ICE, the Interactive Computer Ephemeris, is a computer almanac program for PCs that was developed at the Naval Observatory in the late 1980s. It was essentially a version of the then-popular Floppy Almanac that provided data for extended periods of time. A "beta" version (ICE version 0.5) was tested by a group of users and very few problems were encountered. However, in 1990, for administrative reasons, it was decided not to continue development of the product. The known problems were fixed and a final version of the software (ICE version 0.51) was produced and made available to those users who had tested version 0.5. At that time, those users were notified that further development, distribution, and support of the product by the Naval Observatory would cease.
Therefore, ICE is not now distributed by the U.S. Naval Observatory. The Naval Observatory does not provide technical support for the product, nor does it warrant it in any way. However, because of its history, the program is in the public domain and is available through commercial and other sources. The Naval Observatory does not have any connection to or control over these sources. Apparently ICE versions 0.5 and 0.51 are both available; version 0.51 is the better of the two, although most users will not encounter any differences. If you have obtained ICE version 0.5 from a commercial or other source, and wish to obtain version 0.51, you should contact your source.
If you need an accurate computer-based almanac from the Naval Observatory, you should consider obtaining MICA, the Multiyear Interactive Computer Almanac. MICA has a much more modern user interface than does ICE, and provides a wider range of tabulations. MICA is available for both PCs and Macintosh systems.