Applesoft: Mixing DOS and High-Res

DOS uses two memory locations, $26 and $27, which are also used by Applesoft's High-Res routines during the HPLOT TO X,Y statement. DOS commands mixed in with HPLOT TO X,Y statements prevent the X,Y from plotting properly.
To enable mixing DOS with High-Res, you must save and restore the pointer. Statments 25 and 35, in the second program, demonstrate how to maintain the pointer values.

This will not work:

10 D$ = CHR$(4)
20 HPLOT 1,2
30 PRINT D$;"CATALOG"
40 HPLOT TO 33,44

This does work:

10 D$ = CHR$(4)
20 HPLOT 1,2
25 A = PEEK(38): B = PEEK(39)
30 PRINT D$;"CATALOG"
35 POKE 38,A: POKE 39,B
40 HPLOT TO 33,44
Published Date: Feb 18, 2012