Computer Systems and Databases Flashcards
Describe:
Control Unit
Manages the Fetch-Decode-Execute Cycle
Describe:
Arithmetic Logic Unit
Performs all arithmetic and logic calculations
Stores immediate results in registers
Describe:
Cache
Very fast memory in the CPU
Slower than registers but faster than RAM
Stores regularly used data so that the CPU can access it quickly
Low Capacity
Expensive
Describe:
Clock
Sends out electrical impulses that synchronise CPU components
Each clock signal allows one instruction to be executed
Describe:
Buses
Collections of wires that are used to transmit data between components of the CPU
Describe:
Registers
Temporarily hold small bits of data used by the CPU. Very quick
Describe:
Fetch Stage
Control Unit reads the memory address of the next instruction
Instruction is copied to a register
Decode Stage
Instruction is Decoded by the Control Unit
Control Unit prepares for next step
Execute Stage
The instruction is performed
Describe Optical Storage
Data is stored as pits on the surface
Surface is reflective
Laser beam shines on the surface and detects changes in position of reflected beam
Operating System Jobs
Memory Management
Security Management
CPU Management
Storage Management
Input/Output Management
Hardware/Software Management
Compiler
Translates source code all at once into one executable file
Interpreter
Translates and runs source code one instruction at a time, but doesn’t create an executable file
Databases
Primary Key - Identifier for individual table
Foreign Key - Uses Primary Key of other table to reference it
Field - Columns
Record - Rows
SQL Keywords
SELECT
FROM
WHERE
ORDER BY
INSERT INTO
UPDATE
DELETE FROM
* - Will return all fields
VALUES
