Re: Ada 95 for DOS

["Randy Brukardt" <randy@rrsoftware.com>]

Henrik Quintel wrote in message
<77864ec9f45765f2740ceac645451f33.86200@mygate.mailgate.org>...
>Hi,
>I am looking for a pure DOS Ada compiler. At the moment I work with
>GNAT 3.13p NT and with GNAT 3.10 for DOS. But both are 32-bit Compiler.
>GNAT 3.10 depends on DJGPP. So it is a 32-Bit Compiler.
>
>My problem is that I want to handle pointers to locate several
positions
>in a DOS-BOX under Windows ME. The two compilers, mentioned above fail.


Janus/Ada 95 is (still) available for MS-DOS. It also uses a DOS
extender (Ergo is included, Pharlap's extender also works if you can
find one somewhere).

There is a package for converting real-mode addresses to protected-mode
addresses you can use in your program, which would allow you to access
any memory in the lower 1 megabyte. (There is no way for a program to
access specific memory above the first megabyte without convincing the
operating system to give it to you, which takes you out of the realm of
DOS.)

    procedure Paragraph_to_Protected_Address (Para : in System.Word;
        Addr : out System.Address);
        -- Sets Addr to a protected mode address for the real mode
paragraph Para.
        -- The address can access at least 64K, unless it is at the top
        -- of the conventional memory area.
        -- Raises MEMORY_ERROR if an error occurs.

This routine uses facilities provided by the DOS Extender.

            Randy Brukardt
            R.R. Software, Inc.
            www.rrsoftware.com