How to replace the internal clock battery
How to replace the internal clock battery ?
Released in June of 2009, the 1005HA is identified by its "Seashell" design, and is available in many different varieties in regards to operating system, internal storage, and battery size.
BTW, you might want to know before you open the case that the battery you are replacing is labeled "ML1220/2E2E0X", which is a small watch-style cmos button battery soldered to a wire pigtail, so it's ready to plug in.
Another option is un-solder the original, find a generic ML1220 battery, and then solder the old pigtail connector to it, using shrink-wrap tubing to seal things back up.
[This battery is probably identical to the very common CR1220, both being 3V lithium button batteries. Dunno. Switch to a different model if you don't mind the uncertainty and risk.]