Replacing a BIOS ROM

Systems dating from 1995 or earlier usually don't have a flash ROM and instead use an EPROM. To upgrade the BIOS in one of these systems, you replace the EPROM chip with a new one preloaded with the new BIOS. As with a flash ROM upgrade, you must get this from your motherboard manufacturer.

There is usually a fee for this because the manufacturer must custom-burn a chip just for you and mail it out. Most boards older than 1995 are probably not worth upgrading the BIOS on, so weigh this option carefully!

It doesn't make sense to spend $50 on a new BIOS for an ancient board when a new Pentium or Pentium II board can be had for $75, and that new board will include a flash BIOS and many other new features.

The procedure for replacing the BIOS chip is also useful if you have made a backup copy of your socketed system BIOS chip and need to replace a damaged original with the backup copy.

To replace the BIOS chip, follow these steps:

  1. Back up the CMOS RAM settings.

  1. Power down the system and unplug the power cord.

  1. Remove the cover and any other components in the way of the BIOS EPROM chip. Remember to use caution with respect to static discharges; you should wear an antistatic wrist strap for this procedure or ground yourself to the chassis before touching any internal components.

  1. Using a chip puller or a thin flat-blade screwdriver, gently pry the chip out of its socket.

  1. Remove the new EPROM from the antistatic packing material in which it came.

  1. Install the new EPROM chip into the socket. A standard rectangular BIOS chip has a dimple at one end that corresponds to a cutout on the socket. You can install the chip in the socket backward, but if you do, you will destroy the chip.

  1. Reinstall anything you removed to gain access to the chip.

  1. Put the cover back on, plug in the system, and power on.

  1. Enter the BIOS setup information you saved earlier.

  1. Reboot and enjoy the new BIOS!

As you can see, things are much easier with a modern motherboard with a flash ROM because you usually don't even have to remove the lid (unless the flash BIOS is write-protected as discussed earlier).