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:
Also, HP Zbooks are in Space - https://www8.hp.com/us/en/campaigns/mars/index.html
For several years now the HP ZBook-15 Generation 2 has been the predominant model in use on the ISS. HP is up to Generation 8 for the ZBook now, so you can see that NASA gets a lot of mileage (literally!) out of a model once it's been selected.
There are surprisingly few modifications needed to suit the environment in which they use these laptops. For the most part, these are very similar to high-end laptops you can purchase for personal or corporate use.
Multiple operating systems are used on these machines. Probably not too surprising, the two most prevalent are Windows and Linux.
Here's a picture (credit NASA) of astronaut Jessica Meir at the robotics workstation where you can see 5 ZBook laptops in use, in addition to the dedicated robotics displays.