unit 1
　text 1: octal and hexadecimal numbers
　reading l: positional number systems
unit 2
　text 2: floating-point numbers
　reading2:ansi/ieee-754 format
unit 3
　text 3: diodes
　reading 3: power converters
unit 4
　text 4: digital waveforms
　reading 4: a digital waveform carries binary information
unit 5
　text 5: basic logic operations
　reading 5: the nyquist criterion: relating bandwidth to symbolrate..
unit 6
　text 6: review of four basic analog filter approximations
　reading 6: summary of memory byte pools
unit 7
　text 7: the growth of bandwidth and the digital revolution
　reading 7: the transmission of images
unit 8
　text 8: superposition
　reading 8: linear systems
unit 9
　text 9: low pass filters