Topic 2: Data

Components inside computers have billions of transistors. Binary is used to represent the transistors inside the component. Transistors can be on or off (1 or 0).

A structure in which the hardware is connected and organised. It consists of Main Memory and a Central Proecessing Unit interconected by buses. Main Memory (Read)!\_\_\_\_\_¡(Write) Input --> Central Proecessing Unit --> Output The CPU reads and writes data & program instructions to and from main memory.

When the result of a binary calculation requieres more bits than are available in the computer hardware (register)

Remove the - sign Convert the number to binary Flip the bits Add 1

Remove 1 Flip the bits Convert to denary Add a negative sign (if the original number started with a 1)

When doubling, shift/move all bits to the left When halving, shift/move all bits to the right

Binary digit

File size(bits) = width(px) x height(px) x colour depth(bits)

• Used to avoid errors when manipulating numbers • Represend binary numbers using smaller digits (1 hexadecimal digit = 1 nibble) • Computers don’t process hexadecimal

kilobit - 1000 bits megabit - 1000^2 bits gigabit - 1000^3 bits kilobyte - 8 x 1000 bits megabyte - 8 x 1000^2 bits gigabyte - 8 x 1000^3 kibibyte - 1024 bits mebibyte - 1024^2 bits gibibyte - 1024^3 bits

Reduce file sizes by repackging or removing some data

Reduce file size while retaining the exact meaning of the original data.

It reduces file size by permanently deleting some of its data.

Characters in texts

Using the ASCII table, each character has a unique bit pattern. Is a 7-bit code, there are 128 sequences/patterns.

With a microphone (or a recording device) a computer will take samples at a fixed interval (usually thousands of samples per second), it will then convert these values into binary to be stored in a file.

file size (bits) = sample rate(Hz) x bit depth(bits) x recording length (seconds)

An unsigned integer has no positive or negative sign, a signed one does. Signed: -8, +8 Unsigned: 8

“Sausage” - Start/Stop Rectangle - Process Rhombus - If/elif/else (conditionals) Parallelogram - Input / Output Rectangle with vertical borders - Subprograms

Repetition of code

Breaking down a big problem into smaller parts