diff --git a/assets/tvdos/bin/hexdump.js b/assets/tvdos/bin/hexdump.js
new file mode 100644
index 0000000..e55d594
--- /dev/null
+++ b/assets/tvdos/bin/hexdump.js
@@ -0,0 +1,20 @@
+if (exec_args[1] === undefined) {
+    printerrln("Usage: hexdump <file>")
+    return 1;
+}
+
+let fileOpened = filesystem.open(_G.shell.getCurrentDrive(), _G.shell.resolvePathInput(exec_args[1]).string, "R");
+if (!fileOpened) {
+    printerrln(_G.shell.resolvePathInput(exec_args[1]).string+": cannot open");
+    return 1;
+}
+let fileContent = filesystem.readAll(_G.shell.getCurrentDrive());
+let visible = "";
+
+for (let k = 0; k < fileContent.length; k++) {
+    if (k > 0 && k % 16 == 0) visible += "\n";
+    visible += `${fileContent.charCodeAt(k).toString(16).toUpperCase().padStart(2, '0')} `;
+}
+
+println(visible);
+return 0;
\ No newline at end of file
diff --git a/assets/tvdos/bin/less.js b/assets/tvdos/bin/less.js
index 25b1b6d..b2cf70d 100644
--- a/assets/tvdos/bin/less.js
+++ b/assets/tvdos/bin/less.js
@@ -29,6 +29,7 @@ let buf = "";
 let fileContent = filesystem.readAll(_G.shell.getCurrentDrive());
 let key = -1;
 let panSize = termW >> 1;
+let scrollSize = termH >> 3;
 
 // initialise some helper variables
 let lineToBytes = [0];
@@ -50,6 +51,12 @@ let cy = 1;
 let cx = 1;
 let char = -1;
 
+let numbuf = 0;
+
+let resetKeyReadStatus = function() {
+    numbuf = 0;
+}
+
 let repaint = function() {
     con.move(1,1); con.clear();
 
@@ -75,20 +82,23 @@ let repaint = function() {
 }
 
 repaint();
+con.move(termH + 1, 1);
+print(":"+" ".repeat(termW - 2));
+con.move(termH + 1, 2);
 while (true) {
     // read a key
-    con.mvaddch(termH + 1,1,58);
-    con.move(termH + 1, 2);
     key = con.getch();
     // do something with key read
     /*Q*/if (key == 113 || key == 81) break;
     /*R*/else if (key == 114 || key == 82) repaint();
-    /*up*/else if (key == 19 && scroll > 0) {
-        scroll -= 1;
+    /*up*/else if (key == 19) {
+        scroll -= scrollSize;
+        if (scroll < 0) scroll = 0;
         repaint();
     }
-    /*down*/else if (key == 20 && scroll < lineToBytes.length - termH) {
-        scroll += 1;
+    /*down*/else if (key == 20) {
+        scroll += scrollSize;
+        if (scroll > lineToBytes.length - termH) scroll = lineToBytes.length - termH;
         repaint();
     }
     /*left*/else if (key == 21 && pan > 0) {
@@ -99,6 +109,34 @@ while (true) {
         pan += panSize;
         repaint();
     }
+    /*0-9*/else if (key >= 48 && key <= 57) {
+        print(String.fromCharCode(key));
+        numbuf = (numbuf * 10) + (key - 48);
+    }
+    /*bksp*/else if (key == 8) {
+        if (numbuf > 0) print(String.fromCharCode(key));
+        numbuf = (numbuf / 10)|0;
+    }
+    /*u*/else if (key == 117) {
+        scroll -= numbuf;
+        if (scroll < 0) scroll = 0;
+        repaint();
+    }
+    /*d*/else if (key == 100) {
+        scroll += numbuf;
+        if (scroll > lineToBytes.length - termH) scroll = lineToBytes.length - termH;
+        repaint();
+    }
+
+
+    if (!(key >= 48 && key <= 57 || key == 8)) {
+        resetKeyReadStatus();
+        con.move(termH + 1, 1);
+        print(":"+" ".repeat(termW - 2));
+        con.move(termH + 1, 2);
+    }
+
+    serial.println("numbuf = "+numbuf);
 }
 
 con.move(termH + 1, 1);