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3.9 How to configure your system for DJGPP

Q: How do I configure my system to get optimal performance under DJGPP?

A: That depends on the amount of RAM you have installed in your machine. Below are some guidelines to help you.

  1. If you have 2 MBytes or less RAM installed:

    With this configuration, GCC will run out of free physical RAM and start paging when compiling almost any C program and all C++ programs. If you are serious about DJGPP development, you need to buy more RAM urgently.

  2. If you have 2-4 MBytes of RAM installed:

    With this configuration, GCC will still run out of free physical RAM and start paging when compiling large C programs and most C++ programs. Plan to buy more RAM as soon as you can.

  3. If you have 5-8 MBytes of RAM installed:
  4. If you have more than 8 MBytes of RAM:

Some people disable the delayed-write feature for safety reasons, to avoid losing files due to system crashes. If you are worried about this, you can usually gain performance without sacrificing safety by enabling delayed-write together with an option that causes the cache to flush the write-behind data before the system returns to the DOS prompt. For a SmartDrv disk cache, this is achieved by specifying /N/F switches instead of /X.

Using a memory manager, such as EMM386 or QEMM, is not required (DJGPP will run without it), but highly recommended, since it has several advantages:

If your memory manager is EMM386, I recommend to put the NOEMS NOVCPI parameters on its command line. This will allow you to use UMBs and up to 128MB of physical memory (if you have that much installed). Without these parameters, many versions of EMM386 limit your physical memory to 32MB.

It is generally not recommended to install DJGPP on a networked drive, since this makes it slower, particularly when linking programs. If you do install DJGPP on a networked drive, you should consult your network administrator to configure the network for maximum performance. For Novell networks, a good place to look for advice is the Novell FAQ (search for a file called nov-faq.htm).