When I used $random(seed) the seed value also changing for repeated calls.
But for $urandom(seed) why seed value is not changing. I am using questasim 6.2b.
See the program below.
module Tb();
integer numr,numu,seedr,seedu,i,j;
initial
begin
seedr = 2;seedu = 2;numr = 10;numu = 10;
for(j = 0;j<2 ;j=j+1)
begin
$display(" seed for urandom = %d seed for random = %d ",seedu,seedr);
for(i = 0;i < 6; i=i+1)
begin
$display("Iteration %d",i);
numu =  $urandom(seedu)  % 10;
numr =  $random(seedr)  % 10;
$write("| seed(urandom) = %2d num(urandom)=%2d \nseed(random) = %2d num(random)=%2d |\n",seedu,numu,seedr,numr);
end
display(" ");
end
end
endmodule
OUTPUT:
#  seed for urandom =           2 seed for random =           2
# Iteration           0
# | seed(urandom) =  2 num(urandom)= 7
# seed(random) = 138139 num(random)=-8 |
# Iteration           1
# | seed(urandom) =  2 num(urandom)= 7
# seed(random) = 951188000 num(random)=-5 |
# Iteration           2
# | seed(urandom) =  2 num(urandom)= 7
# seed(random) = 1784212385 num(random)=-6 |
# Iteration           3
# | seed(urandom) =  2 num(urandom)= 7
# seed(random) = -1731404562 num(random)= 5 |
# Iteration           4
# | seed(urandom) =  2 num(urandom)= 7
# seed(random) = -1607270249 num(random)= 0 |
# Iteration           5
# | seed(urandom) =  2 num(urandom)= 7
# seed(random) = -529128468 num(random)= 8 |