diff --git a/pipelined-cpu/srcs/board/cpu21_saolei_rom.vh b/pipelined-cpu/srcs/board/cpu21_saolei_rom.vh
index edc6684..a802a7e 100644
--- a/pipelined-cpu/srcs/board/cpu21_saolei_rom.vh
+++ b/pipelined-cpu/srcs/board/cpu21_saolei_rom.vh
@@ -310,7 +310,7 @@
     rom[307] = 32'h79402703;
     rom[308] = 32'h01F7F793;
     rom[309] = 32'h00879793;
-    rom[310] = 32'h01F77713;
+    rom[310] = 32'h03F77713;
     rom[311] = 32'h00E7E7B3;
     rom[312] = 32'h00001737;
     rom[313] = 32'h14F72223;
diff --git a/pipelined-cpu/srcs/rtl/cpu21_vga.v b/pipelined-cpu/srcs/rtl/cpu21_vga.v
index 7bb4a38..5a86bd7 100644
--- a/pipelined-cpu/srcs/rtl/cpu21_vga.v
+++ b/pipelined-cpu/srcs/rtl/cpu21_vga.v
@@ -280,7 +280,9 @@ module cpu21_vga #(
   //   VGA 上和图里都能一眼看到指针。想改回闪动：把 blink_q 加回来，
   //   再在 cursor_box 里与上 blink 即可。
   // ---------------------------------------------------------------------------
-  wire cursor_here = (cursor_i[4:0] == ccol) && (cursor_i[12:8] == crow);
+  // 列必须比 6 位（0..39）：hard 难度的棋盘宽 30，光标能到列 35，
+  // 以前这里只取 [4:0]，35 被当成 3，光标会“跳回最左边”。
+  wire cursor_here = (cursor_i[5:0] == ccol) && (cursor_i[12:8] == crow);
   wire on_border = (hx[3:0] < 4'd2) || (hx[3:0] > 4'd13) || (vy[3:0] < 4'd2) || (vy[3:0] > 4'd13);
   wire cursor_box = cursor_here && ctrl_i[0] && on_border;
 
diff --git a/saolei/sw/saolei.c b/saolei/sw/saolei.c
index c9bd06e..a783705 100644
--- a/saolei/sw/saolei.c
+++ b/saolei/sw/saolei.c
@@ -199,7 +199,8 @@ static void draw_all_covered(void)
 
 static void update_cursor_reg(void)
 {
-    REG_W(REG_CURSOR) = (cur_c & 31u) | ((cur_r & 31u) << 8);
+    /* 列用 6 位（0..39）：hard 棋盘宽 30，光标列能到 35，掩 31 会把它变成 3 */
+    REG_W(REG_CURSOR) = (cur_c & 63u) | ((cur_r & 31u) << 8);
 }
 
 static void set_bg(unsigned color)