FDER cycle

I'm having trouble understanding what exactly happens in the decode and execute parts of the FDER cycle in a Von Neumann machine. I fully understand the fetch part of an instruction no problem...but would someone be kind enough as to explain to me what happens EXACTLY in the decode and execute part of the cycle ? including the use of registers where appropriate....im a little confused at what the textbook is telling me. Thanks in advance :smile:

Reply 1

teachercol

Decode means decoding the opcode part of the instruction. Is it an add or a subtract? How is the operand to be found? Is it indexed or indirected? Then the processor refers to a microrom inside which converts these to a series of microinstructions which are then executed.

Best book for getting a feel about processors : Soul of a new machine : T Kidder.