Welcome!
The 2500AD assembler uses a linker to convert the .OBJ file to .HEX. When I used it in the late 1980's, it was another man I was working with who got the linker going (after some calls to 2500AD, a process which was not without some consternation), and I just used his batch file directly and later as a template to make minor mods to. It went like this:
Code:
REM **** Batch file to assemble and link the 65C02 code ****
REM **** Input file name: M.ASM
C:\<directory>\X6502 M
C:\<directory>\LINK -c M -l0 -l0
where "<directory>" gets replaced with wherever you have the 2500AD software. Our "M.ASM" source code and output files were in the same directory where this batch file was.