In cortex m3 processor what is used as a temporary variable for arithmetic operations like multiplication or addition. In 8085 we have accumulator A.similarly what is used for Cortex m3 Also where is the string stored before being transmitted using uart in cortex m3 processor ?
I suggest you spend some time with the documentation from the ARM website. But the ARM chips have many general-purpose registers so not just a single accumulator.
Storing a string? Well - in RAM, FLASH, EEPROM or wherever you decide to store your string. The processor haven't any hardcoded space for storing strings. And there are nothing magic about the UART. You either pick up a character and manually put into the UART transmit register. Or you fill a FIFO with many characters. Or you configure a DMA channel to keep the UART busy. Nothing magic at all.
Have you actually spent some time reading ARM documentation, and the datasheet/user manual for any specific processor?
I know the registers r0-r15.What i wanted to know is that is there any temporary register used for arithmetic operations while performing operations like Add r1,r2 in the AHB or is it done directly. p.s: I'm referring to arm cortex m3 user manual.
All processors have one or more ALU.
But most newer processors do not have any ACC - no dedicated accumulator register hard-coded as one of the inputs and hard-coded as the output.
The proceessor routes the contents from one of several general-purpose registers to the ALU and then routes the result back to one of several general-purpose registers.
And besides the "big" ALU, they can have small ALU with limited capabilities - often used for on-the-fly address computations.