What is the maximum capacity for DDR3/DDR4 RAM? What is the difference between SDR and DDR? Which of the triplets is SRAM? What is stored by primary storage components? What happened when the industry changed from SIMM to DIMM technology?

Secondary Storage Backups & Crashes

Intro Bits & Bytes Types Magnetic Optical Paper Read & Write Rapid degradation Optical Read…maybe write Slow degradation Paper

Bits & Bytes 1 Bit – 0 or 1 8-bits – 1 character – 1 Byte Kilobyte – 1000 bytes TRS-80 – 4K RAM (1977) Megabyte – 1,000,000 bytes 30 phonebook pages 1987 Desktop Gigabyte – 1,000,000,000 One movie 1997 Desktop Terabyte – 1,000,000,000,000 5,500 copies of every phonebook in the world 2013 Desktop Petabyte, etc Not in use other than stacked TB storage

Magnetic HDD PATA (IDE) SATA SCSI SSD Hybrid

Magnetic

Magnetic FDD 8” 5.25” 3.5”

Optical CD WORM R/W DVD Blu-Ray

Price/Performance Modern Memory Hierarchy CPU Chip Core Registers Cache • access time: 0.5-2.5ns • cost: ~$5000 per GB Level 1 Cache Level 2 Cache Level 3 Cache DRAM DRAM Memory • access time: 50-70ns • cost: ~$20-75 per GB USB Flash Memory • access time: 70-150ns • cost: ~$4-12 per GB Mechanical Disk Magnetic Disk • access time: 5-20ms • cost: ~$0.02-2.0 per GB Tape

History 1928 – Mag Tape 1956 – Hard Disk 1966 – DRAM 1970 – Bubble Memory 1976 – 5.25 FDD 1981 – 3.5 FDD 1984 – CD ROM

History 1994 – Flash Memory 1995 – DVD 1995 – CD-RW 1999 – Microdrive 2003 – Blu-Ray 2004 – Cloud 2009 – SSD 2010 – Hybrid ????