Question

What is an ISA?

Research an ISA and write down the following details:

a.    What are some of the data types supported?

b.    What are the addressing modes?

c.    How long is an instruction in bits?

d.    Which ISA did you research?

Answer 1

An instruction set architecture (ISA) is an abstract model of a computer. It is also referred to as architecture or computer architecture. A realization of an ISA is called an implementation

A.Data types of IS A

32-bit IEEE single-precision floating-point
• 40-bit IEEE extended-precision floating-point
• 32-bit integers

B..    What are addressing modes.

Register direct R3
- Immediate (literal) #25
- Direct (absolute) M[10000]
- Register indirect M[R3]
- Base+Displacement M[R3 + 10000]

if register is the program counter, this is PC-relative
- Base+Index M[R3 + R4]
- Scaled Index M[R3 + R4*d + 10000]
- Autoincrement M[R3++]
- Autodecrement M[R3 --]
- Memory Indirect M[ M[R3] ]

C.How long is an instruction in bits

Variable-length instructions (Intel 80x86, VAX) require
multi-step fetch and decode, but allow for a much more
flexible and compact instruction set.
• Fixed-length instructions allow easy fetch and decode, and
simplify pipelining and parallelism.
All MIPS instructions are 32 bits long.
–this decision impacts every other ISA decision we make because it makes instruction bits scarce.

D.which ISA did you research?

I studied the isa for 8086.

Hope this will help