Transcript Slide 1
Introduction to Computers Just what is a computer anyway? What is “Software” or “Hardware”? Software is purely an explicit set of step by step instructions for a computer to follow on command. While you can hold a diskette that has software on it, or a book about it, it really only exists in the electronics in the form of ones and zeros and then only as long as there is power available. Hardware on the other hand, is something that you can physically touch like a monitor, a mouse, the keyboard and so on. To understand how a computer works think of a light switch. You can either turn the light off or on. In computer language it is either a zero (0) or a one (1). A single switch doesn’t do much for us but if we take 8 switches and gang them together like this example; now we have a code that can be assigned to a letter or symbol. For example the combination of 01101000 = h Which = 0 OR Which = 1 01101000 = =h 01100001 = =a 01110100 = =t Would be seen by a computer as: 011010000110000101110100; but by humans as: hat Since we have 8 switches we can have 256 different combinations. (mathematically that’s 28 ). That’s enough to assign all 26 letters of our alphabet twice (upper and lower case) all 10 numbers of our base ten number system and still have plenty left over for symbols like ? / : ; - _ etc. 2 raised to the 8th power is 256 2, 4, 8, 16 ,32, 64, 128, 256 Each set of 8 switches is called a “BYTE”, therefore one Byte means one of our characters. A computer is not really smart at all, it is just blazingly fast. And that is how it does all the amazing things for us. It processes steams of 1’s and 0’s very quickly and is getting faster and faster as the volume of data it can process increases 10010100 10010100 00011101 00011101 11100000 11100000 Computer 1985: 4,700,000 bytes per second both ways on a 2 lane highway 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 In the 90’s, 400,000,000 (Million) bytes per second down a 8 lane highway to a single computer. Intel Pentium etc. 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 In the early 2000’s, 1,200,000,000 (billion) bytes per second down a 32 lane highway to each of 2 computers working together (Dual Core) 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 10010100 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 00011101 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 11100000 Today, 3,000,000,000 (billion) bytes per second down a 64 lane highway to each of 4 computers working together (Quad Core) The CPU is the actual computer chip. CPU stands for Central Processing Unit and is the brains of the computer. It is very much like you working at your desk. That phone doesn’t get answered or paperwork done if YOU don’t do it. Same with a computer. EVERYTHING the computer does is done by the CPU. When we use the term computer, we are really talking about the whole thing; the box, the monitor, keyboard, etc. “I just bought a new computer!” Well, technically that is a correct statement because the CPU is really the “computer” and it IS inside the case, so yes, you did buy a new computer. These days, it is commonly accepted to refer to the entire system as “a computer”. In the world today, there are thousands of examples of computers surrounding us at all times. Just in my truck to come to work there are 28 different computers controlling everything it does. This morning, my coffee pot began brewing my coffee promptly at 6 am, my “Smartphone” woke me up at 7 am and I used the remote control to turn on the TV to watch the news. But, If we forget about industrial and appliance computers and just focus on personal computers there are basically five different configurations available. Desktops (Towers) Laptops Notebooks (Mini Laptop) Tablets (I Pad) Smart Phones Memory (RAM) Memory = Computer’s Desk Top This is where all the work is actually done by the Computer Chip (CPU) just like you do sitting at your desk. You move things around, you write, you answer the phone, you staple stuff and so on. The CPU does too. The bigger the desktop, the easier it is for the CPU to work and therefore the faster the work will progress. Just like you, if your desk is bigger, you don’t waste a bunch of time looking for stuff that you are working on because it is more spread out instead of in stacks. Unlike you, the computer can’t stack stuff up so when it runs out of space on the desktop, it eliminates what spills off or it will stop running and give you an “Out of Memory Error”. Memory is measured in Bytes. One Byte = 1 character like the h in the previous example. A thousand bytes (or characters) = One Kilobyte or 1 K. A million bytes would be one Megabyte (Meg) and in today’s world we deal with Gigabytes of memory which is a Billion. A typical laptop, for example, will have between 2 to 4 “Gig” of memory installed when you buy it. That would seem to be a lot of desk space but later we will see it is necessary. One thing is important and that is Memory is volatile which means that when you shut off the computers power anything that was “in memory” (on the desktop) is gone forever… Storage Space A Hard Disk is just an Electronic File Cabinet When you buy a computer, the three most important things to consider are: 1. How much Memory does it have? 2. How Big (capacity) is the Hard Drive? 