Implementing ROM - which FPGA to use?

Hi all,

I need to implement 5 look-up tables (for 5 DACs), with a total of ~800Kbits.

I built a simple rom (didn't use a mega-function) - an entity with address and data pins and an internal array which has the data hardcoded inside. When I compiled the project I found that the FPGAs logic elements were almost entirely used (98%) but the memory bits weren't used at all. My questions are (sorry if they are too simple :) ):

1. What is the difference between logic elements and memory (in an FPGA)?

1. Why was my code tranlated into logic elements and not memory?

2. Is there a way to use the memory bits for the rom (instead or along with the logic elements)

Thanks in advance