Hello I'm in graduate school and we have an old computer. I'd like to know more about it. Phoenix 80486 ROM BIOS Plus Version 4.03 640 KB Base Memory; 7168 KB Extended memory. 2 questions: 1. Whats the difference between base memory and extended memory? 2. I get 2 error messages when i boot that says "No boot device available" and "Hard disk 1: not installed." Does this mean i need to reinstall the OS? I'm new at the lab so i don't know exaclty, but i suspect it runs on windows 3.x. Would it be possible to install a version of windows 95? Thank you in advance.

Base (or conventional) memory is the old limitation of 640K - you can read more here. Extended memory is everything over 1 Mb - what's inbetween is (in a manner of speaking) used as the high memory area (HMA) and can be mapped for Upper Memory Blocks (UMB). No boot device available means that the system can't find find anything to boot from - in this case, it can't find a hard drive, although you should be able to boot from a floppy. You need to enter CMOS setup and see if the hard drive can be found by the BIOS - you may be able to select 'autodetect' but this was not necessarily a standard feature on machines of that vintage. If that's the case (assuming that there is a hard drive) then you would need to enter the drive specs manually. It's also possible (or even likely) that the actual CMOS battery is weak or dead, so the settings will not 'stick'. The OS necessary to run Win3xx is DOS - that version of Windows was just a GUI (shell) - but you can't install anything unless the hard drive is recognized. Yes, you should be able to install Win95 on this machine once the hardware is in order - check out the minimum requirements. More ram and a large hard drive would improve performance though.

I later realized that my description of HMA given above was incorrect. If for no other reason than posterity's sake: HMA "The first 64 kilobytes (minus 16 byte) of the extended memory on an IBM PC." ... there, I feel better now