It is possible and sometimes desired to modify your BIOS, especially on older PCs. Examples of what you can get out of it:
wider device support: disks over 32G, more kinds of CPUs
cosmetic improvements: changing or disabling the Energy Star logo
including custom ROMs: Plop boot manager can boot straight from USB
It is advisable to obtain a second FlashPROM/EEPROM chip of at least the same size (scrap motherboards are a good source), and swap them just before flashing. This operation is slightly risky as you need to be careful not to bend the legs of the original chip while pulling it out—you need to pull on both sides of the chip with close to equal force. The legs will easily break off if you keep bending them. You can help yourself avoid the problem by stuffing a piece of non-conductive material underneath/around the replacement chip so that you get something to pull on. There’s also no need to push it all the way down, you just need to make stable contact on all legs. Make sure the chip is inserted in the right orientation, or you will destroy it—there should be some indication on the motherboard if you haven’t noted it before removing the old one.
There is no universal scheme to chip labeling, however the name is in general composed of a manufacturer code (W/Pm/…), a two-digit number (27/39/49/…), a letter (C/…), and a number representing size: 1Mbit (128kB) PROMs contain a 1 and some zeroes (001/010/100), while 2 Mbit (256kB) contain a 2 and some zeroes (002/020/200).
Otherwise read up on flashing back the original BIOS from the boot block.
Most tools work from DOS, so that’s what I concern myself with here. If you can’t boot to DOS as part of your Windows operating system, either create an additional small FreeDOS partition on your harddrive, or load files to a bootable floppy—you will need read/write access. For operations that don’t need access to the BIOS chip, you may also use a virtualised environment.
Award has an official tool for backing up and flashing, called AWDFLASH. Note that the latest version of it may not work. Specifically I experienced a failure with AWDFLASH 8.99 but version 8.00 showed no issues.
Alternatively you may use UNIFLASH, just be aware that it only seems to work in FreeDOS’s "Safe mode".
CBROM is an official tool to modify BIOS images.
With MODBIN you can change some settings within the BIOS, such as enable or disable menu items, or change various texts. One of the normally disabled menu items on deals with showing or hiding the useless Energy Star logo.
AwardBIOS 6 requires MODBIN6. Versions 2.04.01 and above only work in Windows.
There are some issues that can be automatically addressed by this tool, such as fixing support for large harddrives, or adding support for more CPUs. The latest stable version of this tool is 4.23 and I haven’t seen it do anything useful for my newer machine with AwardBIOS 6.
This boot manager can be integrated within the BIOS as a PCI option ROM, allowing you to boot from USB devices and even individual disk partitions (though not the MBR for whatever reason).
Download the Linux package, set up the image according to your liking with
plpcfgbt and create an option ROM with plpbtrom (use the
switch to make sure it fits, doing so costs nothing).
Finally add it to your BIOS image under DOS like
cbrom image.bin /pci plpbtrom.bin
Under normal circumstances it will be invoked when you tell AwardBIOS to boot from the network, and can be disabled by pressing D when given the option.
In theory you should be able to configure the image with
plpbtrom with an additional
-nodisable switch, put LAN at the start of your
BIOS boot sequence and have Plop run on request by pressing Ctrl-A, however it
seems it fails to do a "far return" back to BIOS for me, and I have to make do
with changing the boot sequence each time I want to make use of Plop.
AWDFLASH refused to flash my ROM unless I used the /QI switch. One chip I had also just failed to be flashed altogether, for unknown reasons.
Since information and files are starting to disappear from the Web, I’m sharing here a backup of all the tools, unmodified.