Firmware Development

Question

I want to clarify before the question that I am not an established professional programmer in any position at any firm. This is solely to satisfy curiosity, and will not pertain to any task or project at this time.

As I understand it, firmware is software placed on hardware to grant it autonomous functionality from instructions, which is given through some form of input; As long as the input stream is readable, which is made possible through drivers. Drivers are software packages with pre-written reference libraries that recognize a specific set of instructions for each possible function in the attached device.

NOTE: not quoted, so I'm aware that this could be inaccurate.

What I want to know is how firmware or drivers are placed on devices without installation through an OS or storage medium; such as a DVD or USB? Specifically firmware installed by manufacturers, like bios and keyboard drivers that are present on all computers. I'm assuming these are less or not reliant on compilation in order to function properly, which is the sole reason I'm asking this question.

Can firmware be developed without compilation?

References

• Demystifying Firmware

• C++ Kernel Development

• Starting Firmware Development

These just explain that an OS is a type of firmware, and that firmware is primarily developed in C with Assembly and C++ as plausible alternatives; pertaining to kernel development as well.

Answer 1

Yes, especially in the larger components. An example involving lua is http://nodelua.org/doc/index/

However, firmware development is typically an extremely memory (and frequently CPU) constrained environment.

C (or traditionally, assembler) is often preferred because it can produce extremely small executables, and is very efficient in stack usage. This matters when you're counting memory in bytes, or kilobytes.

Using a non-compiled language means you need to include a tiny interpreter, and you might not be able to set aside enough memory for this.

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You've made an edit, wherein you suggest that an "OS is a type of firmware". This can be true, in a manner of speaking.

Often firmware itself can consist of an operating system, with components. As an example, the firmware in some home internet routers will contain an OS (which might very well be linux!), however it is still regarded as firmware. There is a bit of a grey area between a computer that is an "embedded device with firmware", vs that of a 'regular computer with regular software', but generally firmware is a computer system running in a very constrained environment, often with very specific uses.

NetBSD includes Lua in it's kernel. Many systems have been developed that do not use Assembly (except for a small part of it), C, or C++, but instead use some other language - though it is typically still compiled for size and performance reasons.

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As for the actual transfer of firmware (whatever the form it may be in), this depends on the device in question.

Some devices require that the firmware be burned into the components. (In ROM, though there are various types of ROM and some can be rewritten).

Other devices require that the firmware be transferred when the device is turned on.

And yet others have SDCards or battery-backed RAM or whatever that allow storing the firmware across reboots.