old server

Hi,

I have an old Digital Prioris XL Server 590 which I have successfully
used for running TurboCNC, but now I hope to load Window based
controller like Master5. Unfortunately, although there is a CD-ROM
working (able to load Windows 98 CD) but D: resulted in message:
"invalid drive specification"
ditto with e:, f: ..... z:
a: and b: both resulted in reading the sole floppy drive.

How should I go about to get Win98 loaded so I can use Master5?

Thanks in advanced.

Andrew