64 bit processor only works with 64 bits and no less?

Question

Processors

Is it possible to give the processor an input number less than 64 bits?
Or in another way the question is: how does a 64-bit processor work with 32-bit programs, the emulator writes the remaining half with zeros in a vacuum, and still gives it a portion in 64-bit form?

Answer 1

With 32-bit instructions

Answer 2

Technically, a 64-bit processor only executes 64-bit instructions. But some processors have a block for translating commands from 32 bits to 64, which can be enabled programmatically. So, the operating system determines the executable type of the program by the file header, and if the file is in 32-bit addressing, it cocks it to allow using the translation block for this program.
Of course, everything is much more complicated, and to execute 32 programs, you need libraries in 32-bit format, and you need to know how the memory translator works, and address protection blocks, and the process scheduler, and a bunch of other things, such as fetching addresses from memory. But actually, this is not the case.