MAP vs MAF, again

[bamcknig at postoffice.syspac.com]

Bruce

I need a Map, not an MAP..
I am lost.  MAF is a MASS AIR FLOW sensor.  usually a hot wire or 
plate type?  MAP is a Manifold Air Pressure sensor?  What measures 
Atmospheric pressure(in a boat its a barometer)?  How do I get 
Speed -Density?  One or two sensors?

Bob McKnight
Phx AZ
                                    PS-
These alphabets get me.  At tax time I find myself putting a 1040 in 
my independent rear supension(IRS) and sending a 4:11 to the internal 
revenue system(IRS).  My USB(universal serial bus) won't plug into my 
USB(upper Side Band) ham radio set.  Although I hear if I buy a new 
transceiver I will be able to plug my USB into my USB.  Between the 
Hieroglyphics on my computer screen and  the alphonics of the 
Technical publications, I am losing what little command of the 
english language I had.