18 Low-level DOS/BIOS and Hardware-oriented Programming

This chapter sheds some light on a few aspects of writing DJGPP programs which interact with hardware or use interrupts.

• int86: int86 doesn't always work.
• Pointer segment: How to specify pointers when you call an interrupt.
• Zero SP: How to call real-mode procedures.
• Xfer: Moving data to and from conventional memory.
• Move structs: How to move structs from conventional memory.
• Fat DS: Fast direct access to memory-mapped devices.
• Above 1MB: Interact with memory-mapped devices above 1MB.
• RMCB: How to let DOS/BIOS call your code.
• Hardware interrupts: How to hook HW interrupts from DJGPP.
• _go32 vs __dpmi: Which functions should you use?
• HW Int pitfalls: Does your machine wedge? Here are some reasons.
• Inline Asm: How to write inline assembly with GCC.
• DMA: How to use DMA from DJGPP programs.