ROM BIOS ManufacturersROM BIOS Manufacturers

Several popular BIOS manufacturers in the market today supply the majority of motherboard and system manufacturers with the code for their ROMs. This section discusses the various available versions.

Several companies have specialized in the development of a compatible ROM BIOS product. The three major companies that come to mind in discussing ROM BIOS software are American Megatrends, Inc. (AMI), Phoenix Technologies, and Award Software (now owned by Phoenix Technologies).

Each company licenses its ROM BIOS to motherboard manufacturers so those manufacturers can worry about the hardware rather than the software.

To obtain one of these ROMs for a motherboard, the original equipment manufacturer (OEM) must answer many questions about the design of the system so that the proper BIOS can be either developed or selected from those already designed.

Combining a ROM BIOS and a motherboard is not a haphazard task. No single, generic, compatible ROM exists, either. AMI, Award, Microid Research (MR BIOS), and Phoenix ship many variations of their BIOS code to different board manufacturers, each one custom tailored to that specific motherboard.

Recently, some major changes have occurred in the BIOS industry. Intel, the largest BIOS customer, has gone from using mostly Phoenix to using AMI, back to Phoenix, and now back to AMI for most of its motherboards. Intel originally used the Phoenix BIOS core in its motherboards up through 1995, when it changed to an AMI core.

It then used AMI until 1997, when it switched back to Phoenix. More recently in 1999 Intel switched again, this time back to AMI. In all these cases, Intel takes the core BIOS from Phoenix or AMI and highly customizes it for its particular motherboards.

It is always a big deal which BIOS Intel uses because Intel manufactures more motherboards than any other company. What that basically means is that if you purchase a PC today, you have a good chance of receiving an Intel-made motherboard with AMI BIOS.

Another development is that in late 1998, Phoenix bought Award. Although Phoenix continues to sell the Award BIOS as a separate product line, the big-three BIOS developers are now reduced to the big two—Phoenix and AMI. Many of the offshore motherboard manufacturers use the AMI or Award BIOS.

Phoenix not only develops the BIOS for many systems, but is also the primary BIOS developer responsible for new BIOS development and new BIOS standards. Current Phoenix BIOS products based on Phoenix BIOS 4.0 are known as FirstBIOS Pro, whereas Phoenix BIOS products based on Award BIOS are known as FirstBIOS.

Another development in recent years has been the creation of separate BIOS products for desktop, mobile, 32-bit and 64-bit server products, and embedded devices.

Although all BIOS chips must perform some of the same tasks, a BIOS product optimized for a mobile computer needs support for features such as docking modules and advanced battery power management, whereas a BIOS optimized for a server needs support for features such as advanced hardware monitoring and 64-bit PCI slots.

By creating customized BIOS versions for different platforms, BIOS vendors provide support for the features needed by a particular computing platform and provide better performance and stability.


Many OEMs have developed their own compatible ROMs independently. Companies such as Compaq, AT&T, and Acer have developed their own BIOS products that are comparable to those offered by AMI, Phoenix, Award, and others.

These companies also offer upgrades to newer versions that often can provide more features and improvements or fix problems with the older versions. If you use a system with a proprietary ROM, ensure that it is from a larger company with a track record and one that will provide updates and fixes as necessary.

Ideally, upgrades should be available for download from the Internet. Most OEMs have their BIOS written for them by a third-party company. For example, Hewlett-Packard contracts with Phoenix to develop the motherboard BIOS for some HP PCs.

Note that even though Phoenix might have done the development, you still must get upgrades or fixes from Hewlett-Packard. This is really true for all systems because all motherboard manufacturers customize the BIOS for their boards.


Although AMI customizes the ROM code for a particular system, it does not sell the ROM source code to the OEM. An OEM must obtain each new release as it becomes available. Because many OEMs don't need or want every new version developed, they might skip several version changes before licensing a new one.

The AMI BIOS is currently the most popular BIOS in PC systems. Some versions of the AMI BIOS are called Hi-Flex because of the high flexibility found in the BIOS configuration program. The AMI Hi-Flex BIOS products are used in Intel, AMI, and many other manufacturers' motherboards.

One special AMI feature is that it is the only third-party BIOS manufacturer to make its own motherboards and other hardware devices. During power up, the BIOS ID string is displayed on the lower-left part of the screen. This string tells you valuable information about which BIOS version you have and about certain settings that are determined by the built-in setup program.

The primary BIOS Identification string (ID String 1) is displayed by any AMI BIOS during the POST in the bottom-left corner of the screen, below the copyright message. Two additional BIOS ID strings (ID Strings 2 and 3) can be displayed by the AMI Hi-Flex BIOS by pressing the Insert key during the POST. These additional ID strings display the options installed in the BIOS.

The AMI BIOS has many features, including a built-in setup program activated by pressing the Delete or Esc key in the first few seconds of booting up your computer. The BIOS prompts you briefly as to which key to press and when to press it.

The AMI BIOS offers user-definable hard disk types, essential for optimal use of many IDE or ESDI drives. The 1995 and newer BIOS versions also support enhanced IDE drives and autoconfigure the drive parameters.

A unique feature of some of the AMI BIOS versions was that in addition to the setup, they had a built-in, menu-driven diagnostics package—essentially a very limited version of the standalone AMIDIAG product. The internal diagnostics are not a replacement for more comprehensive disk-based programs, but they can help in a pinch.

