The PC7457 is the fourth implementation of the fourth generation (G4) microprocessors from Motorola. The PC7457 implements the full PowerPC 32-bit architecture and is targeted at networking and computing systems applications. The PC7457 consists of a processor core, a 512 Kbyte L2, and an internal L3 tag and controller which support a glueless backside L3 cache through a dedicated high-bandwidth interface. The PC7447 is identical to the PC7457 except it does not support the L3 cache interface. The core is a high-performance superscalar design supporting a double-precision floating-point unit and a SIMD multimedia unit. The memory storage subsystem supports the MPX bus interface to main memory and other system resources. The L3 interface supports 1, 2, or 4M bytes of external SRAM for L3 cache and/or private memory data. For systems implementing 4M bytes of SRAM, a maximum of 2M bytes may be used as cache; the remaining 2M bytes must be private memory. Note that the PC7457 is a footprint-compatible, drop-in replacement in a PC7455 application if the core power supply is 1.3V.