All You need to know about a processor.
Functional characteristics of a processorThe processor controls the system bus, and the system bus communicates between, the instrucion memory
the processor and the data memory. The processor performs operations on data by executing program instrucions.
A program changes the contents of main memory by sending single binary words back and forth through the system bus.
Program instructions and data are fetched from the main memory (usually RAM) and the results are written to the main
memory. only one operation happens at a time, so the control signals and the data bus can be shared over over the
whole memory. The processor places a numeric codee on the address bus to specify which location is currently being used,
or addressed. A processor Spends alot of time calculating adresses, fetching addresses from memory along the data bus
and sending addrresses to memory along the address bus. this is just so that usefull data can be fetched or sorted
into memory.in the Von Neumann computer, a large proportion of traffic on the system bus is not useful data but merley the
addresses of the data
Addressable Memory
The processor needs to distinquish the parts of main memory that store individual bytes, so each memory
location has a main memory address, like a house address. it is a unique, numeric code! when a processor needs to select
a main memory location, it puts a unique address corrisponding to this location on the address bus. the processor then
asserts, over the control bus, whether it wishes to read from this location, or write to the location. finally, the
processor uses the data bus to transfer a byte(s) between itself and the addressed memory location. All three components of the system bus, adress bus, control bus and data bus are needed when the processor uses a single memory location. a given memory location gains exclusive access of the system bus at a particular instand, but it must shars access with all the other memory locations at all other times, so the system bus is a shared bus.
Stored Program concept
The Stored Program Concept was proposed by john von neumann and alan turing in seperate publications in 1945:
[.] A Program must be resident in main memory to be executed
[.] Machine code instructions are fetched, one after the other, from main memory in sequence and are execured, one at a time in the processor
The computer instructions are represented by numbers called machine code intructions and are sorted the same way as data. thus a bit pattern such as 01000110 might represent 46 or the letter F as data, but if could also be used to tell the processor to perform and addition, thus a single memory location holds value which can be interpreted as data or instructions by the processor in a von neumann computer.
