Unit 1: Computer Hardware
Data
The values you work with.
Exactly: Represented values such as numbers, typed characters, or sound samples.
Mix-up alert: Data are not only numbers. You need context to interpret what values mean.
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Computer Science
33 key words. Find a meaning, clear up a mix-up and return to the lesson.
Look up an idea, then open its definition and lesson. Visited marks are for this visit only.
33 words · Choose a word to read its meaning.
The values you work with.
Exactly: Represented values such as numbers, typed characters, or sound samples.
Mix-up alert: Data are not only numbers. You need context to interpret what values mean.
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Follow a related word to see how the ideas fit together.
Data. 7 words link to it. It links to 1 word.
33 words shown.
A machine that follows instructions to work with data.
Exactly: A computer carries out programs. Its functions include input, processing, output, and storage.
Mix-up alert: A keyboard or screen alone is not what makes something a computer.
Instructions a computer can carry out.
Exactly: A set of instructions that tells a computer how to work with data.
A computer built inside another device.
Exactly: A computer built into another device to do a particular job, such as a programmed controller inside a microwave.
Mix-up alert: A computer does not have to look like a laptop or have a keyboard.
One computer that can run many different programs.
Exactly: A computer that can run different programs for different tasks, such as a Chromebook used for writing and for calculating.
Mix-up alert: An embedded computer is built into another device for a particular job.
Data or commands coming IN.
Exactly: The function that brings data or commands into a computer system, such as detecting a tap.
Mix-up alert: A touchscreen detecting a tap is input. The same screen showing a menu is output.
Doing the WORK with data.
Exactly: Applying instructions to data, such as calculating a total or comparing values.
Mix-up alert: Calculating a total is processing. Displaying it is output.
Sending a result OUT so someone can use it.
Exactly: The function that communicates a result, such as displaying text, playing sound, or printing a page.
Mix-up alert: Seeing output on a screen does not prove a file was saved.
KEEPING data or programs for later.
Exactly: The function of retaining data or programs for later use, such as keeping a saved file.
Mix-up alert: Showing a result is output. Keeping it for later is storage.
The values you work with.
Exactly: Represented values such as numbers, typed characters, or sound samples.
Mix-up alert: Data are not only numbers. You need context to interpret what values mean.
What the data mean in a situation.
Exactly: Meaning obtained by interpreting data in context, such as using labeled counts to work out how many chairs a club needs.
Mix-up alert: A neat table alone does not explain what unlabeled numbers stand for.
The physical equipment.
Exactly: The physical parts of a computer system, such as a keyboard, microphone, processor, or screen.
Mix-up alert: The screen is hardware. The app it displays is software.
The programs and instructions.
Exactly: Programs and instructions used by a computer system, such as a spreadsheet or drawing application.
Mix-up alert: A button drawn on screen is part of a software interface, not another physical button.
The details that tell you what data are about.
Exactly: Details about what data describe, such as what a number counts. You need context to interpret data correctly.
Mix-up alert: A neat table is not context by itself. Labels must say what each value means.
The part that carries out the instructions.
Exactly: The processor that executes program instructions, using working data held in RAM.
Mix-up alert: RAM holds current work. The CPU carries out instructions; RAM does not do the calculations for it.
Working space for what the computer is using now.
Exactly: Working memory holding data and instructions in use. Ordinary RAM loses its contents when power is off.
Mix-up alert: More RAM does not directly add space for saved files in persistent storage.
The place that keeps saved files when power is off.
Exactly: Storage that retains saved data and programs beyond the current powered session. Deletion or damage can still lose files.
Mix-up alert: Persistent means retained without power, not impossible to lose. Cloud storage uses persistent storage on computers elsewhere.
Loses its contents without power.
Exactly: Describes memory that does not retain its contents when power is removed, such as ordinary RAM.
Mix-up alert: This describes RAM, not a saved file in persistent storage.
Connected equipment that helps a computer do a job.
Exactly: Equipment connected to a computer for functions such as input, output, or storage. Examples include an external keyboard, printer, or storage drive.
