I am now able to run all immediately important keyfunctions in Pure TI-BASIC, using no input command, other than getkey. This, in theory, allows for one to create input consoles on the graph screen, or have the input only use numbers, etc. etc.
Str0+sub("…50 question marks…-1sin(cos(tan(^?????2,()/?????log(789*?????ln(456-?????123+?????).-",Ans,1→Str0
The hope of this code is that one day, you will be able to preserve Ans with it, and even put this on the graph screen to allow for more lines. Right now, it is probably very unoptimized, and also not as pretty as it could be, but it is functional, and from here, much more can be done.
Just edited the code to allow you to clear the homescreen with the clear command. It's very robust. Also, I wondered whether the If statement without the Then would interpret the DelVarAClrHome as one command or two, so I just added in a Then and End.