National Trade Data Bank (NTDB): Washington, D.C.: U.S. Department of Commerce. 2 disks. $35.00. Annual subscriptions for $360.00. System requirements: any IBM-compatible PC, XT, AT, or PS/2 with at least 640 kilobytes of memory, an ISO 9660 CD-ROM reader, and Microsoft CD-ROM extensions (version 2.0 or higher). The software has the option of using a color monitor (CGA, EGA, or VGA), and mouse.