Abstract: An apparatus for rapidly updating a target display buffer memory from a source display buffer memory using a communication subsystem includes an element for associating a region number and an update indicator with each of a plurality of data-containing regions in the source display buffer memory. As display elements in the source display buffer memory are modified, the corresponding update indicator is modified. An update monitoring element periodically examines the update indicators of all regions. A transmitting element transmits the modified regions over the communication subsystem to corresponding regions within the target display buffer memory. The update indicators for the transmitted regions are further modified to indicate that the corresponding region of the source display buffer memory has been copied.

Abstract: The invention comprises a combined hardware and software method and apparatus for determining the size of memory located on a memory card inserted in the slot of a memory backplane of a computer system. The method and apparatus also provides a means for selecting the memory card which contains a requested memory location. Each memory slot has associated therewith a multibit code which indicates the size of the memory installed in the associated slot. The code from each slot is hardwired to the system memory controller which, given the codes can, as part of its memory initialization route, scan these bits and decode them in order to determine the amount of memory installed in each slot of the memory backplane.Each slot is further provided with an X-bit starting address which uniquely defines the lowest address available from the board inserted in the associated slot. The starting address from each slot is compared with the leftmost X-bits of the currently requested memory address.