I would like to interface Hp printer to 8051 through parallel port. can anyone suggest how to initialise the printer, and procedure to send data to printer.
The OP for that thread, Henry Liu, has several posts and is trying to get interest in a kit. I don't believe he has actually posted any code yet, but the thread is related to another thread by Volkan Sahn (not sure of spelling) in which the prospect of an open-source project was discussed. So, Henry Liu might be willing to share the code he has.
Inkjet or laser? All HP laser supports PCL language. Current version is PCL6. You can search the web for the standard. And download the technical ref. manual from HP. Not an easy thing to implement completely, but you might get away with partial implementation if you are not going to print complex things.
If you just want to print text, and simple text based graphic, you can use simpler standard, like what DOS used to dump text file to LPT port.