Properties of memory cells:1.Exhibits two stable states (binary 1 and 0)2.Capable of being written into –to set the state3.Capable of being read to sense the state

DRAM SRAM•Dynamic•Memory cell is simpler•Requires data to be refreshed periodically in order to retain the data

•Static•No need to be refreshed since transistors inside hold the data as long as the power supply is not cut off.

1. SRAM is static while DRAM is dynamic2. SRAM is faster compared to DRAM3. SRAM consumes less power than DRAM4. SRAM uses more transistors per bit of memory compared to DRAM5. SRAM is more expensive than DRAM6. Cheaper DRAM is used in main memory while SRAM is commonly used in cache memory

Error correction is the detection of errors

and reconstruction of the original, error-free

data.

•No communication channel or storage device is completely error-free•As the number of bits per area or the transmission rate increases, more errors occur.•Impossible to detect or correct 100% of the errors•There are several Error Detection/Correction Methods

1. One of the most effective codes for error-recovery

1. Used in situations where random errors are likely to occur

- Single parity bit can only detect error, not correct it

- Error-correcting codes require more than a single parity bit

- Hamming codes work well when we can reasonably expect errors to be rare events. (ex: hard drives)

- Hamming codes are useless when multiple adjacent errors are likely to occur.