Elements of Programming

Abstract

When we left our ellfin and the damsels at the end of chapter 2 they had just updated the stock figures for Ale. At that time we had not discussed binary numbers and our computer was, implicitly at any rate, a decimal machine. Nor had we considered the constraints that might be imposed by word length. For example, it had been assumed that the instruction and its operand could all be fitted into one storage location, but we now know that this is not possible. Also no limit had been set on the quantity of stock that the dealer might hold. In fact the starting stock of Ale was 909, a figure well in excess of the 255 limit imposed by an 8-bit word.