Random Access Memory (RAM)

Static RAM Cell

• cross-coupled inverters
• switches (transistors) used to control read and write of cell
• word line, bit line

RAM Array

Bits are stored as "words". Word sizes:

• 8-bits  - byte
• 4-bits - nibble
• 16-bits - 2 bytes or a double-byte

• rows of words
• address for each row
• each row can be read or written

• address lines
• data input lines
• data output lines
• read and write control lines
• RAM size

Review definitions: 1K 1M 1G

RAM expansion

Dynamic RAM - simpler cells, higher storage densities, cheaper, slower

Parity and Error-detection codes