# Algorithmic State Machines - Oakland University Sequencing and Control Mano and Kime Sections 8-1 8-7 Sequencing and Control

Algorithmic State Machines Binary Multiplier Hardwired Control

Binary Multiplier VHDL Microprogrammed Control Algorithmic State Machine ASM Block

Timing Sequencing and Control

Algorithmic State Machines Binary Multiplier Hardwired Control Binary Multiplier VHDL Microprogrammed Control

An Algorithmic Binary Multiplier Either adding the multiplier or 0000 Shifting partial product right

is the same as shifting the multiplier to the left If GO Then Initialize the multiplier Begin in state MUL0

If the right-most bit of the multiplier in the Q shift register is 0 then goto state MUL1 Otherwise, if the right-most bit of the multiplier is 1 then

add the partial product (A) to the multiplicand (B) and store it in A. Prepare to shift in C. Shift a 0 into C, shift right C || A || Q into C || A || Q Decrement P

C || A || Q denotes a composite register. If Z = 1 then we have gone through the state machine n -1 times and we are finished

Otherwise, if Z = 0 we continue back to state MUL0. Register A contains the four most significant bits of the product and Register Q contains the four least significant bits of

the product when we are finished. Note that n-bits x n-bits <= 2n bits Sequencing and Control

Algorithmic State Machines Binary Multiplier Hardwired Control Binary Multiplier VHDL

Microprogrammed Control Lets take a closer look at the control unit Sequencing State Machine

Decoder outputs based off of the present state --The decoder plays role in controlling the next state 00 01

10 ASM chart transformation rules with one flip-flop per state Notice two flip flops for

the two states, MUL0 and MUL1 Idle Junction (from Z and G) Idle State Decision Box

junction State MUL0 State MUL1 Z Decision Box Sequencing and Control

Algorithmic State Machines Binary Multiplier

Hardwired Control Binary Multiplier VHDL Microprogrammed Control VHDL -- Binary Multiplier with n=4; VHDL Description library ieee;

use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity binary_multiplier is port(CLK, RESET, G, LOADB, LOADQ: in std_logic; MULT_IN: in std_logic_vector(3 downto 0); MULT_OUT: out std_logic_vector(7 downto 0)); end binary_multiplier;

architecture behavior_4 of binary_multiplier is type state_type is (IDLE, MUL0, MUL1); signal state, next_state : state_type; signal A, B, Q: std_logic_vector(3 downto 0); signal P : std_logic_vector(1 downto 0); signal C, Z: std_logic;

begin Z <= (P1) NOR P(0); MULT_OUT <= A & Q; State Machine state_register: process (CLK, RESET)

begin if (RESET = 1) then state <= IDLE; elsif (CLKevent and CLK = 1) then state <= next_state; end if; end process;

next_state_func: process (G, Z, state) begin case state is when IDLE => if G = 1 then next_state <= MUL0;

else next_state <= IDLE; end if; when MUL0 => next_state <= MUL1; when MUL1 => if Z = 1 then

next_state <= IDLE; else next_state <= MUL0; end if; end case; end process;

Next State DATAPATH datapath_func: process (CLK) variable CA: std_logic_vector(4 downto 0); begin if (CLKevent and CLK = 1) then

if LOADB = 1 then B <= MULT_IN; when MUL1 => end if; C <= 0; if LOADQ = 1 then A <= C & A(3 downto 1);

Q <= MULT_IN; Q <= A(0) & Q(3 downto 1); end if; P <= P - 01; case state is end case; when IDLE =>

end if; if G = 1 then end process; C <= 0; end behavior_4; A <= 0000; P <= 11;

end if; when MUL0 => if Q(0) = 1 then CA := (0 & A) + (0 & B); else CA := C & A; end if;

C <= CA(4); A <= CA(3 downto 0); Sequencing and Control

Algorithmic State Machines Binary Multiplier Hardwired Control Binary Multiplier VHDL

Microprogrammed Control In general Microprogrammed Control Unit Organization Addresses lookup table

Acts like a control output lookup table Note 5 states Basic ASM Chart from initial design

ASM Chart for microprogrammed Control Unit What do we store in our lookup ROM? Next state (1 or 5) A Micro-instruction Control Word

Control Signals With this in mind, we need to design the control words... Use two next_addresses

Microprogrammed Control Unit for Multiplier