I have compaq p1,booable from FDD.I formatted it dos mood by command format c:/s.Now it boots,but when I insert win98 cd it does not know cd and sys invalid drive. I tried all drive letter.

http://www.bootdisk.com/

Try this site to download another bootdisk, you need to load the drivers for the CD rom drive on booting. The win98 bootdisk should give you the option to choose whether to load the cd rom drivers or not.