Firmware

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A typical firmware-controlled device, a television remote control. Consumer products like this have been using firmware since the 1970s.

In electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices. Typical examples of devices containing firmware range from end-user products such as remote controls or calculators, through computer parts and devices like hard disks, keyboards, TFT screens or memory cards, all the way to scientific instrumentation and industrial robotics. Also more complex consumer devices, such as mobile phones, digital cameras, synthesizers, etc., contain firmware to enable the device's basic operation as well as implementing higher-level functions.

There are no strict boundaries between firmware and software, as both are quite loose descriptive terms. However, the term firmware was originally coined in order to contrast to higher level software which could be changed without replacing a hardware component, and firmware is typically involved with very basic low-level operations without which a device would be completely non-functional. Firmware is also a relative term, as most embedded devices contain firmware at more than one level. Subsystems such as CPUs, flash chips, communication controllers, LCD modules, and so on, have their own (usually fixed) program code and/or microcode, regarded as "part of the hardware" by the higher-level(s) firmware.

Low-level firmware typically resides in a PLA structure or in a ROM (or OTP/PROM), while higher level firmware (often on the border to software) typically employs flash memory to allow for updates, at least in modern devices. (Common reasons for updating firmware include fixing bugs or adding features to the device. Doing so usually involves loading a binary image file provided by the manufacturer into the device, according to a specific procedure; this is sometimes intended to be done by the end user.)

Thus, while high-level firmware (or software) typically is stored as a configuration of charges, low-level firmware may instead often be regarded as actual hardware in itself. For instance, older firmware was often implemented as a discrete semiconductor diode matrix. The modern equivalent is an integrated matrix of field effect transistors where 0's and 1's are represented by whether a particular component in the ROM and/or PLA matrices is present or not.

Origin of the term

Ascher Opler coined the term "firmware" in a 1967 Datamation article.[1] Originally, it meant the contents of a writable control store (a small specialized high speed memory), containing microcode that defined and implemented the computer's instruction set, and that could be reloaded to specialize or modify the instructions that the central processing unit (CPU) could execute. As originally used, firmware contrasted with hardware (the CPU itself) and software (normal instructions executing on a CPU). It was not composed of CPU machine instructions, but of lower-level microcode involved in the implementation of machine instructions. It existed on the boundary between hardware and software; thus the name "firmware".

Later[when?] application of the term broadened to include any type of microcode, whether in writable control store or read-only control store.

Still later, popular usage extended the word "firmware" to denote anything ROM-resident, including processor machine-instructions for BIOS, bootstrap loaders, or specialized applications.

Until the mid 1990s, updating firmware to a new version typically involved replacing a storage-medium containing firmware, usually a socketed ROM. As of 2009 firmware-upgraders have largely abandoned this approach in favor of using firmware's capability to overwrite itself in a convenient, purely electronic operation.

Firmware as of 2011

Today, in some circles, the word firmware has evolved to sometimes even denote application-level programs stored in NAND flash or NOR flash memory (such as in mobile phones and similar products). However, a more fundamental definition would still be fixed or semi-fixed data in a hardware device. This may include ROM and/or PLA structures for microcode and other data in a processor implementation as well as the low level machine code stored in ROM or flash memory running on that processor (i.e. many products use several levels of firmware). Microcode and other data in an application-specific integrated circuit (ASICs) would also fit that definition very well. The same could be said about programmable logic devices which may have configuration data stored either as internal fuses, in a ROM, or in a flash memory (used much the same way as a ROM or EPROM).

Personal computers

ROM BIOS firmware on a Baby AT motherboard

In some respects, the various firmware components are as important as the operating system in a working computer. However, unlike most modern operating systems, firmware rarely has a well-evolved automatic mechanism of updating itself to fix any functionality issues detected after shipping the unit.

