microprocessor based fire alarm systems

hi
i am doing a college based project on microprocessor based fire alarm
systems. I am trying to get information on the microprocessors used in
these applications.

i know that they typically work in a modular fashion with a central unit
that connects to smoke detectors, alarms etc.

can someone tell me what processor is typically used in this central unit?
eg 8bit,16 bit, motorola etc?

i have tried contacting manufacturers of such devices but none reply to
me:(

is there someone here who has such knowledge or an experienced person who
can make an educated guess on this device?

hope that you can help
andrew


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