What is the "Microprocessor"? if you want to know more information than read below all details.

Which does the actual thinking inside the computer.
which microprocessor is used of the dozens currently available determines not only the processing power of the computer but also what software language it understands(and thus what program it can run)
opropcessors : An adjunct to the mircoprocessor,the coprocessor permits a computer to carry out certain operations much faster.A coprosessor can make a computer run five to ten times faster in some operations.
Memory :  Required by the by the microprocessor to carry out its calculations,the amount and architecture of the memory of a system  determines how it can be programmed and,to some extent,the level of complexity of the problems that it can work upon.
Bios ; The basic input/output system or BIOS of a computer is a set of permanently recorded programs routines that give the system its fundamental opernational characteristics.It determines what the computer can do without loading a program from disk and how the computer reacts to specific instructions that are part of those disk based programs.
Expansion Slots : They act as portals that allow new signals to enter the computer and directly react with its circuitry expansion slots allow new features and enhancements to be added to the system as well as permitting the quick and easy alteration of certain computer prerequisites,such as video adapters.
Support Circuitry : A Microprocessor,although the essence of a computer,is not a computer in itself(if it were it would be called a computer). It requires a number aof additional circuits to bring it to life:clocks,
controllers,and signal converters.Each of these  support circuits has its own way of reaching to programs,and thus helps determine how the computer works..

What is "System screws" and how it works? read more about it in article.

mere size is not the only factor determining the physicial compatibility of system boards however otherwise you  might  consider putting a smaller board into the box made for a larger one waiting to frustrate system boards are nearly the same size.the pattern of their mounting holes do not match.the variations often amount only to a fratction of an inch but they are enogh to prevent the easy substitution of one baord of an other.
IMB is amazingly frugal in the hardware used to hold its system boards inside their cases.as few as two screws hold them in place there are good electrical reasons for this miserliness with the hardware proper grouding being paramount among them, the balance of the mounting holes in the IBM's system boards are devoted to nylon fasteners which insulate the boards from the metal chassis while holding them in place mechanically the screws holds the IBM system boards in place,the nylon fasteners are designed to space the board vertically and fit special channels in the metal work of the case allowing the boards to slide into place.
IBM carried this same hardware frugality over to its,PS/2 line Although PS/2 planar boards wildly differ in shape and size between the various models they share the same parsimonious use of screws to hold them in place..

Some iformation about "System Board Replacement"

you'd have little reason to care about how big your motherboard is size has little influence on performance on the motherboard level(in mainframes and microchips size does count)The issue is physical compatibility.should you ever want to upgrade the performance of your computer by replacing its motherboard the best possible upgrade out side of replacing the  entire computer board size will determine what will fit in your case.if you are daring and want to save a few hundred dollars by getting a real lesson about how really simple PC's are by building one youself you will need to know that size inbox to put put every thing in.once you know motherboards are different sizes,the rule is in tuitively obvious,if you have an XT  size case you will need an XT size motherboard.

What is Oem boardmakers and system integrators? ,and how it work on your system?

The system boards wrought by other companies are both more and less diverse because of the nature of the industry.when it comes to the system boards inside their products,compatible computer makers fall into two types.those who design and  manufacture their own system boards and those who act as original equipment manufacturers or OEMs.
This meaningless term describes companies fabricating their products from the products of other companies.
some invest as little time and effort as it takes to put a nameplate on a finished product produced by someone else.others incorporate subassemblies into more powerful products and submit them to through testing these latter companies are also termed system integrators.
The difference between the OEM and the company that produces its own products is that you are likely to find the same system board inside many computers bearing the names of different OEMs.in many instances you will find nothing to distinguish them but the case or the label such computers are essentially interchangeable,termed by economists as commodities,and as with all commodities,the best of these look alike inside off the shelf computers in the one with the lowest price.

You have Memory issues? if you have than read our full article and know about more ..

