Open Firmware

Open Firmware ( OFW or OF short ) is an open, cross-platform standard that a boot environment for operating systems of computer systems defined (open firmware for the boot process.) Open Firmware is standardized in IEEE 1275th

The functionality goes far beyond a typical PC BIOS. Distribution is OFW ultimately only on the SPARC and PowerPC architecture. Therefore, there is the firmware (BIOS and its dedicated followers EFI) has always pure x86 machine code and is also - except the children's laptop OLPC XO- 1, OFW could not prevail in the PC field of x86-compatible CPUs, despite the advantages not to other processor architectures portable.

Operation

Open firmware provides a command line as an optional boot prompt and supports programmable commands in the hardware-independent assembler near Forth programming language. About Open Firmware, manufacturers of auxiliary equipment (eg graphics cards) make their integration so that they are independent of the CPU. These defined an Open Firmware Forth variant, which can be stored in an intermediate code format called FCode on a read-only memory on the attachment.

OFW defines an environment that acts independently of the used processor and system as a kind of kernel (see virtual machine). Plug- readers can then log into the system with your own routines which can be potentially executed on each Open Firmware platform. Access to devices in the system is possible via a runtime environment. There, the devices are managed in a tree structure whose entries have a dynamic number of attributes.

Access to the device is also the loaded operating system is possible if the client interface has been implemented in the Open Firmware. Since the open- firmware environment sets narrow limits in which FCode drivers have to work with, they are often not very performant and only support the functions of the hardware that is needed to start. For this reason, the operating system usually takes relatively fast self control. The terminal console of Solaris on the SPARC architecture reaches for example back to the graphics card driver in the Open Firmware, which the console is very slow.

Even simple diagnostic functions can be performed before the actual boot, or there may be settings ( environment variables ) can be changed - like a Linux boot prompt, but much more flexible.

History

The first specification of Open Firmware is from Sun Microsystems.

Open Firmware was first SPARC architecture used in Sun Microsystems ' as OpenBootPROM, and then later adopted with the introduction of the PowerPC architecture for Apple's Macintosh computers.

In the PC area with x86-compatible CPUs OFW could not prevail, there is a trend towards EFI. Therefore, since the switch is based on the Intel architecture and Apple instead of OFW now Intel BIOS successor EFI one.

Areas of application

Open Firmware is used today on a variety of platforms, from single to large-scale computer system. To use Open Firmware comes eg with all systems from Sun Microsystems - but also on CHRP computers from Apple ( PowerMacs ) or other manufacturers that are based on the PowerPC architecture. For example, use the computer Pegasos I and - II and the EFIKA motherboards the company Genesi an Open Firmware.

The OLPC XO -1, the " One Laptop Per Child " initiative uses an x86 Open Firmware implementation together with an adapted Child - friendly Linux operating system.