ones that are relevant to my system. The above many to many relationship can be broken down into: System Design Top Down Design: Top-Down design is a way of breaking down a problem into the major tasks to be performed, each of these then being further broken down into separate sub-tasks, and so on until each sub-task is simple enough to be written as a self-contained module or procedure. The program then consists of a series of calls to these modules.
This is mainly used in programming but it can be used to help me with my system. Jackson Structure Diagram: It is useful to have a way of representing this breaking down of modules and some way of showing how they all relate to each other. A Jackson diagram is a simple way of doing this. I have included a Jackson diagram below: User Interface: This describes the method in which users communicate with a computer. Good interface is important because:- 1. Safety Factors, e. g. If a pilot on an aeroplane can’t use the computer it crashes 2. Need For Efficiency, in terms of time and money. 3.
Enjoyment, Staff will not want to be stressed with an awkward system that they find difficult to use. A good user interface is an important part of a successful system, the design must take into consideration: Who is going to use the system – experienced users, members of the public or even children What Tasks the computer is performing – life threatening procedures such as controlling a life support machine or flying a plane, or just using databases and spreadsheets. The Environment in which the computer will be used – calm and quiet or busy and noisy What technology is feasible.
In particular, careful screen design is important as it can make a huge difference to the usability of a system. When designing my system I will take the following points into consideration: A title should be given to the display It should not be too cluttered, use spaces and blanks to make it look better It should indicate the size and format of data entry in each field Items should be in a logical order to make it as easy as possible for the end user Colour should be used carefully Default values should be entered wherever possible Adequate help facilities should be provided.