HP21 uses same RAM chip as HP25?

[calc-calcs]

Yes I saw your nice video a couple of days ago while searching for information. I like to use an old school solderpult pump and a SP35 Weller iron dialed down to about 25W with a light dimmer and a fine ST7 tip. Very effective with a drop of flux on each IC pin to clear the holes, and then wiggle the pins to make sure they are completely free before pulling the chip.

BTW are the holes fully plated through or do they need to be soldered on both sides? I would expect them to be plated but by the amount of solder on some of the pins at the component side it looks a bit like it was soldered on both.

Alex