GATE Computer Science (CS) 2018 Shift 1 Solved Paper

Question : 63 of 65

Marks: +1, -0

A processor has 16 integer registers (R0, R1, …… R15) and 64 floating point registers (F0, F1, ……, F63). It uses a 2-byte instruction format. There are four categories of instructions. Type1, Type-2, Type-3 and Type-4. Type-1 category consists of four instructions, each with 3 integer register operands (3Rs). Type-2 category consists of eight instructions, each with 2 floating point register operands (2Fs). Type-3 category consists of fourteen instructions, each with one integer register operand and one floating point register operand (1R + 1F). Type-4 category consists of N instructions, each with a floating point register operand (1F). The maximum value of N is _________.

Your Answer:

Validate

Solution:

Instruction size = 16 bit
Type I instruction design :

Number of operations

2^16=16

Face opcodes

16-4=12

Type II instruction design:

Face opcodes after type 1 instruction = 12
Face opcodes after type 2 instruction

=12-8=4

Type III instruction design:

Expand opcode size 6 bit
Number of opcodes

2^4=16

∴ Number of free opcodes after type
3 instruction

16 -4= 2

Type IV instruction design :

Expand opcode size 10 bit
Number of opcodes

2×2^4=2^5=32

Go to Question:

Prev Question

Next Question