Know your COM Port IRQ's, but other than that there's not much on it UNLESS you are take the Depot Technician secondary.
A+ 2006 is split between two mandatory certs, with one common one called A+ Essentials. Then there are three secondaries: IT Technician, Remote Support, and Depot Technician.
IT Technician is a good, well-rounded cert between hardware, operating system, and customer service knowledge.
Remote Support is more about customer service, operating system, with a bit of hardware.
Depot Technician is largely hardware specific, operationg system, with a little bit of customer service.
You only need to take Essentials and one secondary to get your A+.