1.3 Under the Covers

• The five classic components of a computer are input, output, memory, processor (datapath and control)
• The memory is where the programs are kept when they are running; also contains the data needed by running programs
• Datapath performs arithmetic operation
• Control manages memory, I/O according to program's instruction
• Two basic types of memories: DRAM and cache
• RAM means memory accesses take the same amount of time no matter what portion of the memory is used
• Cache memory consists of a small, fast memory that acts as a buffer to DRAM
• The use of layers or abstractions is a principle technique for designing very sophisticated computer systems
• Instruction set architecture is the abstraction for interface between hardware and lowest level software
• Volatile memory loses data when it loses power - hold programs while they are running (Main or Primary Memory ie. DRAM)
• Nonvolatile memory - store programs between runs (Secondary Memory)