How to upgrade a 375 or 345 to a 380.

You need three new parts. An 040, a new oscillator and new ROMs. Buy an 040 and decide what speed you want to run it at. The HP can handle 25 or 33 MHz. See what the max speed on the 040 is. You can probably run the 040 at a higher speed than the max speed printed on it, but then again, you could burn it up. The oscillator is twice the speed that you run the 040 at, so it's 50 or 66 MHz. To get the ROM, call HP at 800 227-8164 and order part #1818-5062. I paid something like $23.

Then pull the "L" shaped daughter board. It plugs into the 04,Vot, so put the 040 in there. (Make sure you align it correctly.) Right next to the 040 socket is an empty dip socket for the oscillator. When the daughter board is in, the oscillator is on it. So now you need to add one on the mother board. Then replace the ROMs and away you go.