23 files changed, 183 insertions, 35 deletions

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b90b7de..5b3d31a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -97,7 +97,7 @@ jobs:
 
       - uses: hishamhm/gh-actions-luarocks@master
         with:
-          luaRocksVersion: "3.11.0"
+          luaRocksVersion: "3.12.0"
 
       - name: test dependencies
         run: |
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d4107d6..3b00fb6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,9 +27,20 @@ The scope of what is covered by the version number excludes:
 
 ## Version history
 
+### version 0.6.3, released 11-Jul-2025
+
+- Fix: maximum key-delay, reduced from 0.2 to 0.1 seconds to reduce slugginess feel on some key presses.
+  See [#69](https://github.com/lunarmodules/luasystem/pull/69).
+- Fix: `readansi` now only reports printable chars as characters
+  See [#70](https://github.com/lunarmodules/luasystem/pull/70).
+- Fix: readkey now ignores Windows scancodes if received.
+  See [#74](https://github.com/lunarmodules/luasystem/pull/74).
+- Fix: readkey now passes errors on.
+  See [#74](https://github.com/lunarmodules/luasystem/pull/74).
+
 ### version 0.6.2, released 15-Apr-2025
 
- - Fix: autotermrestore didn't work because its metatable was overwritten.
+- Fix: autotermrestore didn't work because its metatable was overwritten.
 
 ### version 0.6.1, released 13-Apr-2025
 
diff --git a/docs/classes/bitflags.html b/docs/classes/bitflags.html
index e11e39a..7637aeb 100644
--- a/docs/classes/bitflags.html
+++ b/docs/classes/bitflags.html
@@ -298,7 +298,7 @@ return <code>false</code> if the flags are checked.
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/compat.lua.html b/docs/examples/compat.lua.html
index ab4caab..ca4e489 100644
--- a/docs/examples/compat.lua.html
+++ b/docs/examples/compat.lua.html
@@ -112,7 +112,7 @@
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/flag_debugging.lua.html b/docs/examples/flag_debugging.lua.html
index 3fd5cd7..dba4471 100644
--- a/docs/examples/flag_debugging.lua.html
+++ b/docs/examples/flag_debugging.lua.html
@@ -80,7 +80,7 @@
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/password_input.lua.html b/docs/examples/password_input.lua.html
index 65d6e17..342b066 100644
--- a/docs/examples/password_input.lua.html
+++ b/docs/examples/password_input.lua.html
@@ -132,7 +132,7 @@ useful for reading secrets from the user.
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/read.lua.html b/docs/examples/read.lua.html
index 3e29b64..4995bda 100644
--- a/docs/examples/read.lua.html
+++ b/docs/examples/read.lua.html
@@ -143,7 +143,7 @@ sys.<span class="function-name">setnonblock</span>(<span class="global">io</span
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/readline.lua.html b/docs/examples/readline.lua.html
index 265021e..493de2c 100644
--- a/docs/examples/readline.lua.html
+++ b/docs/examples/readline.lua.html
@@ -549,7 +549,7 @@ sys.<span class="function-name">setconsoleflags</span>(<span class="global">io</
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/spinner.lua.html b/docs/examples/spinner.lua.html
index 6141dd5..6e2d63a 100644
--- a/docs/examples/spinner.lua.html
+++ b/docs/examples/spinner.lua.html
@@ -137,7 +137,7 @@ sys.<span class="function-name">setnonblock</span>(<span class="global">io</span
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/spiral_snake.lua.html b/docs/examples/spiral_snake.lua.html
index 8432fb1..97d5f77 100644
--- a/docs/examples/spiral_snake.lua.html
+++ b/docs/examples/spiral_snake.lua.html
@@ -145,7 +145,7 @@ codes for moving the cursor around.
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/examples/terminalsize.lua.html b/docs/examples/terminalsize.lua.html
index 610803b..d3486bb 100644
--- a/docs/examples/terminalsize.lua.html
+++ b/docs/examples/terminalsize.lua.html
@@ -110,7 +110,7 @@ sys.<span class="function-name">tcsetattr</span>(<span class="global">io</span>.
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/index.html b/docs/index.html
index a4446a7..e901d08 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -142,7 +142,7 @@
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/modules/system.html b/docs/modules/system.html
index 6840b85..0a2447e 100644
--- a/docs/modules/system.html
+++ b/docs/modules/system.html
@@ -1051,7 +1051,7 @@ sequences will be buffered internally and returned one byte at a time.
         the character that was received (can be multi-byte), or a complete ANSI sequence</li>
         <li>
            <span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
-        the type of input: <code>&quot;char&quot;</code> for a single key, <code>&quot;ansi&quot;</code> for an ANSI sequence</li>
+        the type of input: <code>&quot;ctrl&quot;</code> for 0-31 and 127 bytes, <code>&quot;char&quot;</code> for other UTF-8 characters, <code>&quot;ansi&quot;</code> for an ANSI sequence</li>
     </ol>
      <h3>Or</h3>
     <ol>
@@ -1070,6 +1070,15 @@ sequences will be buffered internally and returned one byte at a time.
 
