Q. Explain about Unified Memory Architecture?

UMA signifies Unified Memory Architecture. It is an architecture that reduces the cost of PC construction.  In this a part of main memory is essentially used as frame buffer.  Therefore it removes the use of a bus for video processing.  So it is less costly. However it isn't supposed to perform as well as AGP etc. in somecases it may give a better performance than bus-based systems. It's the interface used these days in low-cost motherboards. 

Figure:  AGP Video Architecture and its working