Once the microprocessor had been decided upon the next choices were of memory,several aspects to be consiered.the working memory of the computer system must be deisgned both physically(what sort of chips should be used and how they should be
connected) and logically(what uses should the various memory locationns be put to)in addition mass storage the holding zone for programs and deta must also be decided upon. The first part of the physical memory question the hardware to use was easily sloved at the time pc was first designed
memory chips holding 16,384 bytes 16k were the most plentiful and cost affective,they were also the basis most competing  computers.the least expensive and most popular of these stored their bytes in a one dimenstional array,giving 16,384  places to store a single memory bit,other chips might store four bits at a location,half a byte or a nibble at a time ,a minimum of eight chips of these one dimensional chips are required to hold a byte of iformation,because of their one dimensional architecture.
IBM added one more chip to the basic and minimal eight,in the mainframe business data integrity is extremely imporant so large computers use complex schemes for detecting and possibly correcting memory errors.IBM decided to include of form of memory quality in surance in the pc a system that would randomly detect if a memory bit should fail.The simplest possible detection scheme involves adding up all the bits in the byte then adding in a special parity bit  to insure the total is  always even,if one bit changes,the total comes out odd and an error must have occurred.The extra parity check bit requires one additional RAM chip consequently the PC was equipped with none memory chips.
With a bit of prescience (the knowledge that most programs wont run with so little memory as 16k IBM provided palces for adding more memory.A total of 27 empty sockets allowed you to plug up to 64 kilobytes of memory into the PC.with an eye to the future ,IBM even mad provisions for installing boards containing extra RAM,allowing the system to be expanded up to 512k at the time more than any program could possibly require.The IBM engineers reserved the other half of the addressing range of the 8088 for special purposes,some locations were used for videos memory others for the permanently recorded programs in ROM that are collectively called the basic input/output system,only a small fraction of this reserved memory  area was actually put to use but IBM made sure it was there should it ever be needed,in fact only about 20k for the BIOS  in mass storage IBM almost indiscriminately exploited the same options other personal computer makers had used,miniature (for the time)7 inch floppy disks were a natural both because of their use in other small computers and because of IBM's experience with their larger cousins 8 inch drives in other IBM products such as its display writer word processor.
again no one at the time foresaw a need for huge amounts of mass storage,so IBM elected to use only one side of the  potentially two sided disks limiting capacity to 160 kilobytes .although puny by today's standards,that capacity was  substantially greater than the 80 to 130 kilobytes  used in other small computers at the time.IBM also hedged its mass  storage bet by including a cassette port as part of the first pc instead of buying a 500$ floppy disk drive,you could use  your tape recorder to remmember programs and data even exchange files with your friends cassette tape is of course slow and in convenient a particularly poor match for the pc,but should hobbyists actually be the major market for the some what  undirected PC the cassette port would undoubtedly find users.
All computers need a programming language and IBM gave the PC basic the beginners all purpose symbolic instruction code  weighting in favor of IBM's including basic its pc was the acceptance of the language in the small computer industry and among hobbyists the small size of the language that made it unable on machines with limited memory and IBM's own experience with basic in the 5100 .another programming language APL(short for a programming language) was also used on the 5100 and in many cases preferred by the users of the computer.how ever basic won out.much to the consternation of compatible makers ever
since IBM stuffed a rudimentary form the basic into the ROM chips(un changeable hardware) of the pc because mass storage  was essentially optional in the first PC's the machines would have been little more than vegetables without an internal  programming language basic was always there waiting for you even if you had no disk drive ready to save and load programs  from cassette tape..

What is "The intel 8088" you know about it?

The intel 8088 on the other hand ,was similar enough to the z80 that software could be easly converted to run on it,
at least in the theory moreover,the 8088 differed from the z80 in two significant ways.it had wider internal registers and a greater memory addressing range.the 8088 was truly an 8-bit processor in that information moved in and out of the chip 8 bits at a time and while the z80 could only address 65,536 bytes of memory the 8088 could handle 16 times as much  1,048,576 bytes.potentially the 8088 was a more formidable microprocessor. Even in the early 80's more powerful chips were available ,how ever.for example: The bigger and older brother of 8088 the  8086  for in stance had the same 16 bit internal architecture the same wide addressing range and also used 16 bit  connections with the out side world.the difference potentially made the 8086 twice was the fast 8088 even when operating at the same speed. IBM had one good reason for the foregoing the full 16 bit power of the 8086 however,in the early 80's the price of  mircoprocessor support chips as well as memory was much higher than today using a full 16 bit bus structure would add  substantially to the cost of the computer using it.Going with a 16 bit architecture probably did not make sense to IBM's pc Designers as the marketing move,particularly since the 16 bit internal nature of the 8088 would still allow IBM to advertise the erstwhile 8 bit pc as a 16 bit computer,however power was not a reall issue.Although the 8086 brain would have resulted in a superior machine,the market place placed no demands on performance,after all having a computer was vastly
better than not having one,and in comparison the performance difference between 16 and 8 bit designs was insignificant .and 8 bit design would be easier and faster to implement had no relative market disadvantage and was less costly (a powerfull advantage) The 8088 won out over the 8086.Other chips were out of the running.The motorola 6800,a full 16 bit chip,lost  partly for the same reason as the full 16 bit 8086,and partly because it lacked easy CP/M translatability.The texas  instruments family for microprocessors  lost out for the same reason.as a result the 8088 was chosen,not quite an arbitary or capricious decision,but one that lacked the foresight to see performance arising as a major issue in microcomputers...