INCDIR for RELEASE V

Hi, there,

I am using C51 with RELEASE V, 1993. It looks like this release doesn't support INCDIR option for C51 compiler, isn't it?

In details,
1. I tried

      c51 HELLO.C INCDIR(inc)
   

in which inc is a subdirectory contains the REG51.H and other header files. The compiler complain that, "Syntax error: "(" unexpected".

2. It does compile successfully when I set C51INV environmental variable to be "inc".


My question is, how to write a Makefile, while not to set the environment variable manually? In specific, adding following two lines in Makefile doesn't work,

  C51INC = /cygdrive/c/myproject/c51_impl/inc
  export
 

many thanks beforehand,
Kan