I recently got an IBM PS/1 for free from a friend. It has PC Dos 4.0 which is rare and I actually really like the OS so far. If I could get a sound blaster for it then it would be a good Dos gaming PC, the only problem is that the A drive is not working. No matter what disk I put in it it says "unformatted or bad disk". I know that this line if IBM PCs are fairly hard to upgrade and are fairly proprietary for hardware and what not. It does have the expansion on the bottom of the unit with included B drive. Is there a way to replace the A drive easily or is it specifically built for this PC? Can it be repaired? Can a CD rom drive be used with this PC?

Thanks in advance.