Development Tools
The Prospero DOS Extender Kit allows Prospero Pascal and Fortran programs to break through the 640K memory limit imposed by DOS. When used in conjunction with any of the supported DOS extenders, it allows the program access to all the available memory. Version 2.1 of the Kit supports DPMI, Windows 3, 286|DOS-Extender, DOS/16M and OS/286.
All 80286 machines and above support two modes of operation: real mode and protected mode. Real mode is compatible with the 8086 and is the mode used by DOS. Real mode programs are limited to 640K. Protected mode programs do not suffer from this limit, and can gain access to all the available memory in the machine. But a program running in protected mode still needs access to the facilities of DOS: a DOS extender acts as an intermediary between the protected mode program and the real mode of DOS.
A number of DOS extenders are available, each with its own facilities and programming requirements. A standard called DPMI (DOS Protected Mode Interface) has been developed, but has yet to be adopted by all DOS extenders. The Prospero DOS Extender kit provides support for DPMI as well as several other popular extenders, the relative merits of which are discussed overleaf.
The purpose of the Kit is to enable the programmer to gain the advantages of extender technology with the minimum disruption. Most existing programs can be converted simply by relinking. Programs with larger code or data requirements can be generated in the same way. Execution of the programs is straightforward; for many of the extenders they may be run from the command line in the normal DOS manner.
The Prospero DOS Extender kit includes a new linker capable of generating protected mode programs for each of the environments. For each extender, either complete new libraries or extra modules to be used with the standard libraries are supplied. Model batch files are also given showing how to link programs. Full documentation is provided, including advice on programming in protected mode.
DPMI is not itself an extender, but rather a definition of an interface. The DOS extender kit produces stand-alone Pascal or Fortran executable programs that will run under any DPMI implementation (version 0.9 or 1.0). Graphics support is provided, including direct screen writes. A special version of Probe is also supplied to allow debugging of programs in this environment. A number of DPMI extender implementations are available. The most notable is Windows 3 running on an 80386, not using the windows environment, but the DOS command shell provided within Windows.
Besides being a windowing environment, Microsoft Windows 3 is widely available and can serve as a DOS extender for 80286 machines and above. The special Pascal and Fortran libraries provide each program with a dedicated window for standard input and output. All the normal file operations that write to or read from the console are redirected to this window, without the need to modify any source code. Most of the Prospero extensions are available apart from graphics support.
The Phar Lap 286|DOS extender provides an extended environment for 80286 machines and above. Nearly all Prospero extensions are supported, including graphics with direct screen writes. The 286|DOS-Extender provides a wide range of facilities, many of which can be directly accessed from Pascal, and it can also run OS/2 programs. It is possible to bind in the extender with the developed program to produce a completely self-contained executable. With the appropriate extender licence, self-contained programs may be shipped to users, who do not need an extender themselves.
The DOS/16M extender from Rational Systems has included DPMI since version 3.9. The special components here are intended for users of earlier versions (3.6 to 3.8); most Prospero language extensions are supported, including graphics with direct screen writes.
The OS/286 extender from Ergo now includes DPMI. The special components here are directed to pre-DPMI implementations including 2.0.x. Most Prospero extensions are supported, but the graphics do not utilise direct screen writes.
OS/2 is not itself a DOS extender, but rather a complete protected mode operating system. Prospero Pascal and Prospero Fortran for OS/2 provide development environments, running under OS/2 and allowing OS/2 or DOS executables to be generated. Object files are interchangeable between OS/2 and DOS, and may alternatively be linked to form executables to run under DOS extenders. The OS/2 compilers may also be run under the Phar Lap extender.
Requirements:
To develop protected mode programs you will
need:
Pricing: The Prospero DOS Extender Kit is available from Prospero Software for 120 pounds (excluding VAT & delivery); contact distributors for local pricing.
For further information, contact:
Prospero Development Software Ltd
London SW15 6EP
England
Prospero@ProsperoSoftware.com
Grey Matter
Prigg Meadow
Ashburton
Devon TQ13 7DF
England
Email maildesk@greymatter.co.uk
System Science
1 Bradley's Close
White Lion Street
London N1 9PN
England
EDV-Beratung Friedrich Pluennecke
Hinterm Dorfe 21
D-38268 Lengede
Germany
fp@pluennecke.de
Lifeboat Inc.
3-6
Kanda-Nishikicho
Chiyoda-Ku
Tokyo 101
Japan
sales@lifeboat.co.jp
Prospero is a registered trademark, and Prospero Pascal and Prospero Fortran are trademarks of Prospero Software Ltd; MS-DOS, Windows and Microsoft are trademarks of Microsoft Corp.; 286|DOS-Extender is a trademark of Phar Lap Software Inc.; DOS/16M is a trademark of Rational Systems Inc.; and OS/286 is a trademark of Ergo Computing Inc. OS/2 and Warp are trademarks of International Business Machines Corp.
Details correct as of Jan 1992.
Prospero Software has a policy of continuous product improvement and reserves the
right to alter specifications and prices without notice.
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