The arithmetic/logic unit gives the chip its calculating ability and permits arithmetical and logical operations. The registers are temporary storage areas that hold data, keep track of instructions, and hold the location and results of these operations.
Basicly, we have only two possibilities: INTEL & AMD. The third- Taiwan company VIA with chips C3 is not the real alternative. The basic measurement of quality of CPUs is their frequency. In this times the common processor works at the speed of about 1 GHz. But also CPUs
with speed of 2.5 GHz are available. 3. RAM

Computer systems can store data internally (in memory) and externally (on storage devices). Internally, instructions or data can be temporarily stored in silicon RAM chips that are mounted directly on the computer’s main circuit board, or in chips mounted on peripheral cards that plug into the computer’s main circuit board. These RAM chips consist of millions of switches that are sensitive to changes in electric current. So-called static RAM chips hold their data as long as current flows through the circuit, whereas dynamic RAM (DRAM) chips need high or low voltages applied at regular intervals—every two milliseconds or so—if they are not to lose their information.





Memory circuits are very important parts of PC composition. They determine the speed of giving the data to CPU and greatly influence the whole performance. Contemporary, there are 3 moduls available: old, low-end, but cheap SDRAM, from them coming quick and modern DDR SDRAM and finally revolting RDRAM.



4. Main-board

If the common users have chaos between PC components, it's for sure the main-board. About twenty different chipsets are currently available and when we add some tenths manufacturers, we can easily achieve number 100.
The function of motherboard is to support CPU and to connect it with the other components. It contains some slots, where the cards are put. AGP supports modern graphic accelerators, PCI sound cards, internal modems, older graphic cards. IDE slot is now not actual. Also BIOS and CMOS clock are arranged there.
The motherboards differ in the speed of SYSTEM BUS. It determines the speed of giving and receiving data from and to CPU (the best ones 400 MHz). The size of main-board is important. You will not implement old AT board into ATX case.
Some boards have also sound card included.