Picture 1

Shows the EPROM (Erasable Programmable Read Only Memory) fitted with a
label marked JAF7. EPROM's can be erased by removing the sticker and
exposing the device to strong ultraviolet light. I incorrectly refer to
it as a PROM (Programmable Read Only Memory. Below it is the old leaking
PLL backup battery.
Wikipedia article about
EPROM’s...