Chap 1 Computers and Information EE2030 Dr John A Copeland Logic and Computer Design Fundamentals 2nd Edition M Morris Mano Charles R Kime http www ece gatech edu academic courses ece2030 http www csc gatech edu copeland 2030 1 Signals Physical Types Voltage Current Photons Fixed Number of Discrete Levels digital not analog 2 levels binary simpler circuits for computers Called true false high low or 0 1 multi level good for communications EE4604 2 1 volt noise margin 1 volt noise margin 3 A binary number is called a Bit Eight bits as a unit are called a Byte Bits may reside on different memory elements in a semiconductor memory chip C charged or not on different spots on a magnetic disk M or on different spots on a CD pit or no pit on the input and outputs of logic gates in a computer register or on a bus 4 Floppy disk hard drive RAM semiconductor IC CD ROM Data and program instructions FPU MMU Internal Cache Keyboard mouse CRT or LCD Display 5 If base 10 new symbols must be defined for 11 12 1x8 3 13 base10 1x8 0x4 1x3 1 11 base10 6 Used in pocket calculators reduces binary to decimal conversions 7 Alphanumeric characters assigned a 7 bit pattern or binary number B7B6B5B4B3B2B1 e g A 1000001 Normally Bytes are expressed as B7B6B5B4B3B2B1B0 The bits shown above would be 6 0 and B7 is the parity or high order bit 8 Codes 0000000 0 to 0011111 31 Tab I LF J CR M End of Line Teletype and DOS LF CR UNIX LF Macintosh CR LF Line Feed CR Carriage Return 9
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