Complex sentence: The PCX format supports simple data compression and was quite common on early DOS and Windows systems, but is nowadays rare, having been largely replaced by formats which support better compression ratios, such as GIF, JPEG and PNG.
Split into simpler sentences: The PCX format supports simple data compression and was quite common on early DOS and Windows systems. But is nowadays rare, having been largely replaced by formats which support better compression ratios, such as GIF, JPEG and PNG.