CompuServe Thread

I am attempting to modify a printer driver that I wrote for the Epson LQ-800 printer so that it will print graphics in 24-pin mode instead of 8-pin mode as it currently does. However, the render.c ile is giving me a problem. After I assemble the ".asm" files and compile the ".c" files, I invoke the Amiga linker to tie everything together into an executable printer driver. Everything worked fine when I did this with my 8-pin graphics driver. However, I get a message after linking the 24-pin driver object modules together stating "Undefined external reference in render.o". The undefined reference it refers to is "_CD22". Obviously, I need to include some additional file when compiling render.c ….. but which file should I include? I think that I am getting the undefined reference message because of the math I am using in case 1 of render.. The mathematical expression I am using in case 1 of render.c is i = bufptr + (y % 24)/8 + x * 3 + 4. I didn't use the % operand when I wrote the 8-pin graphics driver so this is probably the specific cause of the undefined external reference. How should I compile render.c now that it contains a % operand and is there anything special I should do when linking together the object modules? Thanks in advance, Fred Kohler.