Microprocessor
Microprocessor is chip with a memory which can store lists of coded instructions.
They are classified according to:
1) clock speed which determines in megahertz
1) clock speed which determines in megahertz
2) How many instruction per second they can execute
3) The number of bits processed in a single instruction.
Furthermore they can be classified according to architecture that is :
Risc (reduce instruction set computer )
Cisc (complex instruction set computer )
Cisc (complex instruction set computer )
A microprocessor consists of the ALU which can do an arithmetic calculations and makes logical decisions and CU which provides timing instructions and synchronization signals for all other units. Every data and instruction is an electric signals carried by the bus , the electronic circuits uses only two type of signals that is analogue and digital
Analogue signal vary continuously in voltage or current corresponding to the input information, these fluctuating can represent changes in light ,sound , pressure and an analogue circuits work by measuring these changes
By contrast ….
Digital Signal can have two values 0 and the code used by the digital signal is called binary code , and a digital circuits process information by simply counting or comparing signals.Every data is a particular combination of numbers ,every single number is called bit
Logic Circuits in the CPU manipulate data according to instructions. The bits go through a sequence of switches that changes them in some way The switches can also be used to compare two bits in order to generate a particular output based on Boolean algebra in this case the digit 0 represent false and the digit 1 represent true .
Control circuit directs and coordinates the work of all other parts of the system according to instructions stored in the memory , they organize the movement of the bits through the system , the bits are moved by an oscillator called clock which generate pulses
Memory circuits store bits temporarily or permanently
These memory are:
Rom (which stands for read only memory) . in this memory can be neither erased nor added to .it is a type of non volatile memory, that is the data is stored when the power is off ,and normally the rom contains instructions and programs for the operating system.
Rom (which stands for read only memory) . in this memory can be neither erased nor added to .it is a type of non volatile memory, that is the data is stored when the power is off ,and normally the rom contains instructions and programs for the operating system.
Ram (which stands for Random access memory ). In this memory can be either erased . . or added to. This memory is used to store information for short periods, because it is . volatile that is the data is stored only when the power is on because when the power . . is off the data is lost
Program counter (PC) is one the main registers of the cpu. The cpu must have some means of determing which instruction is the next one to be executed . The PC fulfills this role before a program can be executed the starting address, must be loaded into the PC the continents of the PC are then used as an address to fetch the first instructions from memory. The PC is automatically updated so that it always contains the address of the next instruction to be executed, and this process is usually a simple increment of the PC by one.
The accumulator (AC) functions as a working area for all computations performed by the ALU. For example, before an addition is performed, one of the operands is temporarily placed in the AC. The second operand is then retrieved from memory and is added to the contents of the AC the resulting sum appears in the AC destroying the original contents of the AC. Some instructions, such as "Clear Accumulator" or "Complement Accumulator", operate directly on the contents of the AC. Some central processors may have more than one accumulator. In other processors the functions normally provided by the AC are handled by general purpose registers (GPRs).
