However PLTL and POINT seem to be BASIC commands
i found a source file of the program
And yes, BASIC does have some drawing commands built-in, which ones exist depend on the implementation.
http://simh.trailing-edge.com/hp/#Downloads
here are the source files basically
For example in QBasic you have CIRCLE, LINE, ... https://en.wikibooks.org/wiki/QBasic/Appendix
Also other languages you might be interested is Logo, where you give commands to a "turtle" such as "move 5 pixels forward", "rotate by 45 deg", etc. and the turtle traces a line while moving, and you try to make the turtle draw interesting patterns: https://en.wikipedia.org/wiki/Logo_(programming_language)
i assume the commands i sent are working by some inbuilt algorithm
what i want to achieve is this

Come back in 10 years!
That looks quite sophisticated but it does look like a turtle tracing thousand lines here and there, doesn't it 🙃
Again, there are a lot of languages/libraries for doing turtle graphics like in Logo