What is computer Architecture?

What is computer Architecture?

Computer is made of several smaller components like CPU, Memory, Input Output Devices, Network interfaces etc. There has to be a standard method to get them all together and make them work every single time they are powered on. That method of organizing them all into one place is called Computer Architecture.

It starts with design of CPU the central part of a computer. The working of CPU and its capabilities are defined in terms on instructions it can execute. The size of data bytes and address bytes It can utilize. These three things make up the Instruction Set of the processor also called as ISA (Instruction Set Architecture).
Based upon types of instructions and their lengths in bytes two types of ISA have exist till now. The RISC type and CISC type.
RISC : Reduced Instruction Set Computers
CISC : Complex Instruction Set Computers
The ISA type is dependent upon the microarchitecture implemented with the processor. In fact both are interdependent.
Once the ISA of the processor is defined and made available to the external world, people who are supposed to use that machine can then code programs to be able to run on that processor.

Next part is Memory handling: how does the memory organization takes place to allow the CPU to make use of full address space for its working independent of the physical constraints related to memory (RAM). This is handled my memory management unit. Currently they implement policies like memory paging and segmentation also called Virtual Memory to map the available RAM to the CPU.

Then comes bus interfaces that deal with I/O devices like Display units, printer etc. Each of them has a different data format requirement. CPU needs a translator in between to allow communication between the devices and CPU. This is handled by device driver units a combination of software and hardware that does the translation of data between CPU and device. Like we have a display adapter that converts digital images generated by CPU into VGA / HDMI signals. Printable pages into serialized data formats for printers and likewise.

All of these together make up computer architecture. Each one of these is a matter of further study for actual practical knowledge. This is just to give you a big picture.