Currently, devices like video cards, sound cards or modems in a modern PC often rely on firmware dynamically loaded by a device driver and may thus get transparently updated through the operating system update mechanisms. The BIOS may be "manually" updated fairly easily by an educated user, using a small utility program. In contrast, firmware in storage devices (harddisks, DVD-drives, flash-storage) rarely gets updated, even when flash (rather than ROM) storage is used for the firmware; there are no standardized mechanisms for detecting or updating firmware versions. However, in practice, such devices have a low rate of functionality issues compared to parts where the firmware may be updated. This is because, in most cases, only small incremental changes to the code are needed for new product generations. The bulk of the code is therefore typically well proven and tested compared to completely new, or less critical, products. The amount of in depth design analysis and serious testing also varies heavily among different product groups in general, according to market demands, corporate culture and other factors.

Computer peripherals

Most computer peripherals are themselves special-purpose computers. While external devices (printers, scanners, cameras, USB drives,...) have firmware stored internally, modern graphics cards and peripheral expansion cards often have parts of the firmware loaded by the host system at start-up, as this provides greater flexibility. Such hardware may therefore fail to function fully until the host computer has "fed" it the requisite firmware, typically via a specific device driver (more exactly: via a start-up subsystem within a device driver package). Modern device drivers, whether for internal or external "peripheral" devices, may also expose a direct graphical user-interface for configuration, often using parts of a normal application programming interface in addition to lower level operating system calls, hooks, and/or other interfaces designed for device drivers.

Consumer products

As of 2010 most modern portable music players support firmware upgrades. Some companies use firmware updates to add new playable file formats (encodings); iriver added the Vorbis format this way, for instance. Other features that may change with firmware updates include the GUI or even the battery life. Most mobile phones have a Firmware Over The Air firmware upgrade capability for much the same reasons; some may even be upgraded to enhance reception or sound quality, illustrating the fact that firmware is used at more than one level in complex products (in a CPU-like microcontroller versus in a digital signal processor in this particular case).

Automobiles

Since 1996 most automobiles have employed an on-board computer and various sensors to detect mechanical problems. As of 2010 modern vehicles also employ computer-controlled ABS systems and computer-operated Transmission Control Units (TCU). The driver can also get in-dash information while driving in this manner, such as real-time fuel-economy and tire-pressure readings. Local dealers can update most vehicle firmware.

IEEE Definition

Institute of Electrical and Electronics Engineers (IEEE) Standard Glossary of Software Engineering Terminology, Std 610.12-1990, defines firmware as follows:

"The combination of a hardware device and computer instructions and data that reside as read-only software on that device.
Notes: (1) This term is sometimes used to refer only to the hardware device or only to the computer instructions or data, but these meanings are deprecated. (2) The confusion surrounding this term has led some to suggest that it be avoided altogether."

Examples

Examples of firmware include:

Firmware hacking

Sometimes third parties create an unofficial new or modified version of firmware to provide new features or to unlock hidden functionality. Examples include:

Most firmware hacks are free and open source software as well.

These hacks usually take advantage of the firmware update facility on many devices to install or run themselves. Some, however, must resort to exploits in order to run, because the manufacturer has attempted to lock the hardware to stop it from running unlicensed code.

Newer custom firmware hacks have also focused on injecting malware in devices such as smartphones. Example of one such is of Symbian OS, which was recently demonstrated at MalCon,[5][6] a hacker convention.

See also

References

  1. ^ Opler, Ascher (1967). "Fourth-Generation Software". Datamation. 13 (1): 22–24. {{cite journal}}: Unknown parameter |month= ignored (help)
  2. ^ a b c "Custom Firmware Rocks!". 2009-08-05. Retrieved 2009-08-13.
  3. ^ "Magic Lantern firmware for Canon 5D Mark II". Retrieved 2009-08-13.
  4. ^ "SamyGO: replacing television firmware". LWN.net. 2009-11-14. Retrieved 2009-12-11.
  5. ^ http://www.malcon.org
  6. ^ http://www.h-online.com/security/news/item/Hacker-plants-back-door-in-Symbian-firmware-1149926.html
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