Intel 521 Data Sheet - Page 12

Introduction 1.1 1.1.1 The Pentium 4 processor on 90 nm process in the LGA775-land package will also include the Execute Disable Bit capability previously available in Intel® Itanium® processors. This feature combined with a support operating system allows memory to be marked as executable or nonexecutable. If code attempts to run in non-executable memory the processor raises an error to the operating system. This feature can prevent some classes of viruses or worms that exploit buffer overrun vulnerabilities and can thus help improve the overall security of the system. See the Intel® Architecture Software Developer's Manual for more detailed information. Intel will enable support components for the processor including heatsink, heatsink retention mechanism, and socket. Manufacturability is a high priority; hence, mechanical assembly may be completed from the top of the baseboard and should not require any special tooling. The processor includes an address bus powerdown capability that removes power from the address and data pins when the FSB is not in use. This feature is always enabled on the processor. Terminology A '#' symbol after a signal name refers to an active low signal, indicating a signal is in the active state when driven to a low level. For example, when RESET# is low, a reset has been requested. Conversely, when NMI is high, a nonmaskable interrupt has occurred. In the case of signals where the name does not imply an active state but describes part of a binary sequence (such as address or data), the '#' symbol implies that the signal is inverted. For example, D[3:0] = 'HLHL' refers to a hex 'A', and D[3:0]# = 'LHLH' also refers to a hex 'A' (H= High logic level, L= Low logic level). "FSB" refers to the interface between the processor and system core logic (a.k.a. the chipset components). The FSB is a multiprocessing interface to processors, memory, and I/O. Processor Packaging Terminology Commonly used terms are explained here for clarification: • Pentium 4 processor on 90 nm process in the 775-land package - Processor in the FC- LGA4 package with a 1-MB L2 cache. • Processor - For this document, the term processor is the generic form of the Pentium 4 processor in the 775-land package. • Keep-out zone - The area on or near the processor that system design can not use. • Intel 925X/915G/915P Express chipsets - Chipsets that supports DDR and DDR2 memory technology for the Pentium 4 processor in the 775-land package. • Processor core - Processor core die with integrated L2 cache. • FC-LGA4 package - The Pentium 4 processor in the 775-land package is available in a Flip- Chip Land Grid Array 4 package, consisting of a processor core mounted on a substrate with an integrated heat spreader (IHS). • LGA775 socket - The Pentium 4 processor in the 775-land package mates with the system board through a surface mount, 775-land, LGA socket. • Integrated heat spreader (IHS) -A component of the processor package used to enhance the thermal performance of the package. Component thermal solutions interface with the processor at the IHS surface. 12 Datasheet