 
 
+    <h3>Usage:</h3>
+    <ul>
+        <pre class="example"><span class="keyword">local</span> key, keytype = system.<span class="function-name">readansi</span>(<span class="number">5</span>)
+<span class="keyword">if</span> keytype == <span class="string">"char"</span> <span class="keyword">then</span> ... <span class="keyword">end</span> <span class="comment">-- printable character
+</span><span class="keyword">if</span> keytype ~= <span class="string">"char"</span> <span class="keyword">then</span> ... <span class="keyword">end</span> <span class="comment">-- non-printable character or sequence
+</span><span class="keyword">if</span> keytype == <span class="string">"ansi"</span> <span class="keyword">then</span> ... <span class="keyword">end</span> <span class="comment">-- a multi-byte sequence, but not a UTF8 character
+</span><span class="keyword">if</span> keytype ~= <span class="string">"ansi"</span> <span class="keyword">then</span> ... <span class="keyword">end</span> <span class="comment">-- a valid UTF8 character (which includes control characters)
+</span><span class="keyword">if</span> keytype == <span class="string">"ctrl"</span> <span class="keyword">then</span> ... <span class="keyword">end</span> <span class="comment">-- a single-byte ctrl character (0-31, 127)</span></pre>
+    </ul>
 
 </dd>
     <dt>
@@ -1079,7 +1088,7 @@ sequences will be buffered internally and returned one byte at a time.
     <dd>
     Reads a single byte from the console, with a timeout.
  This function uses <code>fsleep</code> to wait until either a byte is available or the timeout is reached.
- The sleep period is exponentially backing off, starting at 0.0125 seconds, with a maximum of 0.2 seconds.
+ The sleep period is exponentially backing off, starting at 0.0125 seconds, with a maximum of 0.1 seconds.
  It returns immediately if a byte is available or if <code>timeout</code> is less than or equal to <code>0</code>.</p>
 
 <p> Using <a href="../modules/system.html#readansi">system.readansi</a> is preferred over this function. Since this function can leave stray/invalid
@@ -1509,7 +1518,7 @@ This function will sleep, without doing a busy-loop and wasting CPU cycles.
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/topics/01-introduction.md.html b/docs/topics/01-introduction.md.html
index 5667e71..264aa71 100644
--- a/docs/topics/01-introduction.md.html
+++ b/docs/topics/01-introduction.md.html
@@ -84,7 +84,7 @@ independence.</p>
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/topics/02-development.md.html b/docs/topics/02-development.md.html
index 2432c98..15efe55 100644
--- a/docs/topics/02-development.md.html
+++ b/docs/topics/02-development.md.html
@@ -84,7 +84,7 @@ pass locally, and do not rely on CI only.</p>
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/topics/03-terminal.md.html b/docs/topics/03-terminal.md.html
index a7b600a..27772ac 100644
--- a/docs/topics/03-terminal.md.html
+++ b/docs/topics/03-terminal.md.html
@@ -220,7 +220,7 @@ For an example see <a href="../examples/password_input.lua.html"><code>examples/
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/topics/CHANGELOG.md.html b/docs/topics/CHANGELOG.md.html
index 8cd2966..9603abd 100644
--- a/docs/topics/CHANGELOG.md.html
+++ b/docs/topics/CHANGELOG.md.html
@@ -106,6 +106,19 @@
 <p><a name="Version_history"></a></p>
 <h2>Version history</h2>
 
