diff --git a/data/computercraft/lua/bios.lua b/data/computercraft/lua/bios.lua
index 0ed2c2b..2ac8510 100644
--- a/data/computercraft/lua/bios.lua
+++ b/data/computercraft/lua/bios.lua
@@ -1,4 +1,4 @@
-_G._HOST = _G._HOST .. " (LeonOS 0.2.6)"
+_G._HOST = _G._HOST .. " (LeonOS 0.2.7)"
 local fs = rawget(_G, "fs")
 
 _G._RC_ROM_DIR = _RC_ROM_DIR or (...) and fs.exists("/leonos") and "/leonos" or "/rom"
@@ -32,7 +32,7 @@ local rc = {
   _VERSION = {
     major = 0,
     minor = 2,
-    patch = 6
+    patch = 7
   },
   queueEvent  = pull(os, "queueEvent"),
   startTimer  = pull(os, "startTimer"),
diff --git a/data/computercraft/lua/rom/completions/calc.lua b/data/computercraft/lua/rom/completions/calc.lua
new file mode 100644
index 0000000..2f44d52
--- /dev/null
+++ b/data/computercraft/lua/rom/completions/calc.lua
@@ -0,0 +1,8 @@
+-- calc command completion
+local shell = require("shell")
+local completion = require("cc.shell.completion")
+
+shell.setCompletionFunction("calc", function(shell, args)
+  -- Calculator doesn't need parameters, return empty list
+  return {}
+end)
\ No newline at end of file
diff --git a/data/computercraft/lua/rom/programs/calc.lua b/data/computercraft/lua/rom/programs/calc.lua
new file mode 100644
index 0000000..a6d400b
--- /dev/null
+++ b/data/computercraft/lua/rom/programs/calc.lua
@@ -0,0 +1,89 @@
+-- Calculator program calc.lua
+local term = require("term")
+local keys = require("keys")
+local colors = require("colors")
+
+-- Function to draw top bar
+local function drawTopBar()
+    -- Get terminal size
+    local w, h = term.getSize()
+    
+    -- Save cursor position
+    local cx, cy = term.getCursorPos()
+    
+    -- Set top bar color
+    term.setTextColor(colors.yellow)
+    term.setBackgroundColor(colors.blue)
+    
+    -- Move to top-left corner
+    term.setCursorPos(1, 1)
+    
+    -- Draw top bar with centered title
+    local title = " LeonOS Calculator "
+    local padding = math.floor((w - #title) / 2)
+    term.write(string.rep(" ", padding) .. title .. string.rep(" ", padding))
+    
+    -- Reset colors
+    term.setTextColor(colors.white)
+    term.setBackgroundColor(colors.black)
+    
+    -- Restore cursor position
+    term.setCursorPos(cx, cy)
+end
+
+-- Clear screen and show UI
+term.clear()
+drawTopBar()
+
+-- Move cursor to below top bar and show instructions
+term.setCursorPos(1, 3)
+print("Enter an expression, press Enter to calculate (type 'q' to quit)")
+print("Supports +, -, *, /, ^(exponent), %(modulus), and parentheses")
+print("---------------------------")
+
+while true do
+    -- Show prompt
+    io.write("> ")
+    local input = io.read()
+    
+    -- Check for exit
+    if input == "q" or input == "quit" then
+        break
+    end
+    
+    -- Check for clear screen
+    if input == "clear" then
+        term.clear()
+drawTopBar()
+        -- Move cursor to below top bar and show instructions
+        term.setCursorPos(1, 3)
+        print("Enter an expression, press Enter to calculate (type 'q' to quit)")
+        print("Supports +, -, *, /, ^(exponent), %(modulus), and parentheses")
+        print("---------------------------")
+        goto continue
+    end
+    
+    -- Calculate expression
+    local success, result = pcall(function()
+        -- Replace Chinese parentheses with English ones
+        input = input:gsub("（", "("):gsub("）", ")")
+        -- Safely execute expression
+        local func = load("return " .. input)
+        if func then
+            return func()
+        else
+            error("Invalid expression")
+        end
+    end)
+    
+    -- Show result
+    if success then
+        print("Result: " .. result)
+    else
+        print("Error: " .. tostring(result))
+    end
+    
+    ::continue::
+end
+
+print("Calculator has exited")
\ No newline at end of file
diff --git a/data/computercraft/lua/rom/programs/shell.lua b/data/computercraft/lua/rom/programs/shell.lua
index 1cd5967..9f2cfd6 100644
--- a/data/computercraft/lua/rom/programs/shell.lua
+++ b/data/computercraft/lua/rom/programs/shell.lua
@@ -3,14 +3,12 @@
 -- 程序顶部名称栏
 local term = require("term")
 local colors = require("colors")
-local window = require("window")
 
