CPU - Central Processing Unit Control Unit ALU Registers PC IR
	Memory
	Bus
	Instructions Register - memory Register - register
	Data Path Registers ALU buses Data path cycle
	Instruction Execution - Fetch-Decode-Execute Fetch from memory into IR Change PC Instruction type? Memory required? Fetch data if needed Execute Repeat
	Interpreted instruction sets... Fix incorrectly implemented instructions in the field or make up for design deficiencies Add new instructions a minimal cost Structured design: efficient development, testing and documenting
	RISC vs. CICS Smaller instruction set initially (R) Simple instructions that can execute in one cycle of the data path (R) Backward compatible (C) Combine RISC for common instructions, complex instructions less common (C)
	Design Principles Common instructions executed by hardware Maximize the rate at which instructions are issued Instructions should be easy to decode regular fixed length small number of fields fewer instruction formats Only loads and stores should reference memory Provide lots of registers
	Pipelining, dividing instruction execution into stages Fetch Decode Operand Fetch Execution Write back
	Multiple pipelines
	Superscalar Architecture - multiple functional units
	Array Processors
	Vector Processors
	Multiprocessors
	Multicomputers
	Main memory Bits BCD Memory addresses Byte order Big endian (byte numbers left-to-right) Little endian (right-to-left) Error correcting codes Cache Memory Economics - fast memory expensive Most heavily used memory words kept in fast memory Locality principle Mean access time = c + (1-h)m {c-cache access time, m-memory access time,   h-hit ration (fraction of references found in cache)} Split cache vs. unified cache - split has instruction cache and data cache Memory Packages
	Secondary Memory Memory hierarchy Magnetic Disks Track, sector, preamble, error correcting codes, intersector gap Winchester disks, cylinder, seek, rotational latency Audio-visual drives don't do thermal recalibrations Disk controller Floppy Disks IDE - integrated drive electronics and Extended IDE (EIDE) SCSI - small computer system interface, high speed bus RAID - redundant array of inexpensive disks Striping, mirroring, parity drives, SLED - single large expensive disk Optical media CD-ROM Red book Yellow book Green book High Sierra (IS 9660) CD-R (Orange Book) DVD (smaller pits, tighter spiral, red laser)
	Input/Output Motherboard Controllers DMA Interrupt Bus arbiter Cycle stealing ISA bus EISA bus PCI bus Terminals Keyboards CRT Monitors LCD (passive matrix and active matrix) Character mapping vs. bit mapping 1024 x 768 x 24 bit color = 2.3 MB of video RAM RS232C Terminals Mice Printers - dot matrix, ink jet, laser Halftoning Color printers Modems ... ISDN
	Character codes ASCII Unicode