OS/2 Protected Mode Restrictions for Basic 6.0 to 7.1 (28442)

SUMMARY

The following is a list of restrictions under MS OS/2 protected mode for Microsoft Basic Compiler versions 6.0 and 6.0b and Microsoft Basic Professional Development System (PDS) versions 7.0 and 7.1:

1. Programs using statements that refer directly to addresses in the machine's physical memory may need modification when run in protected mode (for example, CALL ABSOLUTE, DEF SEG, PEEK, POKE, BLOAD, BSAVE, VARPTR, and VARSEG).
2. Graphics are limited to SCREEN 1 and 2. EGA and VGA graphics are not supported in protected mode.
3. Only one screen page is supported in SCREEN 0, SCREEN 1, and SCREEN 2. In other words, the active page and visible page arguments of the SCREEN 0 statement are not supported under OS/2 protected mode. (SCREEN 1 and 2 only support one screen page in MS-DOS and OS/2.)
4. Except for BEEP, no sound is supported. SOUND or PLAY statements are not allowed in protected mode. As a workaround, you can make an OS/2 CALL to create a sound with a specified frequency and duration.
5. Light pens and joysticks are not allowed in protected mode.
6. CALL INT86, INT86OLD, INT86X, INTERRUPT, and INTERRUPTX are not available in protected mode.
7. COLOR is ignored in SCREEN 1 in protected mode.
8. INP and OUT are not available in protected mode.
9. IOCTL and IOCTL$ are not available in protected mode.
10. PALETTE [USING] is not available in protected mode.
11. WAIT is not available in protected mode.
12. If a program in real mode is using the serial communications port (COM1 or COM2), then you cannot use that port in protected mode at the same time. This is an OS/2 restriction. The reverse is also true: if a program in protected mode is using the communications port (COM1 or COM2), then you cannot use that port in real mode at the same time.