The following recommended development system configuration can fully utilize the capabilities of the XDK and will provide the best experience. 1 GHz CPU 500 MB RAM 10 GB hard disk Windows XP SP1 ATI 3D accelerated video card, DX9-compatible, with 3.0 pixel shader and vertex shader support (when available) Ethernet network adapter Two USB 2.0 host controllers. Required when using DVD emulation and performance analysis tools simultaneously. For use with Xenon Beta consoles only (Alpha systems use Ethernet as the emulation transport). Firewire port. Required for kernel debugging. For use with Xenon Alpha systems only. The Xenon CPU is a custom IBM part based on the PowerPC architecture. It features three identical cores and a 1-MB L2 cache all on one chip. The main features of the Xenon CPU are: Three identical custom 64-bit PowerPC cores running at 3.5+ GHz Two hardware threads per core Two instructions per cycle per core 32-KB two-way 56+ GB/sec L1 instruction cache per core 32-KB four-way 56+ GB/sec L1 data cache per core Shared 1-MB eight-way 112+ GB/sec L2 cache on the same chip Direct read access to the L2 cache by the GPU 128-bit SIMD vector unit for float and integer operations Scalar floating-point unit, supporting float and double precision The following registers, one set for each thread on each core: 32 64-bit integer registers 32 64-bit floating-point registers 128 128-bit vector registers Instruction pointer, link register, count register, condition register, and so on 84+ GFLOPS total power (one vector multiply-add per core per cycle) Front side bus bandwidth of 10.8 GB/sec for reads, 10.8 GB/sec for writes Big-endian byte ordering Some of the resources, such as the registers, are per-thread resources, meaning there are six copies of them on the chip. Other resources—such as the L1 caches, vector unit, and scalar floating-point unit—are per-core resources, meaning that two hardware threads share each of them. Because the Xenon CPU is based on the PowerPC architecture, there are many sources of information for learning about this processor. A good starting point is the AltiVec PEM and PPC PEM documentation that ships with the Xenon Development Kit. Because there are many sources of generic PowerPC information, this paper concentrates on what makes the Xenon processor different from regular PowerPC processors. The main architectural difference between the Xenon CPU and the regular PowerPC processor—besides the three cores and the shared L2 cache on one chip—is the enhanced vector units, discussed in detail below. The integer unit and scalar floating-point unit are virtually unchanged from the PowerPC specification. The scalar floating-point unit includes these optional instructions: square root, reciprocal square root estimate, reciprocal estimate, and select. Storage The Xenon console is designed around a larger world view of storage than Xbox was. Games will have access to a variety of storage devices, including connected devices (memory units, USB storage) and remote devices (networked PCs, Xbox LiveTM). At the time of this writing, the decision to include a built-in hard disk in every Xenon console has not been made. If a hard disk is not included in every console, it will certainly be available as an integrated a Xenon supports up to two attached memory units (MUs). MUs are connected directly to the console, not to controllers as on Xbox. The initial size of the MUs is 64 MB, although larger MUs may be available in the future. MU throughput is expected to be around 8 MB/sec for reads and 1 MB/sec for writes. The Xenon game disc drive is a 12× DVD, with an expected outer edge throughput of 16+ MB/sec. Latency is expected to be in the neighborhood of 100 ms. The media format will be similar to Xbox, with approximately 6 GB of usable space on the disk. As on Xbox, media will be stored on a single side in two 3 GB layers. Industrial Design The Xenon industrial design process is well under way, but the final look of the box has not been determined. The Xenon console will be smaller than the Xbox console. The standard Xenon controller will have a look and feel similar to the Xbox controller. The primary changes are the removal of the Black and White buttons and the addition of shoulder buttons. The triggers, thumbsticks, D-pad, and primary buttons are essentially unchanged. The controller will support vibration