1. An analog to digital converter (A-D converter) transfers data to a computer.
After conversion the binary value is 0100111.
(a) State the equivalent decimal integer value.
(b) State one application that requires an A-D converter.
(c) Outline the need for an A-D converter.
2. A petrol station has 10 pumps and there are four grades of fuel available
at each. The system is completely self-service. Each pump is fitted with a microprocessor.
When the customer starts to take fuel by picking up the petrol dispenser the
microprocessor records the amount of petrol taken and the cost whilst petrol
is being dispensed.When the customer replaces the petrol dispenser, the data
of the transaction is relayed to a computer held in the office. When payment
is made a message is sent back to the pump to clear details on the amount taken
ready for the next customer.
(a) Explain why an analogue digital converter is needed at the pump.
(b) Determine what would need to be held in the ROM of the microprocessor at
each pump.
3. (a) Describe one application of sensors.
(b) Explain why the signal from a sensor requires conversion before processing
in a computer.
4. The World Organization for Weather Information (WOWI) collects data about temperature, air pressure, wind direction, and various other measurements. These measurements are recorded each hour in 100 cities around the world. WOWI also saves satellite photos. All data and photographs are stored in a central computer in London, England. WOWI makes the data available, free of charge, to anyone who wants it. Typical users of the data are radio and television stations, for daily weather reports. Identify part of this system which requires analog to digital data conversion.
5. A multimedia software utility retrieves data from a hard-disk at a speed
of 5 MB per second.
(a) Calculate the data-transfer rate in kb per second.
(b) State whether digital-to-analog conversion is performed by multimedia software,
a hardware device, or the operating system.