Ok, fair. Mac resources, including CODE resources, could be modified by the running program and unless marked as read-only were saved to disk by the relevant Manager before unloading. Photoshop was noted for its unusual use of disk, which was said to work like a virtual memory system.
Due to lack of protected memory, a few programs, especially on the earliest machines, with the least memory, 'abused' the display buffer by using it as RAM. Of course, this corrupted the screen, but it would all just be drawn again as soon as the program yielded time to the OS. Back then, only one user program could be running at a time, and it mostly had the screen to itself, so why not use it to copy floppies with less disc swapping?
