The document discusses Flynn's taxonomy for classifying computer architectures based on the number of instruction streams and data streams. It describes the four classifications: SISD (single instruction, single data), SIMD (single instruction, multiple data), MISD (multiple instruction, single data), and MIMD (multiple instruction, multiple data). SISD refers to classical von Neumann architectures that execute one instruction on individual data sequentially. SIMD executes a single instruction on multiple data values in parallel using multiple processors. MIMD allows different programs to execute different instructions on different data simultaneously using multiple processors.

1. Flynn’s Classification
UNIT-5
Hamidul Islam
Roll-1654510006
2nd year , CSE branch
JET, Barabanki
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2. Flynn’s Classification of Computer
Architecture
 In 1996, Michel Flynn proposed a classification for computer architectures
based on the number of instruction steams and data steams (Flynn’s
Taxonomy).
 Flynn’s uses the steam concept for describing a machine’s structures.
 A steam simply means a sequence of items (data or instructions).
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3. Flynn’s Taxonomy
 SISD: Single Instruction Single Data
---Classical von Neuman Architecture
 SIMD: Single Instruction Multiple Data
 MISD: Multiple instruction Single Data
---Non existent, just listed for completenes
 MIMD: Multiple Instruction Multiple Data
---Most common and general parallel machine
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4. Data Stream
Instruction Signal
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5. SISD
Control Unit tProcessors Memory
IS DS
IS
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6. SISD
 SISD machines executes a signal instruction on individual data
values using a single processor.
 Instructions are executed sequentially or serially, one step
after the next.
 Until most recently, most computers are of SISD type.
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7. SIMD
Control Unit
Processor
Processor
Memory
IS
DS
DS
IS
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8. SIMD
 An SIMD machine executes a single instruction on multiple data values
using many processors.
 SIMD architectures include array processors.
 Instruction but on different set of data; hence the name SIMD.
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9. MIMD
Control
unit
Control
unit
Processor
Processor
Memo
ry
IS
IS
IS
DS
DS
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10. MIMD
 The MIMD processors can execute different programs on different
processor.
 An instruction steam is generated from each program.
 Each instructions operates on different data.
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11. MISD
Control
unit
Control
unit
Processor
Processor
Memo
ry
IS
IS
IS
DS
DS
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12. MISD
 Multiple processor operates on different instructions but use same data
that’s why it is called Multiple instructions over single data.
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13. Analogy of Flynn’s Classifications
 An analogy of Flynn’s classification is the check-in desk at an airport.
SISD: a single desk
SIMD: Many desk and a supervisor with a megaphone giving
instructions that every desk obey.
MIMD: Many desk working at their own pace, synchronized
through a central database.
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14. .....................................................
THANK YOU!
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