This software is now freeware. It was written by me many years ago and may not run satisfactorily on some of today's PCs, even though it follows all of the rules for proper screen access. It is a DOS program but does run quite happily under Windows. If it does not occupy the full screen you may have to press Return while holding down the Alt key. If there are memory problems, make a short-cut and set the memory parameters of the short-cut from Windows.
Because it is freeware, no responsibility can be taken if it causes you problems, however I shall be surprised if there are any other than not running satisfactorily. I have no plans to upgrade this software but still find it very useful.
Download now PC-Planetarium.zip and then unzip using Winzip or similar.