Answers.Body: <p>When you pass <code>movetime</code> to an engine via UCI, you're telling it to override any time management algorithms it might have, and to instead spend exactly <code>x</code> milliseconds analysing the position. </p>
  
  <p>When playing games, the UCI <code>movetime</code> parameter typically isn't specified. Instead, the engine is told how much time each player has left on their clock (and the increment, if any). This allows the engine to decide how much time to use with its own time management.</p>
  
  <p>The <code>Slow Mover</code> option is used to tell the engine how you would like it to manage time. It only means something in a game situation (i.e. when <code>movetime</code> isn't specified). Higher values will tell the engine, broadly, to use "more time", but it does not control the exact amount of time that is used.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-10-25T17:48:46.787Z
Answers.LastActivityDate: 2019-10-25T17:48:46.787Z
Answers.UserDisplayName: konsolas
Body: <p>When I tell the engine to find the best move with </p>
  
  <pre><code>go movetime 1 depth 1
  </code></pre>
  
  <p>I expect it allows itself to take up to about 1 ms to make it's move. But what's the difference between that and the <strong>Slow Mover</strong> option: </p>
  
  <pre><code>option name Slow Mover type spin default 84 min 10 max 1000
  </code></pre>
  
  <p>Looking at <a href="http://www.talkchess.com/forum3/viewtopic.php?t=42308" rel="nofollow noreferrer">this post from 2008</a> it seems like perhaps <strong>Slow Mover</strong> was implemented before the <strong>movetime</strong> option?</p>
  
Tags: <stockfish>
Title: What's the difference between movetime and the Slow Mover option?
ThreadText: # What's the difference between movetime and the Slow Mover option?
  
  (Asked by: username_0 on 2019-10-25)
  
  When I tell the engine to find the best move with 
  go movetime 1 depth 1
  
  I expect it allows itself to take up to about 1 ms to make it's move. But what's the difference between that and the Slow Mover option: 
  option name Slow Mover type spin default 84 min 10 max 1000
  
  Looking at this post from 2008 it seems like perhaps Slow Mover was implemented before the movetime option?
  
  **Tags:** stockfish
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2019-10-25. Score: 3 | Accepted answer
  
  When you pass `movetime` to an engine via UCI, you're telling it to override any time management algorithms it might have, and to instead spend exactly `x` milliseconds analysing the position.
  
  When playing games, the UCI `movetime` parameter typically isn't specified. Instead, the engine is told how much time each player has left on their clock (and the increment, if any). This allows the engine to decide how much time to use with its own time management.
  
  The `Slow Mover` option is used to tell the engine how you would like it to manage time. It only means something in a game situation (i.e. when `movetime` isn't specified). Higher values will tell the engine, broadly, to use "more time", but it does not control the exact amount of time that is used.
  
  
  ---
  
  