Although MacBook doesn’t have Bios but it is supported with a similar boot firmware used by Sun and Apple called Open Firmware. Open firmware is a platform independent boot firmware. It is very similar to BIOS in windows. Its implementation is based on Forth programming language (FCode dialect). Now you must be thinking how to enter in your Macbook Pro Bios?

FCode- FCode is a Forth dialect compliant to ANS Forth, that is available in two different forms: source and bytecode.FCode source compiled form is FCode bytecode. (source:

Open Firmware on Startup

To access Open Firmware in your MacBook, first shut down your MacBook. Turn it back on, holding down the “Command”, “Option”, “0” and “F” keys simultaneously as the machine boots. Like BIOS in windows, the Open Firmware command terminal is two-tone and doesn’t provide extensive prompts.

The first prompt says “ok” which signifies that the MacBook is functioning properly and Open Firmware is ready to begin submitting commands.

Macbook Pro BIOS

MacBook Pro Device Tree

At first glance, MacBook may look like a single mechanism. The machine is composed of various devices that work in a congregation with the operating system. Besides USB hub, keyboard and mouse, there exists a bus, battery, fan and the root device that act as a central channel through which other devices are controlled. The command for accessing the device tree through the Open Firmware command terminal is “dev/ls”. It displays the device in a sequence of their device code and corresponding function.




Macbook Pro BIOS


RAM Configuration

There are two types of memory storage in your system, out which one is RAM. RAM stands for random access memory, which performs all legal works in your system. The firmware terminal allows you to display the configuration using the command “dev /memory .properties”. It is displayed according to the number of DDR SDRAM cartridges you have installed on your system.


Macbook Pro BIOS

CPU Information

CPU stands for Central Processing Unit. It is the most important unit on any system responsible for the fundamental logic of the system. It performs all the input and output operations in the system. The Firmware interface allows you to view information regarding CPU. The command to view CPU information on the terminal use command “dev /cpus”. It displays the kind of microprocessor the system is outfitted with, its clock frequency and its bus frequency. The Firmware terminal also allows you to run diagnostic testing on the microprocessor.

Well this was all about how to enter Macbook Pro BIOS or access your Macbook’s Open Firmware. Hope it was a relevant post for all the users. For any further updates , stay tuned to YourSpot !!!


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