## Display Device Driver Reference for OS/2

[prev][next][parent][TOC]

### .PMI Language Constructs only

Full use of the PMI language hides the implementation of the I/O and MMIO access on a particular hardware and operating system platform from the vendor creating the PMI file. This method provides good portability and code reuse. The initial cost in creating the SVGADATA.PMI file is mainly in rewriting the existing source into the PMI sequences.

Another benefit of this implementation is tighter execution control. Since the VIDEOPMI would be totally data-driven, the chances for memory violations and other execution hazards are minimized.

This implementation should not be used for timing-sensitive hardware, since the interpretation of PMI sequences creates an execution overhead that cannot be fine-tuned at the current time.

Note: SVGADATA.PMI files created internally by IBM are written either in full PMI language or in a mixture of PMI language and imported functions to cover as many chip sets as possible.