Interrupt driven I/0 handling Suppose in an architecture, interrupt driven IO is used. And suppose a program is to be loaded from an IO device into the RAM. I have been studying IO mechanisms and I came to know that upon receiving a request to load a program, the processor generates control signals to the IO module and then the data is loaded into the IO module interface buffer. When its done loading, it will generate an interrupt to CPU.

But how does a complete file or program gets transferred to RAM? I mean does the processor issues requests only for a byte/word transfer at a time and the interrupt is raised each time a word gets transferred from io device to module? Or is it something else? Please help me understand.
I modern architectures the peripheral has direct access to the system RAM independent of the CPU and what it is executing. This is called a DMA (direct memory access) transfer.

In other words when the interrupt is raised the entire transfer is already completed and you can read the data transferred.