This laptop originally had Windows NT 4.0 with multiboot using Boot.ini to DOS, Win3.1 and Windows 98. Later the NT was updates to Windows 2000.

It kept losing time, date and BIOS settings.

Eventually it didn’t do anything.

Difficult to find any information as Dell stupidly named a much later unrelated model as an Inspiron 15 7500.

A Dell person on a Forum suggested it has no “CMOS Battery”. What they really mean is that it’s not user replaceable. It’s a tiny 2 mm by 12.5mm vertically mounted rechargeable lithium cell soldered to the motherboard. It’s just between the rear dock connector and the dual slot PCMCIA holder. You have to remove the keyboard to get to four screws that hold on the rear plastic panel. You then have to remove the PCMCIA holder and then the sound card.

You can’t use a regular coin cell directly and replacing the Panasonic VL1220 seems a bad idea. So I can either use 2 x NiMH AAA cells, if there is space, or maybe a Schottky diode and coin cell, or a larger replaceable rechargeable coin cell (used in some solar charged torches).

This may not repair it (soldering in wires with polarity correct is challenging) and reassembly is tricky.  However I’ve seen plenty of 486 and PIII desktops that had blank video when CMOS battery was flat. Some have the cell inside the clock-RAM module, but I’ve cut away case at two places and added a CR2032 holder to fix those.

I may try a repair some rainy day.

Why bother with VMs?

With Oracle Virtual box you only get file share and copy/paste with XP or later. Not with Win98 or Windows 2000. Also even for XP the Direct 3D now fails on later Virtual Box, due to security.

Secondly some DOS and Windows 3.x and Windows 9x programs read specially crafted parts of the CD directly. This was to stop copied CDs working and piracy. Doesn’t stop “real” criminals. However it means the programs don’t run in a VM or even good emulators.

Update:
I found a working 486 desktop with DOS (2G HDD?) and scrapped a PIII desktop.