Abstract: A distributed directory structure and method are provided for writing directory information for compressed data on a direct access storage device (DASD). DASD includes a plurality of compression groups for storing compressed data. A micro directory table is written within each of the compression groups for the corresponding compressed data in the compression group. Compressed data and a directory update are written with a single write operation. A macro directory table is written in one area of the DASD. The macro directory table includes directory information used for translating a logical address to a physical base address for each compression group. The micro directory table includes directory information used for translating a logical address for a requested data page to a physical page address and page length within the compression group.

Abstract: With a 370 processing system, such as an IBM Entry Level System 9371, multiple IBM 3151 ASCII Display Stations can be attached with a plurality of I/O processors. A Local Copy Manager is provided for each of the I/O processors to execute. The microcode embodiment emulates a single 3274 Control Unit with a display station attached. Each I/O processor executes the unique Local Copy microcode and intercepts all print keys from each display station, captures the terminal's screen data, and interrupts the 370 processor with a request for service. There may be multiple printers defined. Printing of a hard copy of the screen is output of an operator defined printer demand.

Abstract: The performance of a multi-microprocessor implemented data processing system that emulates a mainframe system is enhanced and optimized in view of space and power constraints for purposes of address translation by providing RAM-based storage means of predetermined depth and width to function as a page address table. The storage means depth is set to at least provide bit space to represent the total number of fixed size pages possible in a given virtual memory space. The width of the storage means is set to at least provide bit space to represent the largest page number that might be encountered in the available real memory and to accommodate a predetermined number of bits that flag information pertinent to translation and system performance. Circuit means, including microcode, is provided for initializing and updating the contents of the storage means as required.