In many videos of the ISS, you can see tethered laptops all over the place. Presumably these are heavily customised for space. What kinds of customisation do they need? Are they off-the-shelf laptops with customisations for space-worthiness or custom-built hardware? What OS do they run?
Astronauts interact with the onboard systems on ISS via laptops, categorized into the Portable Computer System (PCS) and Station Support Computer (SSC).
The firsts provide the interface with the ship’s computer systems while the others are used for office and personal tasks.
From the Lenovo blog (march 20, 2012)
• ThinkPad is the only laptop certified for use on the International Space Station (ISS).
• ThinkPads have been used aboard the International Space Station since 1998.
• ThinkPads have been on every NASA Shuttle space flight since 1995, when the ThinkPad 755 blasted off with the crew.
• ThinkPad laptops are used by all the major world space agencies (e.g., JAXA, ESA) thanks to their partnership with NASA.
• Some tests ThinkPads have to pass before they lift off: radiation testing, off-gas testing, thermal testing, fire & fire suppression.
• Number of ThinkPads aboard the International Space Station: more than 60.
• Number of NASA shuttle flights that have lifted off with ThinkPads aboard: more than 50.
and this link is about software: astronauts in future will use Debian 6 moving from Windows and Scientific Linux
If you wish more details you can read also: