The calculator comes with a matching protective shield which slides down over the front; when the calculator is in use, you can slide it over the back. This is a nice touch, as it makes the cover much more difficult to lose.

Flip the device over to access the battery cover.

Using a spudger, pry the release tab down and then pull the battery door up and off the calculator.

Remove:

2 7.2mm Phillips #0 screws

1 15.3mm Phillips #0 screw, and a battery retaining clip.

Insert a spudger into the seam between the two halves of the case, and pry it apart.

Watch out for corrosion in older calculators around the battery terminals -- this is why you should never leave batteries in electronics for extended periods of time.

Opening the two halves of the calculator reveals a foil shield over the rest of the electronics.

Remove four Phillips screws to access the electronics underneath, then pull the shield away.

... And, here's the guts of the thing.

SRM20255LLM10 / F4ZM1938 (32Kbyte SRAM)

LH531GP4 (Mask ROM)

T 84C00AM-8 (Z80 CPU)

Toshiba / TC14L010AF / 1273 9506EAI (ASIC)

Remove the remaining Phillips screws.

The screen and main board will lift out, leaving the membrane keypad in the front case.