AMD Barton

In February 2003, AMD introduced the first processor based on the new Athlon XP core, codenamed Barton. While this Athlon 3000+ chip had all the features of previous Athlon XP processors, the new core allowed it to boast a more efficient memory design than any previous Athlon processor. This was because the Barton combined the full-speed Level 2 cache design of Thunderbird and its successors with the larger 512KB cache size of the original Athlon processors.

A consequence of the larger cache is a much larger die, now comprising 54.3 million transistors and measuring 101mm2. This represents a significant increase compared with the Thoroughbred’s 54.3 million transistors/84mm2. As a result, the manufacturing cost of the Barton is significantly greater than that of the predecessor core.

As well as its increased size, the Barton core also provides for faster access to main memory, the 133MHz clock multiplier and 266MHz (133 x 2) FSB used by most earlier Athlon XP CPUs being replaced by a 166MHz clock multiplier and 333MHz (166 x 2) FSB.

The net result is that the Athlon XP 3000+ is able to outperform the earlier Thoroughbred-based Athlon XP 2800+, despite having a slower clock speed (2.167GHz vs 2.250).

The advent of the Athlon 64 processor in the autumn of 2003 was to mean that the Barton core was relatively short-lived, the last Athlon XP being the 3200+ model, launched little more than three months after the Barton had first appeared.