Selecting Implementation Strategies When performing the top-level or architectural design of a system, engineers will partition the required functions between system resources. Some functions may be performed using a human operator; others may use mechanical arrangements while others will use electrical or electronic circuits. In many cases a computer system will provide some of the functionality and under these circumstances it is normal to partition the requirements between the hardware and the software. However, in many cases the use of data offers a third distinct implementation and functions may be partitioned. Partitioning of System Functions Required Functions –Data –Software –Hardware
What Is Electrostatic Discharge Electrostatic Discharge (ESD) is the term given to the discharge of static electricity. We have all experienced what is known as an 'ESD event', an unplanned discharge of static electricity, in our everyday lives. For example, if we have had a shock from a metal doorknob after walking across a carpet on a dry day, or climbing out of a car from the metal body of the vehicle. When our clothes cling to each other after removing them from the dryer, it is caused by an electrostatic charge. In its most dramatic form, the lightning in a thunderstorm is a huge electrostatic discharge.
continuation Static Electricity is defined as an electrical charge caused by an imbalance of electrons on the surface of a material. This imbalance causes an electric field that can be measured and that can influence other objects at a distance. Electrostatic Discharge (ESD) is defined as the transfer of electrostatic charge between bodies at different electrostatic potentials caused either by direct contact or by an induced electrostatic field.
What is EMI? Electrical machine interference –Motors –Welding machines –Ballast or transformer vibration –Loss-connected wires –Etc.
Definitions Voltage – the force which moves an electrical current against resistance Waveform – the shape of the signal (previous slide is a sine wave) derived from its amplitude and frequency over a fixed time (other waveform is the square wave) Amplitude – the maximum value of a signal, measured from its average state Frequency (pitch) – the number of cycles produced in a second – Hertz (Hz). Relate this to the speed of a processor eg 1.4GigaHertz or 1.4 billion cycles per second
Digital signals Represented by Square Wave All data represented by binary values Single B inary Dig it – Bit Transmission of contiguous group of bits is a bit stream Not all decimal values can be represented by binary
Analogue Signals Human Voice – best example Ear recognises sounds 20KHz or less AM Radio – 535KHz to 1605KHz FM Radio – 88MHz to 108MHz
Technician's tools Oscilloscope - frequency, voltage, current and wave pattern Multi-testers – components and voltage testing Logic probe testing gates Anti-static wrist pad Plastic screw drivers Assorted peripheral cards Assorted line cables and adaptor connectors Soldering iron (20-25 watts) Cutter pliers Long nose pliers Cutter blades Jumper wires Set screw drivers flat and Philips Cleaner fluid Sand paper IC clamp or remover
Computer Comfort and Ergonomics Low voltage consumption Low radiation and emission Brightness is within the requirement Positioning (keyboard and monitor) Regulated cooling system Regulated power supply Plug and play capability
Preventive Maintenance Use of correct voltage supply (UPS) Location of computer system Computer room environment Regular maintenance and repair Regular computer upgrade (hardware and software) Daily computer files repair and cleaning
Operating System – Basic Services Programs that accept commands and requests from a user and a user’s program Manages, loads, and executes programs Manages hardware resources of the computer Act as an interface between the user and the system
Operating System – Additional Services Provides interfaces for the user and the user’s programs File support services I/O support services Means of starting the computer –Bootstrapping or booting the computer –Initial Program Load (IPL) Handles all interrupt processing Network services Provides tools and services for concurrent processing
Risks and Safeguards The prolonged malfunction of a computer Can cause the loss of hardware, software, data, or information aging hardware natural disasters such as fires, floods, or storms random events such as electrical power problems What is a system failure?
Using a Multi-meter or Digital Meter Correctness and accuracy of measurements Settings range of the testers Comparative analysis of test results