hardware devices

Question 1

dynamic RAM (DRAM)

Answer 1

• constructed from capacitors which need regular recharging
• uses a single capacitor per bit
• stores each bit as a charge

Question 2

static RAM (SRAM)

Answer 2

• constructed from flip-flops which continue to store data indefinitely while computer is switched on
• doesn’t require refresh
• uses more than one transistor per bit → more complex circuitry

Question 3

solid state drives (SSDs)

Answer 3

• NAND-based flash memory with no moving parts
• uses grids and columns of rows with two transistors at each intersection, one called a floating gate and the second called a control gate
• memory cells store voltages, representing a 0 or a 1
• movement of electrons controlled to read/write

Question 4

CD-ROM

Answer 4

disc spins and laser beams are reflected from dis surface. reflective surface has indentations called pits separated by lands. when disc is read, travel of laser beam to pit causes a difference in phase compared to reflection from a land. this is recognised by a photodiode detector and attached circuitry and interpreted as a 0 or 1. single spiral path

Question 5

DVD-RW