The menu-driven diagnostics do not do extensive memory testing, for example, and the hard disk low-level formatter works only at the BIOS level rather than at the controller register level. These limitations often have prevented it from being capable of formatting severely damaged disks.

Most newer AMI BIOS versions no longer include the full diagnostics. AMI doesn't produce BIOS documentation; it leaves that up to the motherboard manufacturers who include their BIOS on the motherboard.

However, AMI has published a detailed version of its documentation called the Programmer's Guide to the AMIBIOS: Includes Descriptions of PCI, APM, and Socket Services BIOS Functions, published by Windcrest/McGraw-Hill, ISBN 0-07-001561-9. This book, written by AMI engineers, describes all the BIOS functions, features, error codes, and more.

Unfortunately, this book is out of print. If you can locate it (try searching with Google or at, I recommend this book for users with an AMI BIOS in their systems because this provides a complete version of the documentation for which they might have been looking.

The AMI BIOS is sold through distributors, a list of which is available at its Web site. However, keep in mind that you can't buy upgrades and replacements directly from AMI, and AMI produces upgrades only for its own motherboards. If you have a non-AMI motherboard with a customized AMI BIOS, you must contact the motherboard manufacturer for an upgrade or use a third-party BIOS upgrade vendor


Just as Award Software did before its merger with Phoenix, Phoenix continues to sell the Award BIOS code to the OEM and allows the OEM to customize the BIOS; Phoenix now refers to the Award BIOS as FirstBIOS. This permits the OEM to have total control over the BIOS code without having to write it from scratch.

By contrast, neither the Phoenix BIOS nor the AMI BIOS source code is sold to OEM customers. Phoenix and AMI customize their BIOS code for each customer's needs, but they retain control of it. Some OEMs that seem to have developed their own ROM code started with a base of source code licensed to them by Award or some other company.

FirstBIOS has all the features you expect, including a built-in setup program activated by pressing Ctrl+Alt+Esc or a particular key on startup (usually prompted on the screen). This setup offers user-definable drive types, required to fully use IDE or ESDI hard disks.

The POST is good, although the few beep codes supported means that a POST card is necessary if you want to diagnose most power-on problems. Phoenix provides technical support on its Web site. (formerly Unicore Software) provides Award BIOS upgrades for end users.


The Phoenix BIOS (now sold by Phoenix as FirstBIOS Pro) for many years has been a standard of compatibility by which others are judged. It was one of the first third-party companies to legally reverse-engineer the IBM BIOS using a clean-room approach.

In this approach, a group of engineers studied the IBM BIOS and wrote a specification for how that BIOS should work and what features should be incorporated. This information then was passed to a second group of engineers who had never seen the IBM BIOS.

They could then legally write a new BIOS to the specifications set forth by the first group. This work was then unique and not a copy of IBM's BIOS; however, it functioned the same way. The Phoenix (FirstBIOS Pro) BIOS excels in two areas that put it high on my list of recommendations.

One is that the POST is excellent. The BIOS outputs an extensive set of beep codes that can be used to diagnose severe motherboard problems that would prevent normal operation of the system. In fact, with beep codes alone, this POST can isolate memory failures in Bank 0 right down to the individual SIMM or DIMM module.

The Phoenix BIOS also has an excellent setup program free from unnecessary frills, but one that offers all the features the user would expect, such as user-definable drive types and so on. The built-in setup is activated by pressing Ctrl+Alt+S; Ctrl+Alt+Esc; or a particular key on startup, such as F1 or F2 on most newer systems, depending on the version of BIOS you have.

The second area in which Phoenix excels is the documentation. Not only are the manuals you get with the system detailed, but Phoenix has also written a set of BIOS technical reference manuals that are a standard in the industry.

The original set consists of three books, titled System BIOS for IBM PC/XT/AT Computers and Compatibles, CBIOS for IBM PS/2 Computers and Compatibles, and ABIOS for IBM PS/2 Computers and Compatibles; an updated version is called System BIOS for IBM PCs, Compatibles, and EISA Computers: The Complete Guide to ROM-Based System Software.

In addition to being excellent references for the Phoenix BIOS, these books serve as an outstanding overall reference to the BIOS in general. These are out of print but might be available through bookfinder services such as

Phoenix has extensive technical support and documentation on its Web site, as does its largest nationwide distributor, Micro Firmware, Inc. You also can check the phone numbers listed in the Vendor List on the DVD.

Micro Firmware offers upgrades to some older systems with a Phoenix BIOS, including many Packard Bell, Gateway (with Micronics motherboards), Micron Technologies, and other systems. For most systems, especially newer ones, you need to get any BIOS updates from the system or motherboard manufacturer.

These companies' products are established as ROM BIOS standards in the industry, and frequent updates and improvements ensure that a system containing these ROMs will have a long life of upgrades and service.

Microid Research BIOS

Microid Research (MR) is an interesting BIOS supplier. It primarily markets upgrade BIOS for older Pentium and 486 motherboards that were abandoned by their original manufacturers. As such, it is an excellent upgrade for adding new features and performance to an older system. Microid Research BIOS upgrades are sold through (Unicore Software).