On Mon, Jun 1, 2009 at 3:49 PM, Arthur Evans <aceevans_95 at hotmail.com> wrote: The BIOS battery in a Compaq SLT/286 is embedded inside the Dallas DS1287 clock module. The battery itself is +3V, but you replace the entire module, chip _and_ battery in one go. This is entirely unlike "modern" PCs where you have a Lithium coin cell (CR2032, typically) accessible and easy to replace. It's easy to find discussions of this particular machine. Here's one... <http://www.vintage-computer.com/vcforum/showthread.php?p=91535> Physically, the DS1287 is located in the middle of the board, under the battery tray, but you have to dismantle the entire machine to get to it. Also, it's soldered in place. To make it harder, there's not enough vertical clearance to install a socket. I installed a low-profile socket in mine, but had to nibble a hole in the battery tray to make room for the replacement Dallas clock. It is not a trivial procedure to replace the DS1287 in a Compaq SLT/286, certainly not compared to popping a coin cell out and in. -ethan