Design Recipes for FPGAs: Using Verilog and VHDL

10

Memory

Introduction

If we consider SDRAM (Synchronous Dynamic Random Access

Memory), the key aspects of this type of memory to consider are:

1. This type of DRAM (Dynamic RAM) relies on transistor

capacitance on gates to store data.

2. DRAM is much more compact than SRAM (Static RAM).

3. DRAM cannot be synthesized – you need a separate DRAM

chip.

4. SDRAM requires a synchronization clock that is consistent

with the rest of the hardware system (it is designed to operate

with microprocessors).

5. DRAM data must be refreshed as it is stored charge and

decays after a certain time.

6. DRAM is slower than SRAM.

Static RAM (SRAM) can be considered in a similar way to a

Read Only Memory (ROM) chip and it also has (differing) key

aspects of behavior to consider: ...