Also worth a reminder: some Icom ham-radios from the 80s and 90s use a battery-backed RAM to store their operating-system (along with user-saved options/settings).
Battery goes flat after 20 years and your radio becomes a brick. Beware if you see an Icom radio from this era offered for sale at a suspiciously-low price!
There are ways to replace the battery without losing the operating-system - see
http://www.icomcanada.com/techbulletin/tb1/ram_card.htm