Shared PCI/ISA Slot



If you look at the picture above, you will see two slots, an ISA slot and a PCI slot. The problem is there is only one expansion slot available on the back of the case. With this expansion slot you can choose either to use an ISA card or a PCI card, but not both. That is the reason it is called a shared PCI/ISA slot. You must choose one, or the other type of expansion card. This is a good place for a modem since modems are about 50/50 ISA and PCI. Below is a picture of an ISA modem.


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Notice that the modem has its own speaker. When you connect to the internet and hear the modem dialing, it is this speaker that you hear the sound coming from. Modems are what convert our computer's digital data, into analog waves, so that the data can travel through the phone lines to another computer. The other computer's modem then converts the analog waves back into digital data, so the other computer can understand it. Modems are rated by how many bits per second they can transmit and recieve data. Just because a modem is rated at 56K (56,000 bits per second), does not neccesarily mean that it will be able to send and recieve at this speed. Phone lines and your internet provider also play a big part in how fast your computer can recieve and send information via the internet. Many, if not most, phone lines are only capable of transmitting at 28.8k. For this reason, even though most internet providers offer a 56K connection, your only going to be able to access this service at 28.8k, if your phone lines limit your connection speed. Below is a picture of a PCI modem.




RAM



RAM is simply an abreviation for Random Access Memory. Above is a 128Mb SDRAM chip. Haven't I explained SDRAM yet? :-) Ok sorry... SDRAM is simply another abreviation which stands for Synchronous Dynamic Random Access Memory. In other words... It's a newer, better type of memory, so we need a newer, better abreviation to make things harder on us! :-) The newer memory is capable of performing effectively with the newer, higher data transfer, bus speeds, of 100Mhz and faster. A bus is simply a connection between two items on the motherboard. The data transfer speed is how fast the data travels between the two items. SDRAM modules usually are available in 16Mb, 32Mb, 64Mb, 128Mb, and 256Mb sizes, each able to hold different amounts of data. The 16Mb module can hold 16M, (or 16,000,000) bytes of data. The 256Mb module can hold 256M, (or 256,000,000) bytes of data, (16 times more than the 16Mb module!). The memory module shown above is composed of several DIMM chips. DIMM stands for Duel In-line Memory Module. DIMM's have seperate contact points on both sides of their boards; although, the older SIMM's (Single Inline Memory Modules), were connected to each other on both sides, making both sides have the same connection. The more DIMM chips on a module, the more memory it has, as long as the DIMM chips have the same memory capacity. Common DIMM chip capacities are: 1M, 2M, 4M, 8M, and 16 megabytes of memory each. Below is a picture of a single DIMM chip.



A computer's memory is like a person's memory, the more it has, the more it can remember. Most computers available today have memory capacities of 32M to 128M. Quick question; if you have 4 4M DIMM chips on both sides of a SDRAM module, or 4 8M DIMM chips on on side of a SDRAM module, how much memory would you have? If you guessed 32M your right because 4 x 4M x 2 sides = 32M. Also 4 x 8M x 1 side = 32M. Pretty easy huh?
Power Supply



The power supply supplies the fuel (power), for the computer. It supplies power to the motherboard, the drives, and also, normally, contains a fan that helps assist in the task of cooling the computer. The power supply shown has an additional outlet available for another device like a printer or scanner. Power supplies come in a variety of wattages. 200 watt and 250 watt, are probably the most commonly used power supplies. I prefer a 300w, 350w, or even higher wattage, because they are not that much more expensive, and will provide a more powerful supply of electricity for your computer.
Power Cable Connector



The Power Cable Connector is what connects the power supply cable to the drives. Once plugged into the device, it furnishes power to run the CD-ROM, Hard Drive, or any other drive.





Power Cable



The power cables supply power from the power supply to the drives. The power cables are red, yellow, and black. The yellow wire furnishes 12 volts of power. The red wire furnishes 5 volts of power. The two black wires are ground wires for each. Some drives, like the floppy, use a smaller cable and connector, but their wires are still the same voltage.



PCI Slot 3



PCI slots can handle 64 bits of data at a time, where ISA slots can only handle 32 bits at a time. PCI stands for Peripheral Component Interconnect. A 64 bit PCI slot or (PCI bus), has 64 connections to the motherboard. Each connection is capable of handling 1 bit of data at a time. A 32 bit ISA slot has 32 connections to the motherboard and can handle only 32 bits of data at a time. Below is a picture of how a PCI card is installed.
Note: Older technology ISA slots were 8 and 16 bit. The newer EISA or "Extended ISA" are capable of 32 bit data transfer. It's also worth mentioning that older PCI technology was 32 bit. Newer technology is 64 bit.



