Computer Systems

Computer Systems Topic 12: Systems Specification and Selection

Scope and Coverage - 1 This topic will cover: Selection criteria System integration Accessibility Alternative solutions Identification, selection & justification Matching client requirements and system requirements with system components

Scope and Coverage - 2 This topic will cover (cont.): Systems options Off the shelf, self build, customise Alternatives System documentation Case study – selection & specification

Learning Outcomes By the end of this topic, students will be able to: Produce a system design specification to meet a client’s needs Evaluate the suitability of a system design specification Build and configure a computer system to meet a design specification

The Selection Process - 1 • Having determined the requirements, we need to select appropriate solutions. This involves: • Assessing whether computer and human resources are lacking • Do we actually need a new system? • Can we use existing technologies or is a fresh start better? • Is reuse of legacy systems a requirement?

The Selection Process - 2 • Do we have all the information we need about the requirements? • Is the problem a business model or a technology issue? • Is the information up-to-date? • Or will requirements be outdated by the time design decisions are made? • Are key stakeholders available during the whole project?

The Selection Process - 3 • What are the service levels required? • Are service level agreements (SLA) in place? • Estimate the costs and resources required • These need to be agreed with management or customer. • Identify any functions, processes and features currently lacking, as well as any new capabilities required by the new system. • Note that this may be an iterative process • It may be necessary to revisit some points as others change.

Selection Strategy • There are a number of different approaches to making systems selection, depending on the nature and size of the project. • Selection committee • Should include appropriate stakeholders and technical experts • Can be unwieldy and slow • Individual or small group decision • Often quicker than a full committee • May have biased views or not consider important aspects such as cost

Selection Considerations - 1 • When selecting a solution, you need to consider: • Needs assessment as discussed earlier • Volume of information to be processed • Customising solutions • Off the shelf products may not be suitable • The design must fully justify each component in the specification • Developing hardware and software specifications • Detailed specification of the necessary hardware and software

Selection Considerations - 2 • Request for proposals (RFP) • Invitation for tender in cases where different vendors may be required to provide specific components • May be used as a proposal for different computer system specifications • Evaluate proposals • Identify criteria for assessment of solutions based on priorities from requirements analysis stage.

Selection Considerations - 3 • Selecting additional services • Supporting services, after sales support • Ranking • A table may be used to establish a ranking of the possible solutions • Reporting • A concise document that fully justifies the selection made is a good evaluation tool

Selection Considerations - 4 • Negotiations • It may be possible or even necessary to reconsider and negotiate certain aspects of the system to get a better fit with the requirements. • Implementation • Issues may arise during implementation that impact the solution. • Review • To resolve any outstanding issues • To inform future projects

Selection Criteria - 1 • It is important to match the system specification with the requirements. • Acceptable response time • CPU spec, quantity of RAM, hard disk spec, network speed, printer speed • Availability (uptime, reliability) • Some systems are required 24/7/365, whereas others may only be used during office hours. • Some systems are mission critical and must be available when needed, whereas other jobs may be postponed.

Selection Criteria - 2 • Data capacity • Storage space, network throughput or bandwidth • Scalability • Will the demands on this system grow and can it cope? • Software • Is specific software required and if so, what are its hardware requirements? • Note that several of these performance requirements may be relevant.

Selection Criteria Classification • You can classify these selection criteria under three headings: • Time • Cost • Quality • There may be trade-offs between these criteria. • You can save time (i.e. do things quicker) but it costs more to buy faster equipment.

Application Software Choice - 1 • In most cases, you should specify the software first as software may dictate the hardware selection. • Software directly affects user perception. • Aim to improve user experience. • Speed or response time • Ease of use • Improved interface • Additional functionality • Manuals, user guides and training

Application Software Choice - 2 • In many cases, there is little choice • Compatibility with previous or legacy systems • Market dominance • Product availability

Operating System Choice • Often, there is no choice. Particular software may only run on a given operating system. The current options include: • Microsoft Windows • Apple Mac OS X • Linux • Android for mobile devices

Hardware Guidance - 1 • Often dictated by software requirements • Do not rely on “minimum hardware requirements” from software manufacturers • They really are an absolute minimum to get the software running. • They will seriously affect the performance of the system.

Hardware Guidance - 2 • Some uniformity is helpful. • Select the same base machine, or at least the same manufacturer • Upgrade where necessary with extra memory, faster graphics card or bigger hard disk. • This may result in a better negotiated price for the hardware. • Gives some redundancy across the entire hardware platform • Saves spares costs

Hardware Specification - 1 • Hardware selection should be driven by software choice and operating system choice. • When specifying hardware, you need to cover: • Computer architecture • This is the overall technology you are buying into • E.g. Intel/Windows or Apple Mac • Processor • Once the architecture is decided, which actual CPUs are you going to buy? • Intel in particular have a wide range of compatible processors with different performance characteristics.

Hardware Specification - 2 • Memory • How much RAM do you need for your software to perform properly? • Secondary storage • How much hard disk space is required? • What performance is required? • Some disks are designed for high transfer rates for use in video editing for example

Hardware Specification - 3 • Graphics capability • Most motherboards (and some CPUs) have some graphics capability built in. • On board graphics systems are often slow and may be limited resolution. • Do you need a high speed or high resolution graphics system? • Do you need multiple screens? • Connectivity • What do you need to connect to this system? • USB, Firewire, Ethernet, Wi-Fi, Bluetooth?

System Integration • System integration means making sure that all your systems work together. • Including all the new components, both hardware and software • Includes any legacy systems still in use • Includes any other equipment that needs to connect to these systems • E.g. point of sale or telephone equipment • Includes any data being transferred from old to new systems • Includes any manual parts of the business system

Accessibility • When putting in new computer systems, you should consider whether they are suitable for people with disabilities. This is a legal requirement in some countries. • Visual impairment • Larger screens, ability to change colours and fonts, text to speech facilities • Mobility issues • Different keyboard designs, voice input

Alternative Solutions • In most cases, you should specify alternative solutions, make recommendations and justify them. • Offer a minimum specification and a higher specification alternative. • Presumably at higher cost • Explain what extra benefits the higher spec will bring • If there are none, why are you suggesting it?

Alternative Approaches - 1 • When specifying new PCs, it is possible to buy off the shelf systems or build your own. • Buying off the shelf • May be cheaper • Will save time if you are putting in a large number of PCs • Will give better manufacturer support and guarantees

Alternative Approaches - 2 • Building your own PCs • Allows you to get exactly the components you want • Is better for a small number of systems • Is better for specialist requirements • Some manufacturers have base models that you can then customise when you order.

Matching Requirements • Your specification should be directly matched to the requirements. • In your specification report, explicitly match the specified components to the requirements. • Where alternatives are suggested, make it clear how each alternative satisfies the requirements. • Make it clear how your recommendations are a better fit for the requirements.

System Documentation - 1 • It is important to document the new system. • You may not remember everything. • You may not be there to answer questions in the future. • Other people may have to maintain or add to the system.

System Documentation - 2 • Include all the requirements analysis documentation as well as the systems specifications. • Include all the documentation that came with the hardware and software. • Keep documentation up-to-date when changes or upgrades are done.

Sources • You will need to search manufacturers and suppliers websites for technical information on the systems or components you are specifying. There are some global companies, but you can also search for local suppliers in your area. • www.intel.com • www.dell.com • www.apple.com • www.microsoft.com • www.hp.com

Topic 12 – Systems Specification and Selection Any Questions?

Computer Systems