1. Anatomy of a Computer RAM, ROM, CPU, etc. Chapter 4 in Computing Essentials (O’Leary and O’Leary)

2. A chip off the old block zMillions of transistors are connected into what is called an integrated circuit or chip zChips are made from silicon (a semiconductor, a material halfway between a conductor and an insulator) z“Silicon valley” is a nickname for the region south of San Francisco that contains an unusually high concentration of computer companies.

3. CPU zThe most important chip in a computer is the microprocessor zThe microprocessor houses the Central Processing Unit (CPU), the “brain” of the computer zEx. The Pentium III is a microprocessor

4. Extending the brain analogy zSimilar to dividing the brain into yBrain stem yForebrain zWe divide the CPU into yControl Unit yArithmetic Logic Unit (ALU)

5. How good is your computer? zComputing means moving bits around, so an important question is how many bits can be handled at one time zWord size: how many bits are handled at a time (8, 16, 32, 64) by memory or the processor zBus size: how many bits can move around at once yanalogy: two-lane, four-lane or eight-lane highway zBus speed: how fast they move

6. How fast is it? zEach of the computer’s manipulations (instructions) begins with a “tick” of the clock zSo the faster the clock ticks, the faster the computer zClock speed: a measure of how fast the computer is, given in MHz (megahertz - millions of cycles per second) yThere are gigahertz machines now zMiddle number written on LaSalle’s computers

7. Speed II zSometimes one instruction can be started before the previous one was complete zLike have a batter on deck zSo another measure of speed is useful zinstructions per second, given in MIPS (millions of instructions per second) y(considered by some to be a misleading measure of speed)

8. The mother of all circuit boards zchips and other things are connected together on what is called a circuit board zthe mother board, a.k.a. the system board, holds the main components of the computer yCPU yclock yconnectors yexpansion slots, ETC

9. If you can’t stand the heat zThe chips, especially the microprocessor can get hot zheat sink: the strangely shaped metal or ceramic structure sitting on the processor that serves to draw away the heat zthere’s also a little fan near the processor; that’s often what you hear whirring away on old computers

10. A link to the outside world zThe process of putting information into or getting information out of a computer is called interfacing or input/output (IO) zports are sockets, typically in the back of a computer, where one plugs in the cable connecting the computer to the IO devices yNewer computers have a port in the front for convenience

11. Two types zserial ydata sent one bit at a time yfor modems and some printers ycable can be very long yex. MIDI, USB zparallel ydata sent eight bits at a time ylimit on length of cable yex. SCSI

12. SCSI port zSmall computer system interface zpronounced “scuzzy” zallows more than one device to be connected to a single port zdaisy chain: getting the output for a second output device from the first (rather than directly from the computer), the output for a third can come from the second and so on

13. A connector in every port zPorts have connectors, as do cables zconnectors come in two varieties ymale: have pins sticking out yfemale: have holes to receive pins

14. Analog to Digital zAny measurement that can be converted to an electronic signal (voltage or current) can be directly fed into a computer zthe original data is often continuous (analog) and must be converted into digital form zThis signal can be fed in through a port so long as the appropriate software is installed

15. In the cards zExpansion Slot: A socket designed to hold the circuit board for the device, such as a sound or video card, that adds capability to the computer system zAdapter cards: additional circuitry and chips that extend your PC’s capabilities allowing you to customize it

16. Some types of cards zvideo or graphics card: enhances computer’s ability to convert output into video and send it to the monitor zSound card: improves your computer’s sound capabilities, be it input (microphone) or output (speakers) zinternal modem: allows computer to connect to networks via phone lines and such

17. Plug and play zrefers to computer’s capability to figure out what to do when new expansion cards and devices are added zthis way the user does not have to know how to “configure” the system

18. Memories zSaving information we have entered (e.g. onto floppies) is referred to as “storage;” it is long term and slow by computer standards (storage  memory) zBefore we save the data, it is in the computer’s memory, i.e. in memory chips, which hold the information temporarily zMemory also holds the instructions a computer needs to operate (“stored program concept”)

19. Reading and Writing zThe basic actions involving memory are yWRITING: putting information into memory yREADING: getting information from memory zThe rest of the time memory just holds onto information

20. ROM zRead Only Memory zThis memory is loaded up by the manufacturer (some is programmable) zcontains low-level instructions for the computer zNot lost when the computer is turned off z“nonvolatile” memory

21. RAM zRandom Access Memory zThe memory the user uses zThe programs one loads and the data one enters are here zLost when the computer is turned off z“volatile” memory zWhy is it called random?

22. Random Vs. Sequential zA cassette tape is sequential access; you have to go through song one and two to get to song three zA CD is random access; you can jump directly to song three

23. Some Types of RAM zDynamic RAM (DRAM): dynamic means changing, which for memory is not necessarily a good thing, so dynamic memory must be continually refreshed ySynchronous DRAM: when the memory and a clock work together to send blocks of data more efficiently zStatic RAM (SRAM): doesn’t need constant refreshing, is faster but more expensive than dynamic

24. Cache zpronounced “cash” zThe computer puts information it anticipates (guesses) you will use soon in a place which is accessed more quickly zA correct guess is called “a cache hit”, an incorrect guess “a cache miss” zCaching improves speed

25. Some kinds of cache zMemory cache: put information from DRAM into SRAM (high-speed memory) yL1 on the chip with the microprocessor yL2 on a different chip zDisk cache: put information from storage (floppy or hard drive) into memory zBrowser cache: put information from internet into hard drive

26. Buffer zwhere data coming in (from input devices) or going out (to output devices) is stored until the transaction is complete zPrinter buffer: when you send something to print, it may not print right away, but instead sit in the printer buffer awhile yThere is usually an icon on the task bar indicating that you have something in the printer buffer

27. Clipboard zMemory location where data is placed during an application such as word processing (cutting or copying puts data on the clipboard); it is also used to transfer data from one application to another (e.g. from Excel to Word)