🚀 go-pugleaf

I tried doing some simple graphics programming recently on somebodies recently
aquired PC clone.  I tried accessing the EGA graphics using the BASIC
commands SCREEN 7 and also 8,9, and 10.  It resulted some type of function call
error.  Accessing CGA graphics via SCREEN 1 and 2 worked OK.  This suggests
that the PC does not have EGA graphics.  But the bill of sale shows that computer
has EGA graphics.  How can I tell for sure?  If EGA is installed, then how
do I get it to work in GWBASIC?  Am I even interpretting the BASIC manual properly?

BTW, when going from screen 0 to screen 1 to screen 0, the display changes from
80 columns to 40 columns.  How do change back to 80 columns again?  Is there a
simple command?  When going to screen 0 to screen 2 to screen 0, I do get 80 columns
again, but the characters are cyan on a yellow background.  Using PALETTE 0,0
creates a black background again.  I understand how PALETTE works in screen 1
(and screen 2) I think, but not in the screen 0 text mode.  Please explain how
to get around these difficulties.

One more question:  is there a simple way to get rid of the BASIC function key
descriptions at the bottom of the screen that occurs in the graphics modes?

Please email a response.  I do not regularly read the ibm.pc user group.
Thanks in advance.