The CSC-1 computer suffers from a persistent problem in Computer Science -- it works well for what it does but it doesn't scale up. That is, when it comes time to expand it (notice the word when instead of if), the underlying structure proves too fragile to support changes gracefully.

The CSC-1 has a few registers that are connected in idiosyncratic ways which means that these ways of connection are suitable to the CSC-1's current instruction set but not to any other. If we need to add more instructions, such as multiplication or division, we may need to add more registers and more special pathways. Eventually the complexity of the design will become overwhelming and the designers will be forced to seek a simpler, more regular organization that allows expansion.