Mix-up alert: A peripheral is not the CPU. Its connection may use a cable or be wireless.
A socket where you plug equipment in.
Exactly: A physical connection point that accepts a matching plug. Its stated capabilities help determine what connected equipment can do.
Mix-up alert: A plug fitting does not prove that every needed capability is supported.
Being able to work together for the job.
Exactly: The ability of equipment to work together for the stated task. In class, check it using the supplied capability information.
Mix-up alert: Do not infer compatibility from price, capacity, or a plug fitting alone.
A connection with no cable between the devices.
Exactly: A connection that carries data without a connecting cable, using radio signals such as Wi-Fi or Bluetooth.
Mix-up alert: Wireless equipment still needs power and a compatible connection.
How much it can hold.
Exactly: The amount of data that memory or storage can hold. Compare amounts in the same unit.
Mix-up alert: Capacity is not speed. More saved-file space does not prove faster calculations.
The list of facts about what a device can do.
Exactly: A description of a device's features and capabilities, used as evidence when checking requirements.
Mix-up alert: A bigger number on a spec does not prove a device is right. Check every requirement.
One 0 or 1. The SMALLEST piece of computer data.
Exactly: A binary digit: a single 0 or 1. It records the state of one switch, off or on.
Mix-up alert: A bit is not a byte. It takes 8 bits to make 1 byte.
A group of 8 bits.
Exactly: Eight bits handled together. One byte has 256 different patterns, enough for the numbers 0 to 255.
Mix-up alert: A byte is 8 bits, not the other way round. A bit is the smaller one.
A way of writing numbers with only TWO digits: 0 and 1.
Exactly: A number system where each place value is a power of two: 1, 2, 4, 8 and so on. Computers store all data in binary.
Mix-up alert: 1010 in binary is ten. It is not one thousand ten.
What a digit is worth because of WHERE it sits.
Exactly: In binary, the columns from right to left are worth 1, 2, 4, 8, 16, 32, 64 and 128. Each column is worth double the one to its right.
Mix-up alert: A 1 in the 8s place is worth 8. A 1 in the 1s place is worth only 1.
Change how a number is WRITTEN without changing how much it is.
Exactly: Binary to decimal: add the place values that have a 1. Decimal to binary: take the biggest place value that fits, write 1, subtract, and keep going.
Mix-up alert: Converting changes the writing, not the amount. 1011 in binary and 11 in decimal are the same amount.
An AGREED RULE that gives bit patterns a meaning.
Exactly: A set of rules for turning information into bits and back again. The reader must use the same encoding as the writer.
Mix-up alert: Bits do not carry their meaning inside them. The same pattern can mean different things under different encodings.
The bit pattern that STANDS FOR one thing under a rule.
Exactly: In an encoding, each letter, number or instruction gets its own pattern. In ASCII, the code for A is 01000001.
Mix-up alert: Here a code is not a secret message or a program. ASCII is public, so computers that use ASCII agree on these letter codes.
One letter, digit, space or symbol in text.
Exactly: A single unit of text, such as A, 7, a space or a question mark. ASCII gives each character a number code. In these activities, assume one byte per capital letter: A is 65, written 01000001.
Mix-up alert: A character is not always exactly one byte in real text. When a question says "assume one byte per character", that is a rule for that question.
One tiny square of color in a digital picture.
Exactly: The smallest dot in the grid that makes up a digital image. Each pixel's color is stored as one or more bits.
Mix-up alert: More bits per pixel means more possible colors, not more pixels. More stored bits do not guarantee a better-looking picture.
How much space data takes up, measured in bits, bytes, KB, MB or GB.
Exactly: 8 bits make 1 byte. In this course, 1 KB is 1,000 bytes, 1 MB is 1,000 KB and 1 GB is 1,000 MB. Some computers count 1,024 instead of 1,000. For picture calculations, count pixel data only: ignore headers, padding and compression. Divide the total bits by 8 and round up to whole bytes only if they do not divide evenly.
Mix-up alert: A bigger file is not always a better picture. Size depends on the number of pixels, the bits per pixel and the file format.