XP4 is based on the original Sky Commander DSC design but with the following important hardware upgrades:

At this time the XP4 Boot-Flash Utility is available for download. With it you will be able to upgrade to the most recent version (5.03 SP00). With this version you will be able to select from a number of astronomical catalogs.

XP4 supports the following astronomical catalogs, collectively over 30,000 objects:

* Well written Observing Guides for the Hickson and Abell Planetary Nebulae, including finder charts, sketch and observing notes are available at www.faintfuzzies.com. The Arp Observer's Guide is due for release in mid-2007.