HP (Hewlett-Packard) 520 5/XX Personal Computer User Manual


 
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2 System Board - (SiS Chipset) (Part Number: D4051-63001)
Devices on the Processor Local Bus (D4051-63001)
The data cache tags (directory entries used to reference cached memory
pages) are triple-ported to support two data transfers and an inquire cycle
in the same clock cycle. The code cache tags are also triple-ported to
support snooping (a way of tracking accesses to main memory by other
devices) and split line accesses.
Individual pages of memory can be configured as cacheable or non-
cacheable by software or hardware. They can also be enabled and disabled
by hardware or software.
Data Integrity
The processor uses a number of techniques to maintain data integrity. It
employs two methods of error detection:
Data Parity Checking
This is supported on a byte-by-byte basis, generating parity bits for data
addresses sent out of the microprocessor. These parity bits are not used
by the external subsystems.
Internally
The processor uses functional redundancy checking to provide maximum
error detection of the processor and its interface.
Advanced Power Management
The Advanced Power Management (APM) is a standard, defined by Intel
and Microsoft, for a power-saving mode that is applicable under a wide
range of operating systems. The version APM 1.1 supports the following
modes: Fully-on, Standby, Suspend, and Off.
The Suspend mode is managed at the operating system level only, from the
Windows 95 Start menu. There is no longer the inter-activity between BIOS
Setup and operating systems, and no longer a “sleep at” item on the Setup
program menus, to avoid the BIOS from shutting down the system at the
wrong moment.