High Quality Content by WIKIPEDIA articles! The Harvard architecture is a computer architecture with physically separate storage and signal pathways for instructions and data. The term originated from the Harvard Mark I relay-based computer, which stored instructions on punched tape (24 bits wide) and data in electro-mechanical counters. These early machines had limited data storage, entirely contained within the central processing unit, and provided no access to the instruction storage as data, making loading and modifying programs an entirely offline process. Today, most processors implement such separate signal pathways for performance reasons but actually implement a Modified Harvard architecture, so they can support tasks like loading a program from disk storage as data and then executing it.