SJSU Systems Programming Paper

Overview

1. This problem concerns wind measurements made by the wireless weather station illustrated in Example 1-1. The wind-speed measurement uses a rotating anemometer connected by a shaft to an enclosed disk that is one-half clear and one-half black. There is a light above and a photodiode below the disk in the enclosure. The photodiode produces a 3 V signal when exposed to light and a 0 V signal when not exposed to light. (a) Sketch the relative appearance of voltage waveforms produced by this sensor (1) when the wind is calm, (2) when the wind is 10 mph, and (3) when the wind is 100 mph. (b) Explain verbally what information the microcomputer must have available and the tasks it must perform to convert the voltage waveforms produced into a binary number representing wind speed in miles per hour.
2. Using the scheme in Example 1-1, find the discrete, quantized value of voltage and the binary code for each of the following Fahrenheit temperatures: -34, +31, +77, and +108.
3. What is the exact number of bits in a memory that contains (a) 128K bits; (b) 32M bits; (c) 8G bits?
4. What is the decimal equivalent of the largest binary integer that can be obtained with (a) 11 bits and (b) 25 bits?
5. Write your full name in ASCII, using an 8-bit code: (a) with the leftmost bit always 0 and (b) with the leftmost bit selected to produce even parity. Include a space between names and a period after the middle initial.
6. Decode the following ASCII code: 1000111 1101111 0100000 1000011 1100001 1110010 1100100 1101001 1101110 110001 1101100 1110011 0100001.