$display, $displayb, $displayh, $displayo, $write, $writeb, $writeh, $writeo. 

The most useful of these is $display.This can be USED for displaying strings, expression or values of variables. 

Here are some examples of usage. 

$display("Hello oni");
--- output: Hello oni
$display($TIME) // current simulation time.
--- output: 460
counter = 4'b10;
$display(" The COUNT is %b", counter);
--- output: The count is 0010
$reset resets the simulation back to time 0; $stop halts the SIMULATOR and puts it in interactive mode where the user can enter commands; $finish exits the simulator back to the operating system

$display, $displayb, $displayh, $displayo, $write, $writeb, $writeh, $writeo. 

The most useful of these is $display.This can be used for displaying strings, expression or values of variables. 

Here are some examples of usage. 

$display("Hello oni");
--- output: Hello oni
$display($time) // current simulation time.
--- output: 460
counter = 4'b10;
$display(" The count is %b", counter);
--- output: The count is 0010
$reset resets the simulation back to time 0; $stop halts the simulator and puts it in interactive mode where the user can enter commands; $finish exits the simulator back to the operating system