The OS/2 Display Driver Zoo

Summary

I have recently explored (again) the possibility of writing a high-res display driver for virtualized OS/2. But I ran (again) into a dizzying array of possible solutions, each with its own advantages and a good deal of drawbacks. OS/2 display drivers underwent something of a rapid evolution in the 1992-1996 timeframe. The OS/2 Warp 4 DDK comes with no fewer than four significantly different display driver code bases, which reflect this evolution. Warning: This article is long! It contains notes from research into the evolution of OS/2 display drivers, DDK sample code, and accompanying documentation. Much of the article is something of a signpost, showing where to find what. OS/2 1.x In the days of OS/2 1.x, things were simple. Display drivers were 16-bit, written in assembler (out of necessity more than anything else), and there was only one driver model. The drivers for OS/2 Presentation manager (PM, code name Winthorn) were circa 1987 cloned from Windows 2.x display drivers, since the inner workings (bitmaps, patterns, brushes, fonts, ROPs, and all that jazz) were very similar. Like Windows drivers, OS/2 display drivers worked by “compiling” (dynamically constructing) code to implement various drawing functions. 800×600, big enough for OS/2 1.1 command prompt window OS/2 1.1 (1988) supported device driver interface (DDI) version 1.0, being the first Presentation Manager release. The interface resembled Windows 2.x and was just as ugly. In OS/2 1.x, the Presentation Manager shell (PMSHELL.EXE) directly linked against the display driver, which had to be named DISPLAY.DLL–much like in Windows 3.x and earlier the display driver had to be called DISPLAY.DRV. The 1989 release of OS/2 1.2 looked much easier on the eyes than 1.1 and visually resembled the not-yet-released Windows 3.0. The DDI was upgraded to version 1.2. The newer DDI supported color icons and cursors (OS/2 1.1 was limited to monochrome icons), and the driver needed to supply lots more icon and bitmap res...