 -- 保存当前颜色设置
 local old_fg = term.getTextColor()
 local old_bg = term.getBackgroundColor()
 
 -- 设置名称栏颜色并显示
-  term.setCursorPos(1, 1)
 term.setTextColor(colors.white)
 term.setBackgroundColor(colors.cyan)
 term.at(1, 1).clearLine()
@@ -102,99 +100,9 @@ while true do
     end
     term.at(1, 2)
     
-    -- 定义错误处理函数
-    local function showErrorWindow(errorMessage, command)
-      local w, h = term.getSize()
-      local winWidth, winHeight = 50, 12
-      local x = math.floor((w - winWidth) / 2)
-      local y = math.floor((h - winHeight) / 2)
-
-      -- 创建错误窗口
-      local errWindow = window.create(term.native(), x, y, winWidth, winHeight)
-      errWindow.setVisible(true)
-
-      -- 绘制窗口边框和标题
-      errWindow.setBackgroundColor(colors.red)
-      errWindow.setTextColor(colors.white)
-      errWindow.at(1, 1).clearLine()
-      errWindow.at(1, 1).write("=== 程序错误 ===")
-
-      -- 绘制窗口内容背景
-      errWindow.setBackgroundColor(colors.black)
-      for line=2, winHeight-1 do
-        errWindow.at(1, line).clearLine()
-      end
-
-      -- 显示错误信息（自动换行）
-      errWindow.setTextColor(colors.red)
-      errWindow.at(2, 2).write("错误信息:")
-      errWindow.setTextColor(colors.white)
-
-      local lineNum = 3
-      local maxLineLength = winWidth - 4
-      local messageLines = {}
-      local currentLine = ""
-
-      for word in errorMessage:gmatch("[^\s]+") do
-        if #currentLine + #word + 1 > maxLineLength then
-          table.insert(messageLines, currentLine)
-          currentLine = word
-        else
-          if currentLine == "" then
-            currentLine = word
-          else
-            currentLine = currentLine .. " " .. word
-          end
-        end
-      end
-      if currentLine ~= "" then
-        table.insert(messageLines, currentLine)
-      end
-
-      for _, line in ipairs(messageLines) do
-        if lineNum < winHeight - 2 then
-          errWindow.at(2, lineNum).write(line)
-          lineNum = lineNum + 1
-        else
-          errWindow.at(2, lineNum).write("...")
-          break
-        end
-      end
-
-      -- 绘制按钮
-      errWindow.setBackgroundColor(colors.gray)
-      errWindow.setTextColor(colors.white)
-      errWindow.at(5, winHeight-1).write("  确认  ")
-      errWindow.at(30, winHeight-1).write("  重新运行  ")
-
-      -- 处理用户输入
-      while true do
-        local event, button, xPos, yPos = os.pullEvent("mouse_click")
-        if yPos == winHeight-1 + y - 1 then
-          -- 点击确认按钮
-          if xPos >= x + 5 and xPos <= x + 12 then
-            errWindow.setVisible(false)
-            break
-          end
-          -- 点击重新运行按钮
-          if xPos >= x + 30 and xPos <= x + 42 then
-            errWindow.setVisible(false)
-            return true
-          end
-        end
-      end
-      return false
-    end
-
     local ok, err = shell.run(text)
     if not ok and err then
-      local shouldRetry = showErrorWindow(err, text)
-      if shouldRetry then
-        history[#history] = nil -- 移除当前命令，避免历史记录重复
-        term.at(1, 2).clearLine()
-        goto continue -- 重新运行命令
-      end
+      io.stderr:write("Application has a error when running and system has stop it. Error:\n", err, "\n")
     end
-    ::continue::
   end
 end
\ No newline at end of file
diff --git a/installer.lua b/installer.lua
index b366c7a..10ce940 100644
--- a/installer.lua
+++ b/installer.lua
@@ -1,5 +1,5 @@
 -- LeonOS installer
-local INSTALLER_VERSION = "0.2.6"
+local INSTALLER_VERSION = "0.2.7"
 local DEFAULT_ROM_DIR = "/leonos"
 
 print("Start loading LeonOS installer ("..INSTALLER_VERSION..")...")