Using RBE

Whatever method you used to acquire your BIOS, assume you're back in Windows now having the BIOS file(s) somewhere. The file should be about 64 kB or 128 kB in size. The first thing you should do is save a copy of that original BIOS to a secure place. You should also keep a copy of that file on your bootable device (see section 2). Have one copy of the BIOS file named something like "Sapphire 4870 - Copy for RBE.rom" so you always know this is the file you play around with. However, you don't need to change that file - you can save the modified file using a completely different name (see section 3.8), your choice.

Opening the BIOS file

There are several methods to open the file:

• Drag and drop the file onto the RBE icon. Put a link to the program on your desktop for most comfort
• Drag and drop the file somewhere into the already started program
• Use the command line - that is, use a DOS prompt from inside Windows or use the Start... Run as... feature
• Inside the program, click on the "Load BIOS..." button at the bottom left
• Pressing Alt+L has the same effect
• or, also inside the program, click on the "File... Load BIOS..." in the menu bar.

First steps - The information tab

You can see a screenshot of RBE after a file was loaded.

• At first, you notice that the "Information" tab is selected. You see what file exactly has been loaded together with the complete path to it.
• In the BIOS information frame, there are several status reports on the file. First of all, there is the date and time that BIOS file has been compiled. You can change this, but you shouldn't. This section inside the BIOS file is protected by a digital signature. Changing the date/time information will most likely make the driver not recognize the card any more. We'll discuss that problem later (see section 3.2).
• The next thing is the BIOS version string. This and all following strings are not protected, so feel free to change this and any other of the following information to anything you like.
• The reported chip type tells you, what type of chip your video card uses. Note that several chips can be used on different video cards. For example, the RV670 you see here is used on the 3870, but also on the 3850.
• The hardware specs string is supposed to tell more about the hardware. As you see here, it contains the memory bus width and the default clock rates. However, it's not as clear as it is here for most BIOSes. Sometimes, no useful information can be taken from here. This string is purely informational, changing it will not change any operating parameters of your card.
• The copyright message tells you that ATI is the copyright owner of this BIOS.
• The AtomBIOS version tells you the version of the tool video card vendors used to create this BIOS. This is in no way related to the BIOS version string above.
• Did you ever put your card into the computer and switched on the machine without plugging the special video card's power cable into the card? Then you saw the power cable error message on the screen. You can change this too, of course. Note that for cards without a special power cable, this message may, but may be not displayed.
• Then there is the "BIOS had been pre-modified" checkbox. You can't change that checkbox, it's just for RBE to tell you that you opened a stock BIOS (like in this case) or the BIOS you opened was edited in the past using RBE, if the box is checked. Note that in rare cases, this checkbox is checked even for stock BIOSes. That happens if the BIOS violates several standards and is not so nice, but in no way alarming.
• The next thing is the BIOS checksum. You will be displayed that if using ATIFlash or WinFlash to compare two (or a bunch of) BIOSes. WinFlash calls is "CRC" and displays both checksums, the one of your actual video card and the one of the file you loaded into WinFlash. To make ATIFlash tell you a BIOS file's checksum, use the parameter -cf, so you enter "ATIFlash -cf BIOS.ROM" for example. To view the video card's BIOS checksum, enter "ATIFlash -cb 0" for the checksum of adapter 0.
• WinFlash also tells you the actual video card's BIOS size and the size of a BIOS image as well. Winflash just views it like that, ATIFlash can't view it. However, you have this information in RBE anyway.
• WinFlash sometimes calculates the checksum wrongly. The problem is that inside the BIOS there is an information on how big the BIOS is. This information might be incorrect. WinFlash doesn't just take the size of the BIOS (in other words: The file's size) as a basis for calculating the checksum, but this sometimes incorrect size information. This has also something to do with PCI specifications. The problem with the corrupt 4870 BIOSes you may heard of has to do with that, too. Without going into too much detail here, just notice that the checksums may differ (see next screenshot). In that case, you have to keep both checksums in mind for flashing the BIOS later (see section 4).
  
  
• The next line will tell you how much RAM the card has. This information is taken from the hardware specs string (see second last screenshot). You might find that hard to believe, but if this information is not contained inside the specs string, there is no information on memory size inside the BIOS! The card figures it out itself on boot up. For RBE, this means that in case this information isn't contained in the specs string, the information can't be taken from the BIOS file. So if there is nothing displayed here (see last screenshot), don't worry about it. However, you can't change anything here, of course.
• The RAM type is always contained inside the BIOS, RBE always has something to display here.
• The statement for the RAM amount holds here, too: If information on the RAM interface is not contained inside the specs string, RBE can't display anything.
• However, the video card interface can be displayed for all BIOSes again.
• On the right side, there is the vendor and the device ID. If you have a card from, say, ASUS, it can happen that the display states "0x1002 - ATI..." however. Many video card vendors seem to simply forget to put their vendor ID into the BIOS or use the ATI stock BIOS. You can change this information (as well as the device ID), but this is again protected using that digital signature described earlier. So after changing this and flashing such a BIOS to the card, Catalyst might not recognize the card anymore. However, there's no point in changing one of those items anyway. You can't turn a 2900 Pro wondrously into a 4870X2.