STACK MECHANISM HAVING MULTIPLE DISPLAY REGISTERS

• Main Authors: BOBBY A. CREECH, BENJAMIN A. DENT, WILLIAM M. MCKEEMAN, ROBERT S. BARTON
• Format: Patent
• Language: English
• Published: 12.08.1969
• Subjects: CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; INFORMATION STORAGE; PHYSICS; STATIC STORES

1,233,927. Data processing. BURROUGHS CORP. 30 Sept., 1968 [2 Oct., 1967], No. 46292/68. Heading G4A. A data processing system comprises an addressable memory containing a stack of information items linkable to a last in, first out stack implementation for processing, the stack having a plurality of stack areas of sequentially addressable memory locations each area having a mark word at its base which points to another mark word in the stack thereby linking the stack areas together in a tree-structured address environment, an information item below the top of the stack being selectable by combining an index value with the absolute address of a mark word, the absolute address being obtained from one of a plurality of display registers selected by a level value. Besides the registers two other groups of addressable registers (all utilizing transistor flip-flops) are provided, the addresses of the top and bottom of the stack in memory being specified by respective registers in the other groups. Each mark word is at the bottom of a portion of the stack used as local storage for a respective ALGOL programme block. Two further registers (not in any of the three groups) can act as the top locations of the stack. A third further register can receive an "indirect reference word" which provides the index value and also selects one of the display registers, the contents of which are stored in the registers of the second group (this step may be omitted) then added to the index value to address the memory to get a variable or parameter which is inserted in the third further register. The mark words link the stack portions according to a stack history list and an address environment list, the latter expressing which ALGOL blocks are contained within which in the programme.