MICRO-C: Using a RAMdrive to speed up compilation.

The MICRO-C command co-ordinator (CCxx) runs the separate phases of the
compiler (MCP, MCCxx MCOxx, MACRO, SLINK, ASMxx), and uses temporary files
to pass the output from one phase as the input of the next phase. By
default, the temporary files are written in the current directory.

When compiling from a physical disk drive, the system must constantly seek
back and forth between the input file, and the output file. This slows the
compiler down. A significant performance gain can be realized by placing the
temporary files on a RAMdisk, where the seek time is essentially 0 (there
is no physical disk head).

If you do not already have a RAMdisk on your system, you can define one
by adding the following line(s) to your CONFIG.SYS file:

For DOS 4.0 and earlier:
    DEVICE=C:\DOS\VDISK.SYS 256 /E

For DOS 5.0 and later:
    DEVICE=C:\DOS\HIMEM.SYS
    DEVICE=C:\DOS\RAMDRIVE 256 /E

Notes:
 1- The indicated RAMdrive size of 256k is adaquate for most users
    of the compiler. If you get disk full messages, or errors writing
    to output files, try increasing the size of the RAMdrive.

 2- The '/E' option causes the RAMdisk to be allocated in extended
    memory (above 1mb). If you have 1mb or less, or for some other
    reason do not want the RAMdisk allocated in extended memory,
    you may leave the '/E' off, and the drive will be allocated in
    conventional memory. If you are not using extended memory with
    DOS 5.0 or later, you may also omit the DEVICE=HIMEM.SYS line.

 3- After the disk size (256 in above examples), you can specify the
    RAMdrive sector size, and number of root directory entries. Refer
    to your DOS manual for details.

 4- Replace 'C:\DOS' in the above examples with the location of the device
    drivers. If you are running WINDOWS, you should use device drivers from
    the windows directory.

Once you have defined a RAMdisk, you must inform MICRO-C that it can place its
temporary files there. This is accomplished by setting the environment variable
MCTMP to a string pointing to that drive:

  eg:    SET MCTMP=D:\

This command should be added to your AUTOEXEC.BAT file if you wish to always
place your temporary files on the RAMdrive.

Note that MCTMP is a PREFIX, and should end with a trailing '\' if you are
intending to use it as a directory pointer. Also be sure to change the 'D:'
in the above example to the correct drive letter of your RAMdisk if necessary.

It is common practice to place a '$' at the end of the MCTMP prefix, so that
temporary files generated by the compiler can be easily identified:

  eg:   SET MDTMP=D:\$

This causes all temporary files created in D:\ to begin with the '$'
character.
