If we are talking a Windows 98 installation here is a set of instructions I made for a less than computer literate buddy of mine to follow.
Step 1 – Make sure your cd-rom will be readable in DOS
-Put Win 98 cd in cd-rom drive
-Put Win 98 Boot Disk in Floppy Drive.
-Restart computer
-Select Option 1 start computer with cd-rom support
-Most bios versions will create a Ramdrive to load the diagnostic tools of the boot disk if yours does this then your cd-rom drive letter will be bumped up one letter from D: to E: most usually unless you have multiple HD’s or Partitions.
-Finding the appropriate drive letter for your cd-rom can usually be done by looking at the last line before you get your DOS A:> prompt it should read MSCDEX etc etc Drive E= etc etc if that is the case Drive E is your cd-rom
-Once you have determined the correct drive letter for your cd-rom type that drive letter at the a prompt i.e. A:\>E: then hit enter, this should change the A prompt to an E prompt. Type DIR at the E prompt this will then list the contents of the drive if one of the folders is WIN98 you are seeing the cd and can proceed to step 2 if you don not see this folder or get an error you are either in the wrong drive letter or your cd-rom isn’t getting the needed DOS driver from the boot disk (fairly rare).
Step 2 – Formatting the Hard Drive
-Change the E: prompt to C: if you have multiple HD’s you may want to type DIR and verify you are about to format the correct drive before toasting all your data
-Once certain you have the correct drive at the C: prompt type format C:\ assuming it is C you want formatted. Command will look like C:\>format C:
-You will get ominous message about losing all your data make your choice as it’s the point of no return after you hit yes J
-Drive will do some diagnostics then format the drive
-You will get asked to assign a drive label, none is required but you can name it if you wish
Step 3 – Re-installing Windows 98
-at the C prompt type mkdir C:\WIN98
-this will have created a directory on your C drive called WIN98
-at the C prompt type D: to switch to the cd-rom drive, it may or may not have switched back to being the D drive after the format if you go to D and type DIR and do not see the WIN98 folder then check drive E
-Once you find the appropriate drive for the cd you want to switch to the WIN98 directory do this by typing cd WIN98 the prompt should now be D:\WIN98> assuming we are in drive D now you need to copy the necessary files from the cd to the Hard Drive which will aid installation to do this type copy *.* C:\WIN98 i.e. D:\WIN98>copy *.* C:\WIN98
-You should see all the files copying to your C drive once that is complete you are ready to begin installation
-Switch back to the C drive and then into the WIN98 directory
-Type setup.exe and follow the prompts to install
-Once completed you can delete the folder WIN98 in your C drive if you need the space if not it’s handy to keep on as then anytime Windows needs a file where you would usually have to find and put in the cd you can just direct it to C:\WIN98 and you won’t need the cd.
In step 3 you can simply run setup from the cd but I like to copy the files over and run it from the HD as I have had windows stop recognizing the cd-rom during installation in the past.
I hope this helps and if any of the many folks on here with way more pc skills than I have notice any problems with the directions please correct them!