LC-3 FSM . LC-3 Datapath . LC-3 Datapath Control Signals . cc figure +0P2 OP2 -NOT(SR MDR<-M MAR R7<-pc _pC+ To 49 ST -M 13 [BEN] PC & & Z. IR ARC MAR] MAR<-MDR —Base 18 18 I I 18 PC+0tt NOTES MAR] ARC MAR<-MDR 18 18 set CC 18 FC+0ffg pc SEXT{offsetg] : pc + SEXTIoffsA11 may be SR2 m z o N 0 0 70 0 0 70 70 3 0 70 o .

Simply check NZP flags with nzp from instruction to decide whether to ldPC or not Method 1: Could bring nzp flags into FSM as inputs and put comparison into state table... Bad idea.

LC3 Datapath –from Logic to Processor Data Path •The data path of a computer is all the logic used to process information. •Take all the devices we have discussed and use them to build a circuit that implements a von Neumann machine •Combinational Logic •Decoders --convert instructions into control signals

Each register load signal controls one or more registers. Each signal is set iff the RTL for the current FSM state changes that register’s value. In other words, the load signal is 1 if the register appears on the left side of an RTL expression, and is 0 …

Design the FSM using any hardware and optimize it. Large combinational blocks are usually designed using a PLA. Approach came back into vogue with RISC philosophy. Changing/adding design easier, was popular at a time. Modern processors use Verilog/VHDL specification automating part of the design.

Compute sum of 12 integers. Numbers start at location x3100.

We say that these 49 control signals specify the state of the control struc-ture of the LC-3 microarchitecture. We can completely describe the behavior of the LC-3 microarchitecture by means of a directed graph that consists of nodes (one corresponding to each state) and arcs (showing the flow from each state to the one[s] it goes to next).

How Does the LC-3 FSM Control Fetch and Decode? Let’s work out the control signals needed for instruction fetch and decode. The figure to the right is part of Patt and Patel Figure C.2. The first state: MAR ← PC, PC ← PC + 1 ECE 120: Introduction to Computing © 2016 Steven S. Lumetta. All rights reserved. slide 2 What are the Load Signals?

In this lab you will design the finite state machine controller for a subset of the LC3 instruc-tions. You will then link the controller to the Datapath from the last lab to form a complete CPU. You will then simulate the entire structure. The LC3 has 16 or so instructions. You will implement at least the AND, ADD, NOT,

Jun 8, 2020 · FSM turns on specific control signals in LC3, which activates certain paths in the datapath. The signals specify how data moves in the datapath to be used in operations like addition. The FSM fetches and decodes each instruction before executing the operation.