Final answer:
A digit string F840 2001hex represents a D-type ARM instruction in computer architecture.
Step-by-step explanation:
A digit string F840 2001hex represents a D-type ARM instruction in computer architecture.
ARM is a reduced instruction set computing (RISC) architecture used in mobile devices, such as smartphones and tablets. D-type instructions are data-processing instructions that operate on multiple data registers and can perform arithmetic, logical, and bit manipulation operations.
In this case, the digit string F840 2001hex is a hexadecimal representation of a specific D-type ARM instruction, which would require further analysis to determine its specific operation and function.