Com A error when booting PC?
You need to get into the
BIOS SETUP, older computers usually the "Del" key or sometimes the first screen tells you which key to hit.
Com=Communications can be a modem error, serial port error, printing port error.
https://support.intergraph.com/itser.../dha022440.pdf
This is a manual I found.
Hit DEL to enter BIOS Setup
Under Peripheral you will see OnBoard Serial Port, if your not using a serial port (say for printer) then disable them.
1. To run Windows 98 you will need drivers and they may be hard to find.
2. If the Windows 98 is the "Full Version" then you cannot just upgrade, you would have to format and install Windows 98 as a clean install.
3. If you have enough space on the drive (A 2nd partition) you could dual boot 95/98.