Abusing copyright strings to trick software into thinking it's running on your competitor's PC

Summary

The Windows 95 team used clever tricks to retrofit Plug and Play onto legacy hardware, gathering information from a wide range of PC brands and models to identify them. One such trick involved finding copyright strings in the BIOS, such as "Not Copyright Fabrikam Computer." This string was theorized to be used by Contoso PCs to trick software into unlocking features of preinstalled trial software, despite not being a Fabrikam PC.

Convoluted Retrofitting Techniques

Retrofitting Plug and Play onto legacy hardware required complex techniques to signal information without confusing existing hardware. For example, the serial port detection sequence involved specific values written to the ADDRESS port to enter configuration mode, and then reading values from the READ_DATA port based on device responses. Devices had to coordinate responses to avoid conflicts, with the cycle repeating until all devices were identified.