Okay, I feel like there is a real break in communication and I'm curious to explore it. If it gets too tedious for you, feel free to ignore me. Going back to

Okay, I feel like there is a real break in communication and I'm curious to explore it. If it gets too tedious for you, feel free to ignore me. Going back to the N = 5 things. Three seem to help, two don't. The helpful ones: * Reading keyboard is reading a register/known address, not loading the keyboard library, allocating a structure and jumping into an OS routine. * Doens't this make make the program smaller? Getting the key entered is just a read instruction. Sure, there maybe things that happen afterwards (as you said) but just getting the key is one instruction i.e. read <some memory spot> * Clear screen is writing zeros to a known address space * Again, instead of doing a number of instructions to clear the screen (I have no idea how many this takes on a modern computer) you just need to write do write 0 <memory location> * Drawing is writing a 1 to a known address space * My understanding is that on modern computers this is a complex operation. But, in this it appears that drawing is again a single operation. In each case, the point @tezza is making is: Hey, all you people who haven't ever used these crazy old machines, these are the types of things that make it easier to create a very small chess program (in terms of size of the program itself, not the resources it uses). All these things that nowadays require a lot of instructions only required a single instruction on this machine. The other two points, I agree, are probably not helpful. Using the keyboard reading as an example, it seems whoever designed this machine said "one way to reduce the size of programs is to make it easy to read keyboard inputs. Lets have the hardeware store that in a known address." Thus, the fact that you can do this does help reduce the size of the program. Am I wrong? Let me know. I've never worked on these machines so I could be completely off base. A friend of mine used to wonder if it would be instructive to learn about programming under these limitations so I'm genuinly curious. Note: I'm not objecting to your points about what reduced the size of the program. I'm just trying to figure out why you think @tezza's points don't help.