OS2-DD	C Character Device Driver Support Package
	for OS/2 1.3 and 2.0.

	Andreas Kaiser,
	Danziger Str. 4
	D-7000 Stuttgart 70
	Germany

	Fido:	2:241/7220.9
	Subnet:	ak@ananke.stgt.sub.org

Legal Notice (I don't write legal stuff in a foreign language, sorry):
----------------------------------------------------------------------

Ich uebernehme keinerlei Gewaehrleistung f�r korrekte Funktion oder
irgendwelche daraus resultierenden Schaeden oder Folgeschaeden. Es
liegt in der Natur von Geraetettreibern, dass dadurch die Integritaet
des Systems verletzt werden kann.

Licence:
--------

You are free to use and modify this source, as long as you make your
source and your device driver available for public according to the
usualy GNU Copyleft license and send me a note for what device your
driver was written.

Files:
------

This driver was developed for Zortech C, but should be usable with
other compilers too.

dd-head.inc	Device driver header.
		Requires some symbol definitions
			DD_ATTRIB	Driver attributes.
			DD_NAME		Device name, 8 characters
					padded with spaces.
		The driver source must provide an ASM file, which
		defines both symbols and includes this file. No more
		contents are required. The generated object file must
		be the object first file in the linker command line,
		since the header must be the first data in the EXE/SYS
		file.

dd-segs.inc	Device driver segment definitions.
macros.inc	Utility macros.

lowlevel.asm	Bottom layer. Contains entry point, C wrappers.
		for most DD helper functions, ...

dd.h		Device driver definitions and declarations.

strategy.c	Strategy routine. Dispatches device driver functions.

ddebug.c	Debugging code for direct video output.

		If you use Zortech C, the function _STI_ddebug is
		automatically called whenever this file is linked
		with the driver (= when debugging code is compiled).

		If you do not use Zortech C, you have to call
		_STI_ddebug as the first statement of DrvInit();

		Set the variable video_address to 0xB8000 to get
		debug output on VGA, the default is 0xB0000 for a
		monochrome chard. Use monochrome whenever possible,
		you might not get init time output for BASEDEVs when
		the output is on VGA.

d2debug.c	Same as ddebug.c but for BASEDEV drivers.

		If you do not use Zortech C, you have to call
		_STI_d2debug as the first statement of DrvInitBase();

def_*.c		Default driver functions, called by strategy()
		unless defined in the device driver source
		(requires linking with /NOE).

demo.def	Sample definition file.

Usage:
------

You should already know about OS/2 device driver programming. The
strategy dispatcher calls functions named DrvInit, DrvRead, ... (see
dd.h) whenever the corresponding function code is received. The default
versions in this library return an "Invalid Function" error indicator.
These functions should return the status word (e.h. "return DONE").

Debugging support required a monochrome card. Debugging is enabled when
compiling with DEBUG=1. For non-ZTC users: Don't output debugging info
before DrvInit or DrvInitBase calls the appropriate _STI_ function.