Below is a picture of a SCSI PCI expansion card. SCSI stands for Small Computer Interface System. With a SCSI expansion card, you can connect anywhere from 7 to 15 different devices to one SCSI connection. SCSI is one of the fastest data transfer interfaces available. SCSI cards are available with transfer rates from 4MB per second, up to 80 MB per second. The LVD Ultra2 SCSI interface is the fastest, with an 80MB/sec data transfer rate. LVD stands for Low Voltage Differentiate. Below is a picture of a PCI SCSI expansion card.



PCI Slot 2



PCI slots can handle 64 bits of data at a time, where ISA slots can only handle 32 bits at a time. PCI stands for Peripheral Component Interconnect. A 64 bit PCI slot or (PCI bus), has 64 connections to the motherboard. Each connection is capable of handling 1 bit of data at a time. A 32 bit ISA slot has 32 connections to the motherboard and can handle only 32 bits of data at a time. Below is a picture of how a PCI card is installed.
Note: Older technology ISA slots were 8 and 16 bit. The newer EISA or "Extended ISA" are capable of 32 bit data transfer. It's also worth mentioning that older PCI technology was 32 bit. Newer technology is 64 bit.



Below is a picture of Creative's Sound Blaster Live Value PCI sound card. The sound card is what processes the sound data. When you hear music coming from your computer, something inside has to be handling this sound data. The sound card is responsible for what you hear coming from your computer's speakers. The better the sound card, the better the sound. The Sound Blaster Live Value card allows you to connect a microphone, an input device (like a musical keyboard), front speakers, and rear speakers which combined with the front, give you superior surround stereo sound. Just like the video card, the sound card has it's own processor in charge of managing the sound data.



PCI Slot 1



PCI slots can handle 64 bits of data at a time, where ISA slots can only handle 32 bits at a time. PCI stands for Peripheral Component Interconnect. A 64 bit PCI slot or (PCI bus), has 64 connections to the motherboard. Each connection is capable of handling 1 bit of data at a time. A 32 bit ISA slot has 32 connections to the motherboard and can handle only 32 bits of data at a time. Below is a picture of how a PCI card is installed.
Note: Older technology ISA slots were 8 and 16 bit. The newer EISA or "Extended ISA" are capable of 32 bit data transfer. It's also worth mentioning that older PCI technology was 32 bit. Newer technology is 64 bit.



As technology changes, improvements to computers and hardware are made. Below is a picture of a Promise PCI expansion card that allows you to connect up to four additional drives to your computer. Thats not all! This new expansion card allows sustained data transfer rates up to 66,000,000 bits per second (66Mb/sec). This newer technology is known as Ultra ATA/66. ATA stands for Advanced Technology Attachment. What does that mean? Well Ultra ATA/66 is the same as Ultra DMA/66. Still don't know what it means? (Don't feel bad I had to look it up).;-) DMA stands for Direct Memory Access. The Ultra ATA/66 (or Ultra DMA/66), can directly access the memory, transfering 66M bits per second. WOW!



PCI Audio Accelerator



This is the PCI Audio Accelerator. It is a "helper" chip that increases, (or accelerates) the transfer of sound, (or audio) data. It also helps enhance the quality of the audio data. Motherboards commonly have several "helper" chips like this, that assist the Chipset in routing, directing, and enhancing the flow of data.
Panel Connector Cables



The panel connector cables connect the front panel to the motherboard. The front panel is where the hard drive activity lights, case speaker (normally), reset button, on/off button, computer power on light, and key lock (if applicable), are located. These items must be connected to the motherboard like everything else in order to function. Below is a view of the panel connector cables inside a different computer.



Case Speaker



Although the clickable image does not look like a speaker to me either, ;-) I will at least use it to explain the function of the case speaker, which is not visible. According to the motherboard specifications for this board, this is an optional speaker, which hopefully no one will be silly enough to buy! :-) Seriously though, most cases come with a case speaker. The case speaker is usually located behind the front panel and is only used for computer warning beeps, or an occasional generic sound from a program. You rarely ever even hear the case speaker, and can sometimes bypass it through your regular, "good" speakers. The sound card I use allows you to connect the computer's case speaker output wires to it, so that it plays the beeps, and makes the case speaker obsolete. There is nothing wrong with using the case speaker; although, the regular speakers are able to handle more wattage, but you really don't need it for the beeps.
Optional Case Fan



Adding an optional case fan is a good idea for maintaining a cool computer. Optional fans are usually quite inexpensive. They assist the case fan, sharing the cooling duties.
BIOS
Basic Input/Output System



