Reading-Comprehension
October 28, 2024Data-Interpretation
October 28, 2024Computer-Organization
| Question 20 |
A processor has 64 registers and uses 16-bit instruction format. It has two types of instructions: I-type and R-type. Each I-type instruction contains an opcode, a register name, and a 4-bit immediate value. Each R-type instruction contains an opcode and two register names. If there are 8 distinct I-type opcodes, then the maximum number of distinct R-type opcodes is _____.
| 14 |
All possible binary combinations = 216
There are 64 registers, so no. of bits needed to identify a register = 6
I-type instruction has (Opcode+Register+4-bit immediate value). There are 8 distinct I-type instructions.
All the binary combinations possible with the I-type instructions are = 8*26*24 = 213
R-type instructions have 2 register operands.
Let x be the number of R-type instructions.
All the possible binary combinations of R-type instructions = x*26*26 = x*212
The sum of I-type and R-type binary combinations should be equal to 216.
x*212 + 213 = 216
212 (x+2) = 216
x+2 = 24
x = 16 – 2 = 14
All possible binary combinations = 216
There are 64 registers, so no. of bits needed to identify a register = 6
I-type instruction has (Opcode+Register+4-bit immediate value). There are 8 distinct I-type instructions.
All the binary combinations possible with the I-type instructions are = 8*26*24 = 213
R-type instructions have 2 register operands.
Let x be the number of R-type instructions.
All the possible binary combinations of R-type instructions = x*26*26 = x*212
The sum of I-type and R-type binary combinations should be equal to 216.
x*212 + 213 = 216
212 (x+2) = 216
x+2 = 24
x = 16 – 2 = 14