3.2.7 Outline the function of a microprocessor designed to perform one or
a limited number of functions (within a car, washing machine and so
on).
Teaching Note:
The need for different types of memory in a microprocessor must be
understood. Students must be able to quote at least one example of
the use of a microprocessor and state the inputs and outputs.
Sample Question: And an important quintessential example of an SL question which doesn't really relate to specifics in the syllabus, but which, when thought about is not that hard to answer. With these sorts of SL questions, just use your common sense if what is being asked is not from any assessment statement you can recall.
A DVD recorder, which is controlled by a microprocessor, can be programmed to
record TV programs via a simple interface controlled by a handheld remote control.
(a) State the name of the DVD’s computerised component that controls the DVD recording function. [1 mark]
(b) Identify two key inputs to this component in relation to the recording function. [2 marks]
(c) Describe how these inputs would be stored and retrieved. [2 marks]
(d) Explain how the component would control the recording. [3 marks]
JSR Notes:
Maybe the biggest thing here is to appreciate what this assessment statement is referring to. The CPU is, in fact, a “microprocessor”; it’s just that it’s an incredibly sophisticated one. The microprocessors in question here are the relatively small and simple ones found in every-day electronic devices, like your digital watch, your refrigerator at home, and so on.
So, there’s not a lot here in the textbook for this one. So let’s focus on what the assessment statement is geared toward. First, let’s start with the teaching note above. The focus is on the kind of memory used in microprocessors. The idea here is that it doesn’t need a lot of volatile memory that changes significantly each time the program is run, since it’s doing a limited number of small jobs the same way, again, and again. So, yes, it will have a few registers that take in the given input “of the day”, but generally the memory is of the ROM variety.
Then, you need to be able to come up with one example of a microprocessor in an every-day device, and be able to list the inputs and outputs that it deals with. And since a car and a washing machine are indeed mentioned in the syllabus, why not use them. Take a look on page 150 of the textbook, and make sure that not only do you know what the various microprocessors do, but that you are able to state the inputs and outputs.
I won’t spoil you too much, but here’s an example of a couple of every-day microprocessors found in the computer lab, with, importantly their function, and their inputs and outputs..
Air Conditioning Temperature Control Unit:
Function: Regularly takes a temperature reading, and if the temperature is greater than the temperature selected by the user, then either or both of fan and refrigeration unit are cranked up.
Inputs: A sensor inputs temperature readings
Output: Fan speed, and power level of cooling
Toner Cartridge Level Indicator
Function: To monitor the amount of toner left in the toner cartridge, and send a warning of low level to the LCD display of the printer.
Input: Sensor senses the percentage of toner left in the cartridge.
Output: A digital indication of the percentage of toner left, upon request, and/or a warning signal to the printer LCD when the toner is below a certain percentage.