Thư viện tài liệu, ebook tham khảo dành cho học sinh, sinh viên

The project scope defines the concept and range of the proposed solution. The limitations itemize certain capabilities that the product will not include. The scope and limitations help to establish realistic stakeholder expectations

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Describe user goals or tasks that the users must be able to perform with the system. Valuable ways to represent user requirements include use cases, scenario descriptions, and event-response tables. An example of a use case: "Make a Reservation" using an airline, a rental car, or a hotel Web site

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Phase 3: Design the system Notice that you don’t design the new system until you have done phase 2 since that establishes the requirements it must meet! Do a preliminary design Often involves prototyping Do a detail design, showing: Input requirements Output requirements Storage requirements Processing requirements System controls Backup...

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Procedural errors When people fail to follow safe procedures, errors can occur Software errors Programmers make coding errors Famous example: Utility billing software: Customer pays early – software credits account Customer pays late – software credits account, adds late fee in for next bill Programmer forgot to consider customers who pay ex...

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Data files are files that contain data such as words, numbers, pictures, or sounds These are the files that are used in databases They have extensions such as .txt .mdb, and .xls Graphics files have extensions like .tiff, .jpeg, and .png Audio files have extensions such as .mp3, .wav, and .mid Animation/video files have extensions such as .qt,...

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Satellite radio Digital radio signals are sent from satellites in orbit around the earth to subscribers that have special radios CD-quality sound is better than normal radio More channels than regular radio SDARS providers are XM satellite radio Sirius satellite radio Commercial-free

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Protocols The set of conventions governing the exchange of data between hardware and/or software components in a communications network Built into the hardware or software you are using Govern the packet design and transmission standards Examples are: TCP/IP for LANs and internet AppleTalk for older Mac networks SIP for Voice over IP (VoIP) ...

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Error Checking: Parity Bits Used in modems & communications to verify correctness One check bit is added to 7 bit byte The check bit is defined as either odd or even For odd parity, if the data sent is correct, the parity bit plus the first 7 data bits is an odd number For even parity, if the data sent is correct, the parity bit plus the first...

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Central Processing Unit (CPU) Management (continued) Queues, Buffers, Spooling Queue: First-in, First-out (FIFO) sequence of data or programs that waits in line for its turn to be processed Buffer: The place where the data or programs sit while they are waiting To Spool: The act of placing a print job into a buffer Needed because the CPU is fa...

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Modems High-speed phone lines ISDN line DSL line Cable Modems Satellite Always-on connection using satellite dish to satellite orbiting earth Send data at 56 – 500 Kbps; receive at 1.5 Mbps Wi-Fi & 3G

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