By 1997 the PowerPC 604e was getting a bit dated. Apple needed an updated faster processor for their new computers and IBM and Motorola needed a new processor to sell to Apple. The PowerPC 750 was an evolution of the 604e and became the core of Apple’s various G3 systems.
In early 1997 Apple , IBM, and Motorola (together known as the AIM Alliance) were working on what would become the PowerPC 750. It’s code name? The Arthur. Apparently someone at IBM or Motorola had a liking for Sherlock Holmes as the 745 was codenamed Conan and the 755 Doyle, after Sir Arthur Conan Doyle, writer of Sherlock Holmes. This particular part is date coded R20003PAP which means it was made in mid-May of 1997, 6 months before the G3 and PowerPC 750 were officially released.
The card the Arthur processor (hand labeled 300Mhz) resides on is an Apple Prototype known as the Goleta. The Goleta was one of the first Apple G3 products. It was to be used in the PowerMac 9700 aka the PowerExpress which was to be a 6 slot G3 PowerMac running at 275MHz.
It never made it past the prototype stage. The card is labeled as serial #014 making it a very early prototype, though how many total were made is not known. The card may have been used at Apple for testing other deigns as well and certainly was a test bench for the new 750 PowerPC Processor. This was a chaotic time for Apple as they were struggling to pull out of near bankruptcy. Steve Jobs had only just returned to the company and radically changed what Apple was doing, and what they were not doing (making money).