Opening and searching text file using DJGPP will add significant overhead to the execution due to mode switching. Also, I found most of substitutions are converting AM font to CM font (I only have cm font at home). Therefore, I also modified the program to convert amxxxx to cmxxxx internally to speed up execution. To choose this option one should recompile the source without defining FONTSUB (i.e., take out -DFONTSUB in the makefile). Finally, the makefile enclosed is compatible with both NDMAKE45 and Borlan?'s MAKE utility.