Compilation of device drivers.
--------------------------------

    The compiler considerably will facilitate your work at writing drivers.
The compiler itself will create header of the driver and procedure the
STRATEGY and INTERRUPTION. You need only to write the code of processing of
commands.

    What to compile the file of the device driver, it is necessary to add in
the command line a key /SYS. Besides the new instructions have appeared to
the compiler, which operate only with this key. Here they:

   ? sysattribute <value> - this instruction transfers the compiler attribute
the created driver. By default the value 0x2000 is installed.

   ? sysname <text string> - this instruction transfers the compiler a name
the future driver. By default the name "NO_NAME" is assigned. Length of the
name not more than 8 characters.

   ? syscommand <command_0>, <command_1>... <command_n>; - this instruction
is mandatory. Under this instruction the list of names is transferred to the
compiler procedures of processing of commands of the driver. The names are
divided by commas. The list owes to come to an end in character a semicolon.
It is possible to transfer no more than 25 commands. If any command has not
the code of support, in the list it is necessary to write down word NONE.

    By default the compiler for the driver does not create the stack. The
driver can to use the system stack. But, speak, that it has small depth.  If
your procedures actively use the stack and you do not hope on system, that by
the instruction ?stack <value> is possible to force the driver to use by the
stack.

    To your procedures of processing of commands by transmission of handle in
the registers ES:BX will be transferred the address of header of inquiry. The
register DS is equal CS. At return of handle your procedures should save the
register DS. In the register AX should be a return code. Other registers can
be are used arbitrarily.

    The procedure of processing of the command of initialization it is
desirable to have last (to have possibility to give back address space,
borrowed, by this procedure to the operating system). Before this procedure,
if you in other procedures of processing of commands use dynamic procedures,
necessarily there should be an instruction ?setdinproc. The global variables
owe it to be necessary initialised.