BIOS stands for Basic Input/Output System. Above is a built in BIOS program that is always available on a computer. Without any disks or even a hard drive, the BIOS is always there, written permamently on the BIOS chip. It is used to set up the computer's hardware. Everytime you boot your computer, you have the option of entering "Setup." Setup is where you access the BIOS program. Only experienced users should alter the BIOS settings. Improper BIOS settings can cause major problems on a computer. The BIOS chip contains enough information to operate the computer by itself. When the computer is first turned on (booted), the BIOS program is in charge. After booting and performing a few system checks, the BIOS turns the computer over to your operating system. Windows 98 is an example of a common operating system. CMOS, which stands for Complementary Metal Oxide Semiconductor, is where the BIOS stores it's information. The CMOS area is usually located on the Chipset, or the Real Time Clock Chip (not the CPU clock). The Award BIOS Chip also allows you to save your settings into EEPROM. EEPROM stands for Electrically Erasable Programable Read Only Memory. Read Only Memory (or ROM), normally is just that, and can never be erased or changed. ROM memory retains its data even when the power is off. EEPROM memory also retains it's data when the power is off, but it can be altered by electrically erasing it, so that new data can be entered. If the CMOS loses it's BIOS data, the EEPROM can provide your BIOS with a backup copy of the computer's settings. Below is a picture of a BIOS chip. This chip is where the BIOS progam is stored.



Motherboard



The motherboard is kind of like the blood vessels inside the human body which connect to all the vital organs. Instead of blood vessels, the motherboard uses tiny electrical paths to connect each component of the computer. The motherboard is what ties everything together inside the computer. The Chipset (2 chips on this motherboard), manage and direct the flow of data between the components. The BIOS is where the computer's settings are stored and changed. In the picture of the AOpen AX6B Motherboard above, you can see most of the connecting slots, ports, and connectors. Each is labeled to show which component it connects to. Motherboards are judged primarily by their chipsets; although, the BIOS, and the type and amount of expansion slots are also important.
Microprocessor



The microprocessor is the brain of the computer. The picture above shows a microprocessor with heatsinks and a fan, which prevent it from overheating. Below is the microprocessor without the fan or heatsinks, being inserted into a Slot 1 motherboard connection.



The microprocessor contains the Central Processing Unit and it's cache memory. The Central Processing Unit or CPU, contains the Control Unit and the Arithmetic/logic Unit, both working together to process the data inside the computer. The control unit is actually the brain of the brain. The control unit controls the computer by fetching, decoding, executing, and storing the data inside the computer. The arithmetic/logic unit is kinda like the CPU's sergeant. It handles all the math calculations and logical comparisons for the CPU, working together with the control unit like team. The microprocessor's Level 1 cache memory, is memory that is contained within the CPU, and stores the most frequently used instructions and data. The CPU can access the cache memory much faster than having to access the RAM (Random Access Memory). Below is a picture of what's inside a Pentium 3 processor. The CPU and Arithmetic/Logic unit are contained within the center chip. Level 2 Cache memory is visible on the right.



Level 1 cache memory, is memory that is included in the CPU itself. Level 2 cache memory, is memory between the RAM and CPU, but not directly on the CPU chip itself. The above photo shows level 2 cache memory on the Processor, beside the CPU. Below are two photos of a CPU (Central Processing Unit). The photo on the bottom is the CPU chip from the outside. The photo on top is a large road map of the inside of the CPU, showing the different areas, and what their function is. See if you can find the areas that fetch, decode, and execute the data. Can you also find the cache areas that store information? The Pipelined Floating Point area, Logic areas, and Superscalar Integer Execution Units area are part of what? Did you guess Aritmetic/Logic Unit? If so, your right! The Control Unit is in charge of decoding, executing, storing, and fetching data. The Control Unit first fetches the data from memory. It then decodes the data so the computer can understand it. Next it has the Arithmetic/Logic Unit proccess this data by executing it, and storing it back into memory. These 4 steps are what's called the Machine Cycle of a computer. These 4 basic steps are how the computer runs each and every program.



At the top you can also see the Clock Driver. The Clock Driver is what times, or sets the pace for the computer. The clock's speed, is how CPUs are rated. Each machine cycle consists of two beats. Each beat the Control Unit fetches and decodes data, which is called the Instruction Cycle. At the same time the Arithmetic/Logic Unit executes and stores data, which is called the Execution Cycle. The speed of a clock is rated by how many beats per second it can accomplish. 1 million beats per second is refered to as 1Mhz. For every beat (except the very first), a machine cycle is completed. Common CPUs available today perform at 550Mhz and faster. This means that a 550Mhz CPU can execute 550,000,000 instructions in a single second! Man! I do good to get two things done an hour! ;-)
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