+<h3>version 0.6.3, released 11-Jul-2025</h3>
+
+<ul>
+    <li>Fix: maximum key-delay, reduced from 0.2 to 0.1 seconds to reduce slugginess feel on some key presses.
+    See <a href="https://github.com/lunarmodules/luasystem/pull/69">#69</a>.</li>
+    <li>Fix: <code>readansi</code> now only reports printable chars as characters
+    See <a href="https://github.com/lunarmodules/luasystem/pull/70">#70</a>.</li>
+    <li>Fix: readkey now ignores Windows scancodes if received.
+    See <a href="https://github.com/lunarmodules/luasystem/pull/74">#74</a>.</li>
+    <li>Fix: readkey now passes errors on.
+    See <a href="https://github.com/lunarmodules/luasystem/pull/74">#74</a>.</li>
+</ul>
+
 <h3>version 0.6.2, released 15-Apr-2025</h3>
 
 <ul>
@@ -221,7 +234,7 @@
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/docs/topics/LICENSE.md.html b/docs/topics/LICENSE.md.html
index 90bdaa3..c0b9b93 100644
--- a/docs/topics/LICENSE.md.html
+++ b/docs/topics/LICENSE.md.html
@@ -94,7 +94,7 @@ SOFTWARE.</p>
 </div> <!-- id="main" -->
 <div id="about">
 <i>generated by <a href="http://github.com/lunarmodules/LDoc">LDoc 1.5.0</a></i>
-<i style="float:right;">Last updated 2025-04-17 09:50:39 </i>
+<i style="float:right;">Last updated 2025-07-11 22:55:05 </i>
 </div> <!-- id="about" -->
 </div> <!-- id="container" -->
 </body>
diff --git a/rockspecs/luasystem-0.6.3-1.rockspec b/rockspecs/luasystem-0.6.3-1.rockspec
new file mode 100644
index 0000000..e70373f
--- /dev/null
+++ b/rockspecs/luasystem-0.6.3-1.rockspec
@@ -0,0 +1,85 @@
+local package_name = "luasystem"
+local package_version = "0.6.3"
+local rockspec_revision = "1"
+local github_account_name = "lunarmodules"
+local github_repo_name = "luasystem"
+
+
+package = package_name
+version = package_version.."-"..rockspec_revision
+
+source = {
+  url = "git+https://github.com/"..github_account_name.."/"..github_repo_name..".git",
+  branch = (package_version == "scm") and "master" or nil,
+  tag = (package_version ~= "scm") and "v"..package_version or nil,
+}
+
+description = {
+  summary = 'Platform independent system calls for Lua.',
+  detailed = [[
+    Adds a Lua API for making platform independent system calls.
+  ]],
+  license = 'MIT <http://opensource.org/licenses/MIT>',
+  homepage = "https://github.com/"..github_account_name.."/"..github_repo_name,
+}
+
+dependencies = {
+  'lua >= 5.1',
+}
+
+local function make_platform(plat)
+  local defines = {
+    linux = { },
+    unix = { },
+    macosx = { },
+    win32 = { "WINVER=0x0600", "_WIN32_WINNT=0x0600" },
+    mingw32 = { "WINVER=0x0600", "_WIN32_WINNT=0x0600" },
+  }
+  local libraries = {
+    linux = { "rt" },
+    unix = { },
+    macosx = { },
+    win32 = { "advapi32", "winmm", "bcrypt" },
+    mingw32 = { },
+  }
+  local libdirs = {
+    linux = nil,
+    unix = nil,
+    macosx = nil,
+    win32 = nil,
+    mingw32 = { },
+  }
+  return {
+    modules = {
+      ['system.core'] = {
+        sources = {
+          'src/core.c',
+          'src/compat.c',
+          'src/time.c',
+          'src/environment.c',
+          'src/random.c',
+          'src/term.c',
+          'src/bitflags.c',
+          'src/wcwidth.c',
+        },
+        defines = defines[plat],
+        libraries = libraries[plat],
+        libdirs = libdirs[plat],
+      },
+    },
+  }
+end
+
+build = {
+  type = 'builtin',
+  platforms = {
+    linux = make_platform('linux'),
+    unix = make_platform('unix'),
+    macosx = make_platform('macosx'),
+    win32 = make_platform('win32'),
+    mingw32 = make_platform('mingw32'),
+  },
+  modules = {
+    ['system.init'] = 'system/init.lua',
+  },
+}
diff --git a/spec/04-term_spec.lua b/spec/04-term_spec.lua
index 0ce0033..5dea046 100644
--- a/spec/04-term_spec.lua
+++ b/spec/04-term_spec.lua
@@ -902,6 +902,14 @@ describe("Terminal:", function()
       end)
 
