HP 19B teardown part 1

[brouhaha]

Someone here in the forum was kind enough to give me a broken HP 19B. I've taken apart first-generation clamshells (18C, 28C) before, and their construction is documented in HP Journal articles, but I haven't previously seen the innards of second-generation clamsheels (19B, 19BII, 28S) which use the Lewis (1LR2) chips with industry-standard bytewide SRAM.

I carefully peeled away the labels and Richard Ottosen drilled out the heat stakes using a Dremel drill press and a drill bit which he put in a small metal tube to alleviate problems with flexibility of the bit:

https://www.flickr.com/photos/22368471@N...193666469/

Once the case was opened, one side of the PCB was revealed, showing one normal SOIC static RAM, and the back side of the dice of two custom HP "Lewis" chips (1LR2), which are attached to the other side of the board using Tape Automated Bonding (TAB), similar to some but not all Pioneer models:

https://www.flickr.com/photos/22368471@N...193126379/

It is the other side of the Lewis dice that is of interest, so I'll have to remove the LCD display, held in place by a metal frame with folded tabs. Even though the bottom of the dice are bare, the top are most likely covered in epoxy, so decapsulation in fuming nitric acid will still be necessary.