What is the difference between Instructions decode and register fetch?

Answer 1

Instruction Register is where the instruction bit pattern is loaded for execution. Instruction Decoder is all the hardware logic that is cascade triggered by the instruction bit pattern during execution.

Answer 2

Instruction register is use to store the next instruction to be executed.

Instruction decoder is use to decode the instruction come from the memory and tell the CPU what is instruction really are. (CPU interpret instruction is different from the data store in the memory . A good example is , memory can store hexadecimal, but device only can read binary data.) without decoder the device cannot indicate or recognize the data )

Distinction

"memory can store hexadecimal, but device only can read binary data" This is an improperly worded, misleading statement. The difference between binary and hexadecimal is purely interpretive. Reading hexadecimal is a function of dividing the bits into groups of 4 and assigning a unique symbol to the pattern; 0-9 + A-F. This is only translating from one numbering system to another. The memory isn't specifically able to store hexadecimal as opposed to binary; it stores a BYTE as a group of EIGHT BITS no matter what. So even if the hardware is designed to move 64 bits at a time, grouping the bits into nibbles of four bits is how we interpret the bit pattern in hexadecimal.

Another Answer <<< Truth!

Instruction Register is where the instruction bit pattern is loaded for execution. Instruction Decoder is all the hardware logic that is cascade triggered by the instruction bit pattern during execution.

Answer 3

Instruction decode is the process after the register fetch.

Fetch--Store internal memory as register.

Decode- To make sense of the instruction which has just fetched