In electronic systems and computing, firmware is a software that can connect to specific hardware that provides the low-level control. Every device comes with its own firmware based on the product manufacturer.
The following list of categories and types of devices are those that typically come with custom firmware, which are mostly Linux. The following does not cover the entire list in any way:
The following table provides the type of memory utilized in most of the embedded devices:
|
Type of memory |
Description |
|
DRAM (Dynamic Random-Access Memory) |
Volatile memory that can be accessed in both read and write mode. It is fast and will need access to the memory contents. DRAM is the reason to employ caching mechanisms in some architectures. The DRAM memory access is timed at the very early stages of bootloader. |
|
SRAM (Static Random-Access Memory) |
Another volatile memory similar to DRAM can be accessed in read and write mode. It is fastest compared with DRAM. Mostly, small levels of SRAM that are less than 1 MB will be included on the device (due to commercial reasons). |
|
ROM (Read-Only Memory) |
This is non-volatile memory that can only be read. A mask bootloader is one example of a ROM in embedded devices. |
|
Memory-Mapped NOR Flash |
Another non-volatile memory that can be accessed in read/write mode. This is used during bootcode. |
|
NAND Flash |
Type of non-volatile storage technology that does not require power to retain data. |
|
SD (Secure Digital) Card |
Non-volatile memory card format used in portable devices. |