 
+      it("reads a control byte for single-byte control characters", function()
+        setbuffer("\000\031\127")
+        assert.are.same({"\000", "ctrl"}, {system.readansi(0)})
+        assert.are.same({"\031", "ctrl"}, {system.readansi(0)})
+        assert.are.same({"\127", "ctrl"}, {system.readansi(0)})
+      end)
+
+
       it("reads a multi-byte characters one at a time", function()
         setbuffer(string.char(226, 130, 172) ..        -- "€"   single
                   string.char(240, 159, 154, 128))     -- "🚀"  double
@@ -952,7 +960,7 @@ describe("Terminal:", function()
 
       it("returns a single <esc> character if no sequence is found", function()
         setbuffer("\27")
-        assert.are.same({"\27", "char"}, {system.readansi(0)})
+        assert.are.same({"\27", "ctrl"}, {system.readansi(0)})
       end)
 
 
diff --git a/src/core.c b/src/core.c
index 7776de4..34e19d8 100644
--- a/src/core.c
+++ b/src/core.c
@@ -4,7 +4,7 @@
 #include <lua.h>
 #include <lauxlib.h>
 
-#define LUASYSTEM_VERSION   "LuaSystem 0.6.2"
+#define LUASYSTEM_VERSION   "LuaSystem 0.6.3"
 
 #ifdef _WIN32
 #define LUAEXPORT __declspec(dllexport)
diff --git a/src/term.c b/src/term.c
index 6927bd9..0325208 100644
--- a/src/term.c
+++ b/src/term.c
@@ -908,7 +908,18 @@ static int lst_readkey(lua_State *L) {
     }
 
     wchar_t wc = _getwch();
-    // printf("----\nread wchar_t: %x\n", wc);
+    // printf("----\nread wchar_t: %x\n", (unsigned int)wc);
+
+    if (wc == 0x00 || wc == 0xE0) {
+        // printf("Ignoring scan code: %x\n", (unsigned int)wc);
+        // On Windows, especially with key-repeat, we can get native scancodes even if we've set the console
+        // to ANSI mode. Something, something, terminal not keeping up... These are not valid wide characters,
+        // so we ignore them. Scan codes start with either 0x00 or 0xE0, and have a follow up byte, which we all ignore.
+        // These codes are unique, so we do not risk dropping valid data.
+        _getwch(); // Discard 2nd half of the scan code
+        return 0;
+    }
+
     if (wc == WEOF) {
         lua_pushnil(L);
         lua_pushliteral(L, "read error");
@@ -929,7 +940,7 @@ static int lst_readkey(lua_State *L) {
             }
 
