Hardware - Hot Flashing the BIOS

There are numerous cases in which you need to flash new BIOS image to your Flash ROM: You downloaded a new BIOS for your motherboard and the flash program freezed during flashing. You flashed corrupted BIOS (badly downloaded - some BIOSes are not zipped on their home page - you can be never sure, if you downloaded them correctly). You flashed BIOS that is not for your motherboard. You got CIH or some similar virus that can destroy Flash ROM content (and you have motherboard that is "supported" by the virus).

There are three (at least) possible solutions:

• Use external Flash ROM programming device (if you have one) or find somebody which has one.
  Remove the Flash ROM chip from your motherboard, put it in the device and flash the correct BIOS image in.
• Have the Flash ROM reflashed by a re-programming service:
  http://www.flashbios.org
• Use Hot-Flash method.
  You need another motherboard which supports Flash ROMs and is supported by UniFlash. The chip you want to fix must be supported by UniFlash. Remove Flash ROM chip from the working motherboard. Put it back again, but don't push the chip, just place it gently in the socket so the pins make contact. Power it on and boot into pure DOS (or Win9x Safe Mode Command Prompt Only). Now carefully remove the Flash ROM chip (motherboard is still powered on at DOS prompt). Motherboard should work normally (try typing something at the DOS prompt to make sure it's alive and not frozen). Now place the bad chip in the socket and launch UniFlash. It should identify the chip correctly. Flash the correct BIOS image in (go into Advanced submenu and flash including bootblock). Then power down the system and put both chips back to their motherboards.
  
  If the UniFlash hangs during flashing or can't identify the chip correctly, it's possible that the chip itself is faulty (or there's a bug in UniFlash or the voltages are not correct - see below). In this case, you need to buy the same chip and flash the required BIOS in (using the same method).

  Some 12V Flash ROMs require 12V voltage not only to flash, but also to detect (for example Macronix MX28F1000P).

  If you're trying to flash 12V chip, first check that you have 12V on the VPP pin in the socket on motherboard (using voltmeter). Flash write protect jumper usually removes 12V from this pin.
  When some parts of the chip are write protected, 12V on VPP/RESET pin will usually allow these protected parts to be flashed.
  
  Be sure that Flash ROM is inserted the correct way in the socket (key on the chip must match with key on the socket) BEFORE powering up (if you're hot-flashing, double check chip orientation before inserting it into socket).

  Inserting it wrong way will DESTROY the chip - VCC will be swapped with GND and if there's 12V on the VPP pin, it will be connected to Q3 data pin...

  Flash ROM pinout (32-pin DIP), view from top:

  VPP = Programming voltage (12V) VCC = Operating voltage (5V) GND = Ground A0..A17 = Address input pins Q0..Q7 = Data input/output pins WE = Write enable OE = Output enable CE = Chip enable

  Notes: some chips have RESET instead of VPP this is 256KB chip 512KB chips have A18 instead of VPP 128KB chips have NC instead of A17 64KB chips have NC instead of A17 & A16

  
  If your chip needs 12V on the VPP pin, but 12V isn't there and write protect jumpers (if any) are set properly on the motherboard, you can make simple "adapter", which will connect 12V to the VPP pin. You will need 32-pin socket and cable from old CPU fan (a piece of wire will do the same job).
  
  

  First, turn the socket upside down. Cut the VPP pin off and solder the red wire there. Then you must isolate the solder point, so it can't accidentally connect with the VPP/RESET signal from motherboard (it will damage your motherboard otherwise!) I put some glue there. Then insert the chip into this socket. You can then use regular hot-flash method (see above). Swap the chips only when the cable is NOT connected to power supply. Connect it only AFTER the chip with socket is inserted in the socket of motherboard!

  
  Please note that the socket is turned upside-down on the image above! Make sure you connected 12V to the correct pin VPP!

You can have a look at BIOS Forum at Wim's BIOS Page: http://www.wimsbios.com/phpBB2/.

AMI Flash Utility v8.15.02

This program is very buggy, large and slow, but it can do VERY interesting thing - overwrite the boot block in Winbond W29C020C Flash ROM even when the chip's built-in boot-block write protection is enabled! I downloaded it from PC Chips home page about a year ago.