Typically, concording programs that run on hard disks require anywhere from 2.5 to 8.5 megabytes of disk space, depending on the method of indexing used, the number of active texts and translations and the sophistication of the search features supported. The amount of memory needed varies from program to program. One megabyte on a Macintosh and 512K on IBM PC-compatibles are typical requirements. Most of the IBM-compatible programs I have used run on any machine from an XT-class up, including PS/2 models. The Macintosh programs I have used can be run on any machine from a Macintosh Plus up. The faster and more powerful the computer, and the faster the hard disk, the faster the concording programs will perform.