From: Charles Sandmann Newsgroups: comp.os.msdos.djgpp Subject: Re: Generate real-mode 386 DOS executables? Date: Sun, 05 Jan 2003 21:59:43 CST Organization: Rice University, Houston TX Lines: 31 Message-ID: <3e18ff2f.sandmann@clio.rice.edu> References: NNTP-Posting-Host: clio.rice.edu X-Trace: joe.rice.edu 1041826169 2337 128.42.105.3 (6 Jan 2003 04:09:29 GMT) X-Complaints-To: abuse AT rice DOT edu NNTP-Posting-Date: 6 Jan 2003 04:09:29 GMT X-NewsEditor: ED-1.5.9 To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com > The code is run on a Pentium-based embedded system under MS-DOS v6.22. > I'm considering DJGPP as a replacement for the Turbo C/C++ compiler. Other developers have followed this path - DJGPP images (and CWSDPMI) are in the ROM of some systems. CWSDPMI can use the real mode memory to provide 32-bit addressing; systems with a 386+ processor with at least 512Kb of memory should work. > I'm willing to take the pain of the 16-bit to 32-bit conversion, but I > want the pain to end there. That is, I don't want to have to install > himem.sys to support a protected mode application. HIMEM.SYS is not needed, and you can bind cwsdstub.exe into an image for a single EXE distribution. > The 640KB of DOS address space is enough You will get 32-bit addressing even if you don't need it. Trying to use size overrides in 16-bit mode slow down code. > I really don't need access to extended memory, just 32-bit > code generation from a contemporary C compiler. The DJGPP defaults assume lots of memory (a 512Kb stack default, for example) but you can build images which are memory efficient and work fine on a small memory environment. > So... can I use DJGPP to generate a 32-bit real mode DOS application? Not easily - but it's not clear why you would want this (unless you spend most of the time making BIOS calls).