Computer Hardware Basics CIS 110 Is This Greek to You? From a Dell advertisement: Conceptual Real Computer Processor CPU chip Intel Pentium4 2.8GHz, 533MHz FSB Primary Memory Storage 256MB DDR SDRAM @ 400MHz Secondary Disk Storage 40GB Ultra ATA/100 HD 7200RPM CPU • Central Processing Unit, now all in one microprocessor. • Three Types of Tasks: 1. Move data between various parts of system. 2. Perform arithmetic operations. 3. Perform logical comparisons for decisions. • #1,2 done by Control Unit(CU), #3 by Arithmetic-Logic Unit (ALU). • Other units for subtasks. Compatibility • Instruction Set – the set of available operations and the way they are encoded in binary. • Software must be written with those same kind of machine-level instructions to run. • Intel and AMD are both x86 compatible. • Macintosh PowerPC chip is not. • Backwards compatible: as new features added, are old instructions still supported? • Wintel • Hardware compatibility? CPU Performance • Clock speed is most obvious indicator, 3GHz is faster all else being equal. • Clock sets the pace and synchronizes components. Think metronome, drummer in marching band. • Other differences in architecture affect amount of work done per „tick” of clock. Intel <> AMD! • Benchmarks – real world performance. • Cache memory, Parallel Processors Prefixes Kilo_ Thousands of… KB of RAM in early micros Mega_ Millions of… MB of RAM in PCs today Giga_ Billions of… GB on HD, GHz CPU clock Tera_ Trillions of… TB of data in large systems Main Memory • Some form of RAM – Random Access Memory, freely read/write • Storage capacity in Bytes – most 256 or 512 megabytes (MB) (Mb is megabits) • Also speed issues – DRAM – SDRAM – DDR double data rate • Speed comes at price of volatility. Specialized Memory • Other type is ROM – Read Only Memory • Contents cannot be changed. Data “locked” in at manufacture. • Is non-volatile – data not lost when power is lost. • Used in PCs mainly for BIOS, Basic Input Output System, startup instructions for PC. • Does NOT neatly fit our primary/secondary model. • Flash – specialized type that can be erased in special mode. Disk Drives • Hard disk contains dormant programs, data. • Processor cannot use contents directly, must copy into memory first. • Much, MUCH slower compared to processor and main memory. • Larger/faster disk normally does not make machine much faster as a whole. • Installing s/w just copies from CD to HD. How It Works: Running a Program 1. Instructions of the program are loaded into memory from the disk. 2. Processor fetches first instruction. 3. Decoded and Executed: a. Data moved by Control Unit b. Small ultra-fast storage onboard CPU: registers c. Arithmetic & Logic operations on ALU 4. Writeback results to memory, other device. 5. Fetch next instruction until terminate. How It Works: “Booting” the PC 1. System power-on. 2. BIOS instructions executed 1. Check h/w configuration has not changed. 2. Self-test of h/w POST beeps 3. Access boot sector of hard drive. 4. Load Operating System kernel into memory. 5. Pass execution (and control) to O/S. BIOS Screen Access by <Del> during boot… Motherboard • Mobo connects CPU & RAM with all other system components. • CPU and RAM installed in sockets or slots. • External devices plugged into ports at rear. • Adapter boards installed into internal slots on a bus. Real Motherboard A micro-ATX ASUS motherboard for AMD Athlon CPU More on Motherboards • Motherboard choice depends on CPU choice – and vice-versa. • Cheaper? Less chance for future upgrades. • Cheaper mobo more likely to have integrated video, audio – but very basic. • Motherboard form factor – size & shape, mounting. • Case & power supply • Drive bays, etc. Inside a PC Case System Performance • Role of CPU cache... Reduce # fetches from RAM • More cache = more performance at same clockspeed -- Celeron versus Pentium • Disk space can be used as virtual memory if RAM is low – but big performance hit. • Adding more memory means fewer trips to SLOW hard disk. • Win XP: 128MB (yuck), 256(ok…), 512(cool!), 1024, 1 GB – little gain for most Which is faster? Why? Consumer Issues • How fast is fast enough – for you? • What to upgrade? – Usually more memory first. – Faster 3D video card for gamers? – Faster CPU, RAM depend on motherboard. • Upgrade or buy a whole new system? • Desktop versus Laptops – What is sacrificed to gain portability? Buzzwords • Over-clocking • “Modding” A Reminder… We have focused on PCs, but… these fundamental issues apply to all computers. Putting It Together • As a computer-shopping consumer you should now be able to better understand and compare the specs for different PCs • Go to Dell.com and examine low-end and high-end PCs.