Arrays are not special. They are merely sections of memory that are treated by programmers as if they formed one entity. Computers like the CSC-1 do not even "know" that there is such a thing as an array! All that the primitive computer knows is that the machine language program forces it to access memory elements in this order. If a buggy program causes the program to go through its loop once too many times, the incorrect sum will result because a value beyond the end of the array will be added in. Worse, a program that changes elements of an array by rewriting them will clobber data that exists in memory locations beyond the "end" (highest address) of the array. These kinds of bugs are way too common and are the cause of lots of operating systems bugs and crashes.