Starting out with the basics, the Radeon HD 2600 XT is based around AMD's 390 million transistor, 65 nanometre manufactured RV630 core, and is basically a shrunk and reduced version of the massive R600 core that powers the company's flagship Radeon HD 2900 XT part. Compared to the 320 shader processors which make up that high-end part, RV630 features 120 shader processing units, split into three arrays of forty processors (compared to four arrays of eighty in R600). The number of texture units and ROPs are also reduced compared to R600, to two and one respectively against four and four in AMD's flagship core. Finally, RV630 finds itself with a good old 128-bit memory bus, utilising a ring bus memory controller, compared to the 512-bit behemoth on R600. Some pretty hefty cuts there, particularly with regard to the ROP count - Of course, we'll see how that affects performance in due course.