Upgrading processor on Latitude 120L Laptop?

I doubt it is possible, Pentuim M processors are no longer made and considered old technology. You would have to source second hand

Additionally laptops are built to very tight cooling specs, if you could find a higher spec processor it would generate more heat & your laptop would probably overheat or the fans would be running overtime and the battery life would be less.

The standard BIOS may not recognise the faster processor and a BIOS upgrade (if available) might be needed.

If you have ever dismantled a laptop you would see it is not an easy job to dismantle and you also risk damaging some of the delicate ribbon cables especially the first time round.

For all these reasons your project is a non-starter, sorry

Dell Latitude 120l Specs

There could in ordinary terms be one... In each and every workstation, the RAM modules are constantly at the same time. If there is in ordinary terms one slot, then it in ordinary terms helps one slot. they do no longer placed RAM modules in diverse places on laptops. The tech specs from Dell says there are 2 slots. the 2nd slot may well be below the 1st one. Take out the 1st RAM chip and seek for a slot below. additionally, that's basic to locate the 2nd slot on the backside component of the 1st slot.

Your best bet if your are serious would be to check with a dell certified shop to work on it. Other than that it is likely far cheaper to buy another laptop.