For all DOS-based programs: An IBM-compatible computer (XT, AT, 286, 386, 486, Pentium, etc.) using DOS 2.0 or higher. A printer is often useful but not required. DOS programs can also be run on Windows 3.1, 95, 98, 2000, Me, and XP.
For COD, SCG, RAC, and PIN: Windows 3.1 or similar, or Windows 95, 98, or higher. A mouse is recommended. If you have a version of COD before August 2002 and want to use it on Windows 2000 or XP, you will need to download a driver.
A hard disk is required for Codes on Disk, and recommended for all other programs. COD requires about 5 meg of space. RAC uses about 3.5 meg. The next largest programs are FILL and KBX Europe, each of which requires about 1 meg of space.