3. What kind of Virus Protection is loaded? The rest is just fluff and pretty stuff. Hard drive size is measured in bytes too but in this case we are talking about storage. How many bytes can be stored on it? In today’s world, this capacity will be expressed in terms of Gigabytes. A typical laptop purchased today will have a hard drive of between 160 to 250 “Gig” which is a Whole lot of characters. Remember one byte = 1 character. It took 32 bytes to write that sentence (a space is a byte too), go ahead, count them; don’t forget the period. If you stop and think about it. The Novel “War and Peace” only has 3.1 million characters in about (500,000) English words. It would easily fit in one tiny corner of your 250 Billion character hard drive in your new laptop. As a matter of fact, I could easily load it onto my 8 Gig Droid or an I-phone along with a hundred other books and read it during breaks. Unlike Memory, a disk is NOT volatile and your data does not go away when you remove power. It stores characters for you just like a file cabinet stores documents and they will stay there forever or until you delete or move them…just like a file cabinet. It does it because the one’s and zero’s are stored magnetically instead of electronically like they are in memory. A Hard Drive is: Actuator arm Tiny air gap Aluminum platter Read/write head An aluminum platter with an iron oxide coating in concentric circles An actuator arm moves in and out to align an electromagnetic head above the circles of iron oxide The electromagnetic read/write head at the end of the arm either magnetizes (writes) or senses the magnetic state (reads) of the tiny spots in the iron oxide. The read/write head is an electromagnet If a spot is magnetized, it becomes a One. If it is not magnetized, it is a Zero. Once magnetized, the spot stays that way because it is an iron oxide spot and therefore independent of electricity so power can be removed without affecting the magnetism of that spot. As the disk spins very fast, the actuator arm moves the head in and out precisely aligning the head over a specific circle of iron oxide. Then the CPU commands the electronics to either magnetize or demagnetize a particular spot to “Write” a 1 or a 0. OR, in read mode, it senses whether a specific spot is a 1 or a 0 and reports that back to the CPU. When the CPU puts the 1’s and 0’s in groups of eight, we get the “Bytes” we need to form our words… 01101000 01100001 01110100 = hat. Obviously, this all occurs at speeds we cannot begin to comprehend so while the CPU is processing individual bits (a 1 or a 0), combining them into bytes and converting those into words for us, we simply perceive the finished product. The important thing to remember is that the spots are magnetic instead of electronic and therefore “permanent” for all intent and purpose. Once magnetized, a spot stays that way until we tell it to demagnetize. That is why hard disks are considered permanent storage. A CD and a DVD look exactly alike to a human, but…. A CD or DVD is made up of several layers of plastic that is 1.2 mm thick. Each layer of the disk is impressed with billions of tiny pits. These pits are where all the video, audio, and text data is stored. When the disk is inserted into a reader, it reads these pits, interprets the data and sends it to the CPU. On the DVD the pits are much smaller and far more numerous therefore they can store much more data. CD One DVD Zero The single most important element in the reading of a DVD is the laser. A DVD reader's laser beam is reflected off the aluminum layer of the disk and hits or misses the optical pickup (detects any changes in the light). The pits reflect in a different fashion from the flats (non pits) which is interpreted as a one or a zero. The illustrations show the laser hitting a pit and then hitting a flat (non pit). Notice it misses the pickup in the non pit area thus a zero. A tracking and timing mechanism is required to keep the laser moving across the disk in a precision manner. It is critical that the beam stay centered on the individual tracks as the disk spins past it. Working much like the actuator in the hard disk, the laser is precisely positioned and the reads timed. Look closely at the disk representations above and you will notice the pits are slightly elongated and curved. That accounts for the spinning of the disk past the head. You may also notice that the pits and flats get closer together as the disk moves towards the center. Physics tells us that as you get nearer the center of the disk, the apparent speed increases so the pits and flats pass under the laser more quickly. That is what the tracking and timing circuits do. They keep the data to the CPU coming at a steady and reliable rate. The Motherboard is where all of the components plug in. This one is for a Tower. In laptops, net books, touchpad's and cell phones, the video, audio and so on are much smaller and usually built into the motherboard. CPU NOTE: The Hard Disk and other drives are mounted on the Chassis along with the power supply, fans, power switch and so on. Memory Inputs and Outputs like USB, Sound, keyboard, mouse, monitor and etc. present out the back of the tower. Referred to as “Daughter Cards” In reality, there will be a very large heat sink and fan mounted on top of the CPU due to all the heat the CPU generates as it works. Heat is a real problem in the smaller devices. Network Card Sound Card Video Card TV Tuner Back edge Other cards And So On Front edge Motherboard of a Tower Style Computer External (portable) storage devices Over time from 1967 with the introduction of the 8 inch floppy disk to today, the floppy disks have gone through many evolutions and developments resulting the 3 ½ HDD that is still in use today but fading fast in favor of the Flash Drive Today Today Floppy disks require the use of complex and large disk drives. They are susceptible to damage and they are