PhoenixBIOS

PhoenixBIOS is a personal computer BIOS developed by Phoenix Technologies since 1983. It is the first IBM PC compatible BIOS that was legally licensed to other system vendors, and thus its release marks the beginning of the competition between Phoenix and other commercial BIOS vendors who later developed their own solutions for the same purpose (such as American Megatrends with their AMIBIOS and Award Software with their AwardBIOS).

Since the late 2000s and early 2010s, it has been mostly replaced by SecureCore, which is Phoenix's UEFI solution meant as a successor to it.

Reverse engineering of the IBM BIOS

Prior to its introduction, to build compatible clones of the IBM PC XT, vendors attempted to implement their own compatible solutions by copying portions of the IBM BIOS source code from reference manuals, which was illegal due to copyright infringement and usually resulted in legal action being taken.

Phoenix developed its solution using a method called the "Chinese Wall" to avoid copyright infringement. Using this method, one group of their engineers first read the reference manuals to reverse engineer various functions of the BIOS, documenting how they worked without writing any actual code, and then passed those documents to another engineer who wrote his own code to mimic those functions. According to Phoenix's Vice President of Marketing, Lance Hansche, "He (the engineer) was a TI-9900 programmer" and that "The TI-9900 processor (Texas Instruments TMS9900) is stack oriented, it doesn't have registers like the (Intel) 8088" and also that "There's no way his code could be the same as IBM's, it took us 3 months of memos to convince him to use registers at all!". During this process, the audit trail of both groups' interactions was also recorded to prove the legality of their implementation.

Since the engineer who wrote the BIOS never looked at the reference manuals, he could not have copied the IBM BIOS source code, so this implementation did not violate IBM's copyright and was therefore legal.

List of known versions

The following is a list of known versions of PhoenixBIOS.

Main version	Release date	Variants	POST screen	Notes
Phoenix ROM BIOS Ver 1.xx	1984
Phoenix ROM BIOS Ver 2.xx	1986(?)
Phoenix ROM BIOS PLUS	1987			A code fork by Dell exists, which was in use until around 2015. Likely internally considered as PhoenixBIOS 3.xx by Phoenix.
PhoenixBIOS 4.0x	1988	NoteBIOS 4.0 (1993?-1996) ServerBIOS (1996?)		A code fork by Intel exists, usually used on their very early motherboards.
PhoenixBIOS Ax86	1990(?)
PhoenixBIOS 4.0 Release 6.x	1997	NoteBIOS 4.0 Release 6 (1997-2003) ServerBIOS (4.0 Release 6 edition, 1997-1998) ServerBIOS 2 (1999-2000) ServerBIOS 3 (2001) ServerBIOS 3.5 Grid Edition (2002-2003)		Also used by VMware for the legacy BIOS option. Code forks by Intel and Siemens-Nixdorf/Fujitsu-Siemens also exists, with the latter usually being called "PhoenixBIOS 4.06". This fork may also be based on a pre-release version.
Phoenix cME FirstBIOS	2004