Abstract: A memory exhaustion condition is handled in a data processing system having first and second regions of physical memory. The memory exhaustion condition is detected while the second region is mirroring at least part of the first region. In response to the memory exhaustion condition, memory mirroring is at least partially deactivated and at least part of the second region is utilized to augment the first region, such that the memory exhaustion condition is eliminated. In an illustrative embodiment, the data processing system compresses real memory into the first region of physical memory, and the memory exhaustion condition arises when the first region lacks sufficient available capacity to accommodate current requirements for real memory. The memory exhaustion condition is eliminated by compressing at least part of the real memory into the second region.

Abstract: An extended PCI bus (100) accepts both standard 33 MHz (101-102) and extended 66 MHz (103-104) PCI I/O devices, and permits the intermixing and interoperability of both types of devices on the same bus. Each extended 66 MHz initiator device (103) includes a target memory (205) that is programmed at boot up to include a list of address ranges of all extended 66 MHz devices. Each extended 66 MHz device includes a clock multiplier (202) that generates an internal 66 MHz clock signal by doubling the 33 MHz bus clock frequency. This clock multiplier may be in the form of a simple edge detecting frequency doubler (FIG. 4), or a phase locked loop (FIG. 5) that can also provide for phase adjustments to alter the skew between the bus and internal clocks. To transfer data between two extended 66 MHz devices, an extended initiator device sends, during the address/control phase of the bus cycle, a fast read or write command to the extended target device over the C/BE lines of the bus.