magnetic in nature making them vulnerable to strong magnetic fields. Not to mention that they are very limited in capacity to a maximum of 144 megabytes. Flash drives eliminate or reduce those weakness’s since they are not magnetic, plug directly into a computers USB connector and are encased in tough plastic shells. Their capacity is more closely related to hard drives and can go up to 64 Gigabytes (so far). It is easy to understand why flash drives have all but eliminated floppy disks in today’s world. Anatomy of a 3 ½ diskette The basic internal components: 1. Write-protect tab 2. Capacity indicator 3. Hub 4. Shutter (covered head access) 5. Hard plastic housing 6. Lubricated fabric protection 7. Magnetic disk 8. Disk sector. (part of a track) Although you would be hard pressed to buy a computer today with a floppy disk since Flash Drives offer so much more capacity, they are still in limited use and are still available in stores. In the bottom figure you can see the rings of magnetic material which are called “Tracks”. These tracks are further subdivided into “Sectors” to accommodate timing and sequence requirements. Item 8 shows one of these sectors. The shutter would be opened by the drive when the disk was inserted and then the actuator arm could position the read/write head over that opening to access the tracks and sectors. The real purpose of the shutter is to protect the diskette when it is not in the drive. The hub is designed to engage the drive motor to spin the disk at a specific speed thus establishing a precise timing and reference signal. The two holes at the top tell us that it is a 1.44 Meg floppy and the hole on the left has a small plastic door that can be closed to “Write Protect” the disk preventing erasure of data. Flash Drives have replaced Floppy disks for portable storage in today’s world A flash drive is a non-volatile storage device that can be electrically erased and reprogrammed. Flash drives are similar in nature to conventional hard drives but they have no moving parts, are encased in a tough plastic shell, easy to carry in your pocket and have a vast storage capability (from 512 meg to 64 gig presently). Flash drives come in all kinds of shapes, even on a Swiss Army Knife with Security It is generally worth the money to get one with iron clad security if it has personal data stored on it along with pictures and documents So what have we learned so far? In general there are five different configurations of personal computers as shown . Of these, the tower is becoming somewhat obsolete as people turn towards portability. Desktops (Towers) Laptops Notebooks (Mini Laptop) Tablets (I Pad) Smart Phones Computers are not really smart and cannot do anything on their own, (autonomous) like in the movies. They can only follow instructions we give them. They just do it VERY quickly. The four most important considerations when buying a computer today: 1. How much Memory (RAM) is installed? 2. How big (capacity in bytes) is the hard drive? 3. How fast is the CPU? 4. What virus protection is installed? (DO NOT GO WITHOUT IT AND KEEP IT UPDATED !!). Other considerations to think about; 1. How many USB ports (at least 3) 2. Wireless connection of 8.2 N or better (3G or better for smart phone). 3. Battery life and is a bigger battery available (consider buying an extra). 4. Blue Tooth capable (wireless mouse, headset, etc.) Accessories to consider, especially with laptop or mini; 1. Wireless and/or Blue Tooth Mouse 2. Extra battery (and the largest capacity available for the machine). 3. USB HUB which allows additional USB devices to be connected. 4. Protective carrying case with pockets for accessories and papers. 5. Docking station, external monitor and full size keyboard if stationary a lot. About Software Remember that software is the intangible that you cannot see or touch. It is the instruction set that exists in 1’s and 0’s but only as long as there is power on the device. It can be compared to the spoken word. You might hear “Ask Not What You’re Country…” and remember it but once the words have been spoken, they are gone. They cannot be touched or seen but they leave a lasting impression. In a computer, you see or hear the RESULT of the instruction set but you cannot touch or see the actual instruction. The most important software for a computer is THE OPERATING SYSTEM and must be installed before anything else will work. Today, that is most commonly WINDOWS 7 but there are lots of machines still using WINDOWS XP which is an earlier version. (Note: Apple computers have a different system). Compare the operating system to the foundation of a house; nothing else can be built until the foundation is there. The operating system establishes all the rules and sets the framework for all other software and hardware to function within the system. Once the Operating System is in stalled, we can install MANY types of software; 1. PRODUCTIVITY: Word Processing, Spreadsheet, Presentation, Publication, etc. Examples are Microsoft Word, Excel, PowerPoint and Publisher. These are typically bundled together like Microsoft Office 2010. 2. SOCIAL: Face book, Twitter, My Space, Friend Finder, EBay, Craig's List, E Harmony, etc. Software that allow interactive interface between people for any number of human activities. 3. GAMES: Vast array of games either adapted to or built specifically for the computer. Everything from Solitaire to Worlds of War craft and everything in between. 4. UTILITY: Software to manipulate, save, duplicate etc. pictures and video 5. DRIVERS and COMMAND: to interface with printers, scanners, external drives, USB equipment, etc.