             wchar_t wc2 = _getwch();
-            // printf("read wchar_t 2: %x\n", wc2);
+            // printf("read wchar_t 2: %x\n", (unsigned int)wc2);
             if (wc2 == WEOF) {
                 lua_pushnil(L);
                 lua_pushliteral(L, "read error");
diff --git a/system/init.lua b/system/init.lua
index 9c86c4a..9b71d4d 100644
--- a/system/init.lua
+++ b/system/init.lua
@@ -239,7 +239,7 @@ end
 do
   --- Reads a single byte from the console, with a timeout.
   -- This function uses `fsleep` to wait until either a byte is available or the timeout is reached.
-  -- The sleep period is exponentially backing off, starting at 0.0125 seconds, with a maximum of 0.2 seconds.
+  -- The sleep period is exponentially backing off, starting at 0.0125 seconds, with a maximum of 0.1 seconds.
   -- It returns immediately if a byte is available or if `timeout` is less than or equal to `0`.
   --
   -- Using `system.readansi` is preferred over this function. Since this function can leave stray/invalid
@@ -256,19 +256,23 @@ do
     end
 
     local interval = 0.0125
-    local key = system._readkey()
+    local ok
+    local key, err = system._readkey()
     while key == nil and timeout > 0 do
-      local ok, err = (fsleep or system.sleep)(math.min(interval, timeout))
+      if err then
+        return nil, err
+      end
+      ok, err = (fsleep or system.sleep)(math.min(interval, timeout))
       if not ok then
         return nil, err
       end
       timeout = timeout - interval
-      interval = math.min(0.2, interval * 2)
-      key = system._readkey()
+      interval = math.min(0.1, interval * 2)
+      key, err = system._readkey()
     end
 
-    if key then
-      return key
+    if key or err then
+      return key, err
     end
     return nil, "timeout"
   end
@@ -290,13 +294,20 @@ do
   -- @tparam number timeout the timeout in seconds.
   -- @tparam[opt=system.sleep] function fsleep the function to call for sleeping.
   -- @treturn[1] string the character that was received (can be multi-byte), or a complete ANSI sequence
-  -- @treturn[1] string the type of input: `"char"` for a single key, `"ansi"` for an ANSI sequence
+  -- @treturn[1] string the type of input: `"ctrl"` for 0-31 and 127 bytes, `"char"` for other UTF-8 characters, `"ansi"` for an ANSI sequence
   -- @treturn[2] nil in case of an error
   -- @treturn[2] string error message; `"timeout"` if the timeout was reached.
   -- @treturn[2] string partial result in case of an error while reading a sequence, the sequence so far.
   -- The function retains its own internal buffer, so on the next call the incomplete buffer is used to
   -- complete the sequence.
   -- @within Terminal_Input
+  -- @usage
+  -- local key, keytype = system.readansi(5)
+  -- if keytype == "char" then ... end -- printable character
+  -- if keytype ~= "char" then ... end -- non-printable character or sequence
+  -- if keytype == "ansi" then ... end -- a multi-byte sequence, but not a UTF8 character
+  -- if keytype ~= "ansi" then ... end -- a valid UTF8 character (which includes control characters)
+  -- if keytype == "ctrl" then ... end -- a single-byte ctrl character (0-31, 127)
   function system.readansi(timeout, fsleep)
     if type(timeout) ~= "number" then
       error("arg #1 to readansi, expected timeout in seconds, got " .. type(timeout), 2)
@@ -320,7 +331,7 @@ do
         if key2 == nil then
           -- no key available, return the escape key, on its own
           sequence = nil
-          return string.char(key), "char"
+          return string.char(key), "ctrl"
 
         elseif key2 == 91 then
           -- "[" means it is for sure an ANSI sequence
@@ -351,10 +362,10 @@ do
       else
         -- check UTF8 length
         utf8_length = key < 128 and 1 or key < 224 and 2 or key < 240 and 3 or key < 248 and 4
-        if utf8_length  == 1 then
+        if utf8_length == 1 then
           -- single byte character
           utf8_length = nil
-          return string.char(key), "char"
+          return string.char(key), ((key <= 31 or key == 127) and "ctrl" or "char")
         else
           -- UTF8 sequence detected
           sequence = { key }