Chapter 1 - Chapter 1 computer a device that accepts input...

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Chapter 1 computer: a device that accepts input, processes data, stores data, and produces output. Draw a picture of computer input central processor output device main memory 16 Megabytes secondary memory fixed disk 1 Gigabyte floppy disk 1.4 Megabyte accepts input: words and symbols in a document, numbers for a calculation, pictorial input, audion signals from a microphone, mouse clicks from a mouse, instructions for a process: input devices: keyboard, mouse, scanner, digitizer tablet, microphone (speech input), bar code scanner processing of raw data done by central processor (CPU): electronic circuitry in form of computer chips. Performs arithmetic operations (add, multiply, subtract, divide) at incredible speeds 109 operations per second. Also, performs comparisons of two numbers stored in memory (which is larger, which is smaller, are they equal). Based on these comparisons, CPU chooses from among alternatives and decides whether to continue a repetetive operation or to stop. Computer stores data in memory (main and secondary). kinds of data stored: any of the input data we mentioned earlier. Normally the instructions for a process are stored as well as the raw data to use in the processing. -- Stored program computer/Von Neumman computer. Each memory cell has unique address (fixed) but its contents can change (memory is volatile). Main memory directly accessible by the central processor - secondary memory is not. All data and instructions must be moved into main memory to be processed. Main memory is limited in size - up to 32 Megabytes for many computers. Seconday memory is not limited. Can be expanded almost indefinitely by removable storage media - disks, tapes, CD ROMs. Main memory is not permanent memory - contents disappears when computer is turned off. Secondary memory (storage in book) is semi- permanent - data stays on disk until you erase it. Bring a couple of disks to class - floppy disks 3.5 inches - IBM formatted - high density - 1.44 Megabytes ouptut devices - screen, printer, plotting device - draws graphs, maps, etc. To compute a water bill:
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step 0. Assume a program has been written and stored in computer memory as a list of instructions. The computer begins to execute the program instructions, which cause the following sequence of operations to occur: 1. Computer reads data (number of gallons used, category of user - industrial, home) entered at keyboard into memory. 2.
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Chapter 1 - Chapter 1 computer a device that accepts input...

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