I'd like to think it was 3, just because the design has just enough of a PITA factor that it's just plain easier to pay Honeywell for updates so long as the program exists. But as soon as the program doesn't exist, at the least the hardware isn't a brick.
Another possibility is that they designed it as just a thin brick wall for the consumer, never suspecting or caring if they'd reverse engineer it one day, while making it easy for them to do these updates by mail. By making a system easy for Honeywell to provide mail-in updates, they unwittingly made it easyish to hack 20 years later.
Another possibility is that they designed it as just a thin brick wall for the consumer, never suspecting or caring if they'd reverse engineer it one day, while making it easy for them to do these updates by mail. By making a system easy for Honeywell to provide mail-in updates, they unwittingly made it easyish to hack 20 years later.