burroughs 1035441 B6500 B7500 Stack Mechanism 1968 free download

File name 1035441_B6500_B7500_Stack_Mechanism_1968.pdf

Reprintedfrom AFIPS ConferenceProceedings Volume 32, 1968 by E. A. HAUCK and B. A. DENT BurroughsCorporation Pasadena.California INTRODUCTION and within the Processor in 51 bit words. The first 3 bits of the word are used as tag bits, which serve to Burroughs' B6500/B7500 system structure and identify the various word types as illustrated in Fig. 1. philosophy are an extension of the concepts employed The remaining 48 bits are data. Tag bits, in addition in the development of the B5500 system. The unique to identifying word type, provide the 86500/87500 features, common to both hardware systems, are Processor with two unique features: (1) data may be that they have been designed to operate under the referenced as an operand, with the processor worrying control of an executive program (MCP) and are to about whether the operand consists of one or two be programmed in only higher level languages (e.g., words, and (2) system integrity and memory pro- ALGOL, COBOL, and FORTRAN). Through a tection are extended to the level of the basic machine close integration of the software and hardware dis- data words. If a job attempts to execute data as pro- ciplines, a machine organization has been developed gram code, or to modify program code, the system is which permits the compilation of efficient machine code and which is addressed to the solution of prob- interrupted. lems associated with multiprogramming, multiprocess- ing and time sharing. Some of the important features provided by the DATA WORDS 86500/B7500 system are dynamic storage allocation, I 000 Ii EXPONENT! MANTISSA I ~~~~{;ftECISION re-entrant programming, recursive procedure facili- ties, a tree structured stack organization, memory pro- I 0101 !IO EXPONENT