Intel Pga478 Data Sheet - Page 34

Intel® Celeron® Processor 1.66 GHz/1.83 GHz-Package Mechanical Specifications and Pin Information Table 11. Signal Description (Sheet 5 of 7) Name IGNNE# INIT# LINT[1:0] LOCK# MCERR# ODTEN PRDY# PREQ# Type Input Input Input Input/ Output Input/ Output Input Output Input Description IGNNE# (Ignore Numeric Error) is asserted to force the processor to ignore a numeric error and continue to execute non-control floating-point instructions. If IGNNE# is deasserted, the processor generates an exception on a noncontrol floating-point instruction if a previous floating-point instruction caused an error. IGNNE# has no effect when the NE bit in control register 0 (CR0) is set. IGNNE# is an asynchronous signal. However, to ensure recognition of this signal following an Input/Output write instruction, it must be valid along with the TRDY# assertion of the corresponding Input/Output Write bus transaction. INIT# (Initialization), when asserted, resets integer registers inside the processor without affecting its internal caches or floating-point registers. The processor then begins execution at the power-on Reset vector configured during power-on configuration. The processor continues to handle snoop requests during INIT# assertion. INIT# is an asynchronous signal. However, to ensure recognition of this signal following an Input/Output Write instruction, it must be valid along with the TRDY# assertion of the corresponding Input/Output Write bus transaction. INIT# must connect the appropriate pins of both FSB agents. LINT[1:0] (Local APIC Interrupt) must connect the appropriate pins of all APIC Bus agents. When the APIC is disabled, the LINT0 signal becomes INTR, a maskable interrupt request signal, and LINT1 becomes NMI, a nonmaskable interrupt. INTR and NMI are backward compatible with the signals of those names on the Intel® Pentium® processor. Both signals are asynchronous. Both of these signals must be software configured via BIOS programming of the APIC register space to be used either as NMI/INTR or LINT[1:0]. Because the APIC is enabled by default after Reset, operation of these pins as LINT[1:0] is the default configuration. LOCK# indicates to the system that a transaction must occur atomically. This signal must connect the appropriate pins of both FSB agents. For a locked sequence of transactions, LOCK# is asserted from the beginning of the first transaction to the end of the last transaction. When the priority agent asserts BPRI# to arbitrate for ownership of the FSB, it waits until it observes LOCK# deasserted. This enables symmetric agents to retain ownership of the FSB throughout the bus locked operation and ensure the atomicity of lock. MCERR# (Machine Check Error) is asserted to indicate an unrecoverable error without a bus protocol violation. It may be driven by all processor front side bus agents. MCERR# assertion conditions are configurable at a system level. Assertion options are defined by the following options: • Enabled or disabled. • Asserted, if configured, for internal errors along with IERR#. • Asserted, if configured, by the request initiator of a bus transaction after it observes an error. • Asserted by any bus agent when it observes an error in a bus transaction. For more details regarding machine check architecture, refer to the Intel® 64 and IA-32 Architectures Software Developer's Manuals in Volume 3A/3B: System Programming Guide. Since multiple agents may drive this signal at the same time, MCERR# is a wireOR signal which must connect the appropriate pins of all processor front side bus agents. In order to avoid wire-OR glitches associated with simultaneous edge transitions driven by multiple drivers, MCERR# is activated on specific clock edges and sampled on specific clock edges. ODTEN (On-die termination enable) should be connected to VCC to enable on-die termination for end bus agents. Intel® Celeron® Processor 1.66 GHz/1.83 GHz is always the end bus agent because it supports uniprocessor configurations only. Whenever ODTEN is high, on-die termination is active, regardless of other states of the bus. Probe Ready signal used by debug tools to determine processor debug readiness. Probe Request signal used by debug tools to request debug operation of the processor. Intel® Celeron® Processor 1.66 GHz/1.83 GHz DS 34 January 2007 Order Number: 315876-002