The IBM/Windows version of PREPRO2012 comes with executable codes, in compressed form. 1) Copy IBMPC.tar.gz to your hard drive. First uncompress and untar - we recommend you use 7-zip, which is available FREE on the internet, or any similar uncompression code that you may have. After installation you should have a single directory named PREPRO12 that contains 42 files; you can then delete IBMPC.tar.gz 2) To VERIFY proper installation, it is recommended that after installation you execute VERIFY.BAT (Be sure to type the entire name, VERIFY.BAT, to avoid a conflict wth the DOS verify command). This is a batch file that will run the codes in sequence. 3) The final two codes will display the calculated cross sections (EVALPLOT), and compare the results you calculated to a standard set of results (COMPLOT). Difference of about 1 % to 2% are acceptable; larger differences indicate an installation problem. If plots are displayed before the batch file (VERIFY.BAT) finished, the entire system has been verified and is ready to use. If you do not obtain plots, there was an ERROR during installation; in this case 4) below. 4) If you have any problems notify the Nuclear Data Section, IAEA, Vienna, Austria. services@iaeand.iaea.or.at