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Burroughs' B Series Systems. E. A. Hauck B. A. Dent Presenter: Yi Ma and Hongliang Gao. The Objectives. - PowerPoint PPT Presentation
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Computer Science DepartmentUniversity of Central Florida
Burroughs' B Series Systems
E. A. Hauck B. A. DentPresenter: Yi Ma and Hongliang Gao
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The ObjectivesThe Objectives
• The basic objective in designing the system was to define a complete system, both hardware and software together, to enable programs written in high level languages to be compiled and run efficiently.
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Main Features
• Important features:– Dynamic storage allocation– Reentrant programming– Recursive procedure facilities– A tree structured stack organization– Memory protection– An efficient interrupt system
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ContentsContents
• The Objectives• Main Features• B6500/B7500 Processor• The Stack• Data Addressing• Non-local Addressing• Multiple Stacks and Re-Entrant Code• The Operating System• Summary
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B6500/B7500 Processor
• Basic machine instruction: operator syllable– 8 bits to a maximum of 96 bits
• Hardware implemented stack• Data word
– 51 bits (3 bits tag + 48 bits data)– Tag: data/operator, memory protection
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The StackThe Stack
Stack memory area
WORD ntx
Stack area assigned to
program
WORDn
TOS WORD
Stack area currently in
use
Stack limit register
SL (Stack Limit)
BOS (Base of Stack)
A
B
X
Y S
Top of stack registerIN/OUTPUT Path of data
to stack
Fast. Can hold two operands.
If double precision, A+X & B+Y.
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Data AddressingData Addressing
• Three mechanisms:– Data Descriptor (DD)/ Segment Descriptor (SD),
• Addresses which are located outside of the job's stack area.
• Absolute machine address.– Indirect Reference Word (IRW),
• Relative address• Address within the immediate environment of the
job's stack– Stuffed Indirect Reference Word (IRWS).
• Relative address• Beyond the immediate environment of the
current procedure
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Non-Local AddressingNon-Local Addressing
• Facility for storing the dynamic history of a program under execution– Stack history list – Addressing environment list
• Mark Stack Control Words (MSCW)
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Non-Local Addressing
MSCW DF
Outer program block
MSCW DF
Procedure ‘C’
MSCW DF
Procedure ‘D’
MSCW DF
Procedure ‘A’
TOS WORD
MSCW DF
Procedure ‘B’
S
F Stack history list
The program{A{
B{} B;
}C{ real v4; D{
A; } D;
} C;}
• Procedures are entering …
• Procedure B exits.• Non-Local Addressing Problem
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Non-Local Addressing cont.
• Address Couple:– The
lexicographical level
– The index
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Non-Local Addressing cont.
MSCW
TOS WORD
MSCW
MSCW
MSCW
MSCW
DISP DF
DISP DF
DISP DF
DISP DF
DISP DF
Outer program block
Procedure ‘C’
Procedure ‘D’
Procedure ‘A’
Procedure ‘B’
S
FStack history list
D0
D1
D2
D3
D4
D31
Display registers
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Multiple Stacks and Re-Entrant CodeMultiple Stacks and Re-Entrant Code
• Code sharing
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The Operating SystemThe Operating System
• The operation of the system was to be directed by a Master Control Program (MCP)
• Supports multiprogramming• 40 interrupt conditions (including timing interrupt)
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SummarySummary
• Hardware:– Multiple Stacks
• Programming:– Be done in ALGOL and COBOL
• Main features:– Dynamic storage allocation– Reentrant programming– Recursive procedure facilities– A tree structured stack organization– Memory protection– An efficient interrupt system
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ReferencesReferences
1. “Burroughs’ B6500/B7500 Stack Mechanism”, E. A. Hauck and B. A. Dent, Chapter 16 of Computer Structures: Principles and Examples, McGraw-Hill, 1982
2. “Operating System For The B 5000”, C. Oliphint, 1964
3. “Studies In Operating Systems”, R. M. McKeag and R. Wilson, Academic Press, 1976
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Thank you!
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