Updated BASIC readme file (ghaerr#2195)

* Improved descriptions

* Update README.md

* Update README.md

* Update README.md

elkscmd/basic/README.md

@@ -49,17 +49,17 @@ DIM variable(n1,n2...)
 READ var
 DATA NumberOrString [,NumberOrString...]
 RESTORE [lineNumber]
-CLS
+CLS removes all text and graphics
 PAUSE milliseconds
 POSITION x,y sets the cursor
-NEW
+NEW clears the current program from memory
 LIST [start],[end] e.g. LIST or LIST 10,100
 RUN [lineNumber]
 LOAD "filename" loads filename.bas
 SAVE "filename" saves filename.bas
 SAVE+ "filename" saves filename.bas, sets auto-run on load
 DELETE "filename" deletes filename.bas
-DIR
+DIR list all *.bas files in current directory
 MODE number (set graphics mode, e.g MODE 1 to use PLOT/DRAW/CIRCLE)
 COLOR fg,bg
 PLOT x,y
@@ -97,7 +97,7 @@ CODE(string) e.g. CODE(" ") -> 32
 STR$(number) e.g. STR$(2) -> "2"
 LEFT$(string,n)
 RIGHT$(string,n)
-MID$(string,start,n)
+MID$(string,start,n) extracts a substring from a given string
 COS(x) cosine
 SIN(x) sine
 TAN(x) tangent
@@ -110,17 +110,17 @@ POW(x,y) e.g. POW(2,0.5) -> 1.414 square root of 2
 HEX$(number) e.g. HEX$(25923) -> "6543"
 PEEK(offset,segment) Memory read byte from `segment:offset`
 
-Architecture-specific
+Architecture-specific:
 PINREAD(pin)
 ANALOGRD(pin) - not implemented
 
-Not implemented
-x^y x to the y power - use POW(x,y)
-SQR(number) square root, use POW(number,0.5)
-SGN(number) sign, use IF number < 0 etc
+Not implemented, but alternatives exist:
+x^y x to the y power, use POW(x,y) instead
+SQR(number) square root, use POW(number,0.5) instead
+SGN(number) get sign, use IF number < 0 etc instead
 
-Not yet implemented
-SCREEN$(line,col)
-ATTR(line,col)
-POINT(x,y)
+Not yet implemented:
+SCREEN$(line,col) - retrieves the ASCII code of the character displayed at (line,col)
+ATTR(line,col) -  returns the attribute byte for this screen position. The byte contains information about the color attributes of the pixel block at (line,col)
+POINT(x,y) - checks whether the pixel at screen coordinates (x, y) is ON or OFF
 ```