What happens to a program post the machine code state? An assembler/compiler will convert high level code or assembly code to machine instructions. At this stage, the machine instructions is still in the software form and reside in memory. How is this code converted to physical electric signals that can then be processed by the hardware? If there is some kind of interface device, I would like to know how it does the conversion.
From the time your muscles and fingers touch the keys on the keyboard the source code becomes electrical signals. this continues through compiling and execution. There is a book by Petzold called Code, you might find it interesting.