The fundamental difference between embedded and external memory devices lies in their physical location relative to the main processing chip. Embedded memory devices are memory devices that are integrated on to the chip with the logic core, while external memory devices are memory devices that reside outside the chip.
Core Distinction
This distinction is crucial in how memory is accessed and utilized within electronic systems. Think of the chip (often called the System-on-Chip or SoC in modern devices) as the brain containing the processor or logic core.
| Feature | Embedded Memory Device | External Memory Device |
|---|---|---|
| Location | Integrated on the same chip as the logic core | Resides outside the main processing chip |
| Integration | Highly integrated | Separate component |
| Connectivity | Direct connection (on-chip) | Requires off-chip connections (pins, buses) |
Usage and Examples
Embedded memory is typically used for tasks requiring high speed and low power consumption, often located very close to the processor for quick access.
Examples of embedded memory types include:
- Embedded SRAM (Static Random-Access Memory): Used for caches and small buffers within the chip.
- Embedded ROM (Read-Only Memory): Stores boot-up code or configuration data directly on the chip.
The reference highlights that Embedded SRAM and ROM are widely used than external or stand alone SRAM and ROM. This preference often stems from performance advantages and potentially lower power consumption when memory is tightly integrated.
External memory, on the other hand, is used when larger capacities are needed, even if access is slightly slower due to the distance and off-chip communication.
Examples of external memory types include:
- External DRAM (Dynamic Random-Access Memory): Commonly used as the main system memory (RAM) in computers and smartphones.
- External Flash Memory: Used for persistent storage like SSDs or SD cards.
Practical Implications
The choice between embedded and external memory impacts system design in several ways:
- Speed: Embedded memory generally offers faster access times due to its proximity and direct connection to the logic core.
- Power Consumption: On-chip communication typically consumes less power than off-chip signaling.
- Cost and Density: External memory often provides higher storage density at a lower cost per bit, making it suitable for large capacity needs.
- Space: Embedded memory utilizes space on the processor die, while external memory requires separate components on the circuit board.
In summary, embedded memory is tightly integrated with the processing unit for speed and efficiency, while external memory provides greater capacity and flexibility as separate components.
