ISA Storage Architecture

Abstract

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• Defines the way how a computer system manages and accesses data storage

Important

Accumulator ISA and Stack ISA use implicit operands.

The implicit operand in Stack-based architecture is “top-of-the-stack” whereas in accumulator-based architecture it is a special register called an accumulator.

Accumulator ISA

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1. load A: Load value from Main Memory into accumulator which is a special Register!
2. add B: Add value from Main Memory and value in the accumulator. The sum is stored back to the accumulator
3. store C: Store value in accumulator into Main Memory

Load-Store ISA

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• Also known as Register-Register ISA
• The data is decoupled from the Register to Main Memory

Data Loading

Can only load data at Word boundaries.

Memory-Memory ISA

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Stack ISA

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1. push A, push B: We load values from Main Memory onto the Stack
2. add: Remove the top 2 values in the Stack, add them, and load the sum onto top of Stack
3. pop C: Transfer value at top of Stack to Main Memory