Abstract: In a data processor having a paging system, a list is kept of the disk seek time when a page of information is brought into processor memory from a disk storage device. (Seek time is the time for moving the disk read-write head radially inward or outward to the next track that is to be accessed.) The average seek time for the pages in memory is calculated and is compared with a reference value of seek time. When the average reaches the reference, the pages in memory are reordered on the disk. This reordering takes place as the pages are bumped from memory in the normal process of paging, and the pages are relocated on the disk tracks in the physical order in which the pages were originally brought into memory. If approximately the same pages are fetched again in approximately the same sequence, the read-write head of the disk drive will be moved a shorter distance between successive disk accesses with reduced backtracking.

Abstract: A reprogrammable plug-in semiconductor memory cartridge for use in a personal computer system, the cartridge being reprogrammed without removing the circuitry from the cartridge. The cartridge uses a keying-locking circuitry, such as a resistor-capacitor circuit having a unique time constant which must be detected by a cartridge programming system before allowing the programming operation to start. Thus access to a programming system program library is limited only to cartridges having the above-mentioned keying-locking circuitry. A cartridge retailer maintains a master program library and a limited number of such blank cartridges rather than maintaining a large inventory of programmed cartridges.