When it launched in 1992, the McLaren F1 was the most technologically sophisticated road car ever made. It was also the fastest, with a top speed of 240mph, and is now becoming one of the most expensive, with the value of each example surging from £640,000 when new to almost £10m today.

But the modern design, revolutionary three-seat layout and blistering performance can only be kept road-worthy with the helping hand of an enormous, slow, 20-year-old Compaq laptop computer. Running MS-DOS and with a thickness measuring in inches instead of millimetres, the Compaq LTE 5280 is usually worth just £200, yet it is vital to keep the 100 surviving F1 cars running.

As discovered by car blog Jalopnik on a trip to the McLaren headquarters in Woking, Surrey, the company's own Compaq 5280s feature a custom CA (conditional access) card that only the F1's onboard computer can talk to.

An employee at McLaren Special Operations, the division that helps keep the F1 roadworthy, explained: "The reason we need those specific Compaq laptops is that they run a bespoke CA card that is installed into them."

All F1s left on the road are shipped back to Woking each time they need a service or repair work, and whenever the owner decides they fancy a change to the paint, wheels and interior, or they want parts, like the lights, upgrading to modern standards. The Compaq laptops are dragged out of storage each time an engineer needs to talk to the car's onboard computer.

Compaq LTE 5280
This Compaq LTE 5280 is currently listed on eBay with a buy-it-now price of £218 eBay/Seller: Debiasnz

This constant use is causing the old Compaqs to struggle, and the company is now looking at a 21-century alternative. As the MSo worker said: "We are currently working on a new interface which will be compatible with modern laptops as the old Compaqs are getting less and less reliable and harder to find."

What must have felt like cutting-edge technology 25 years ago now looks like something from the storage cupboard of a science museum. But as technology continues to evolve (and cars become ever more technologically complex and advanced) there could well be a point 25 years from now when engineers dig out an old, dusty Mac Pro to service one of the first autonomous cars in a scene that will likely seem as quaint as McLaren's old Compaq.