diff --git a/maple/maple_bus_ft6_key_scan_codes.hpp b/maple/maple_bus_ft6_key_scan_codes.hpp
index 70df769..9a8f919 100644
--- a/maple/maple_bus_ft6_key_scan_codes.hpp
+++ b/maple/maple_bus_ft6_key_scan_codes.hpp
@@ -91,6 +91,7 @@ namespace ft6 {
 }
 namespace ft6 {
   namespace scan_code {
+    constexpr uint32_t first_printable = 0x4;
     constexpr uint32_t last_printable = 0x38;
 
     const uint8_t code_point[last_printable + 1][2] = {
@@ -154,4 +155,3 @@ namespace ft6 {
     };
   }
 }
-
diff --git a/text_editor/gap_buffer.cpp b/text_editor/gap_buffer.cpp
index 3edcf2a..8151289 100644
--- a/text_editor/gap_buffer.cpp
+++ b/text_editor/gap_buffer.cpp
@@ -127,7 +127,7 @@ void gap_cursor_pos_abs(struct gap_buffer& gb, int32_t pos)
   gap_cursor_pos(gb, pos - gb.gap_start);
 }
 
-int32_t gap_column_number(struct gap_buffer& gb)
+int32_t gap_column_number(const struct gap_buffer& gb)
 {
   int32_t line_start = 0;
   if (gb.line.gap > 0)
diff --git a/text_editor/gap_buffer.hpp b/text_editor/gap_buffer.hpp
index 17e12d9..8fa2ab7 100644
--- a/text_editor/gap_buffer.hpp
+++ b/text_editor/gap_buffer.hpp
@@ -32,5 +32,5 @@ void gap_resize(struct gap_buffer& gb);
 void gap_append(struct gap_buffer& gb, char_type c);
 void gap_pop(struct gap_buffer& gb);
 void gap_cursor_pos(struct gap_buffer& gb, int32_t delta);
-int32_t gap_column_number(struct gap_buffer& gb);
+int32_t gap_column_number(const struct gap_buffer& gb);
 void gap_cursor_pos_line(struct gap_buffer& gb, int32_t delta);
diff --git a/text_editor/keyboard.cpp b/text_editor/keyboard.cpp
index 95a0297..ac953f4 100644
--- a/text_editor/keyboard.cpp
+++ b/text_editor/keyboard.cpp
@@ -119,14 +119,36 @@ void keyboard_debug(ft6::data_transfer::data_format * keyboards, uint32_t frame_
   }
 }
 
-static inline bool is_shifted(const uint8_t modifier_key)
+constexpr inline bool is_modified(uint32_t modifier, uint32_t bit)
 {
-  return
-    (ft6::data_transfer::modifier_key::right_shift() & modifier_key) ||
-    (ft6::data_transfer::modifier_key::left_shift() & modifier_key);
+  uint32_t mask = ~(bit);
+  return ((modifier & bit) != 0) && ((modifier & mask) == 0);
 }
 
-void keyboard_update(ft6::data_transfer::data_format * keyboards, uint32_t frame_ix, gap_buffer& gb)
+constexpr inline bool is_unmodified(uint32_t modifier)
+{
+  return modifier == 0;
+}
+
+constexpr inline bool is_shifted(uint32_t modifier)
+{
+  uint32_t bit = ft6::data_transfer::modifier_key::right_shift() | ft6::data_transfer::modifier_key::left_shift();
+  return is_modified(modifier, bit);
+}
+
+constexpr inline bool is_left_alted(uint32_t modifier)
+{
+  uint32_t bit = (ft6::data_transfer::modifier_key::left_alt());
+  return is_modified(modifier, bit);
+}
+
+constexpr inline bool is_ctrled(uint32_t modifier)
+{
+  uint32_t bit = (ft6::data_transfer::modifier_key::left_control() | ft6::data_transfer::modifier_key::right_control());
+  return is_modified(modifier, bit);
+}
+
+void keyboard_update(ft6::data_transfer::data_format * keyboards, uint32_t frame_ix, gap_buffer& gb, viewport_window& vw)
 {
   uint32_t this_frame = (frame_ix + 0) & 1;
   uint32_t next_frame = (frame_ix + 1) & 1;
@@ -144,26 +166,56 @@ void keyboard_update(ft6::data_transfer::data_format * keyboards, uint32_t frame
     }
     if (make) {
       // make
+      int modifier_key = keyboards[this_frame].modifier_key;
       uint8_t scan_code = keyboards[this_frame].scan_code_array[i];
-      if (scan_code <= ft6::scan_code::last_printable) {
-	bool shifted = is_shifted(keyboards[this_frame].modifier_key);
-	char_type code_point = ft6::scan_code::code_point[scan_code][shifted];
-	if (code_point != 0) {
-	  gap_append(gb, code_point);
-	  continue;
-	}
-      }
-      switch (scan_code) {
-	case ft6::scan_code::_return:   gap_append(gb, '\n'); break;
-	case ft6::scan_code::backspace: gap_pop(gb);          break;
-	case ft6::scan_code::spacebar:  gap_append(gb, ' ');  break;
 
-	case ft6::scan_code::left_arrow:  gap_cursor_pos(gb, -1);      break;
-	case ft6::scan_code::right_arrow: gap_cursor_pos(gb, 1);       break;
-	case ft6::scan_code::up_arrow:    gap_cursor_pos_line(gb, -1); break;
-	case ft6::scan_code::down_arrow:  gap_cursor_pos_line(gb, 1);  break;
-	default:
-	  break;
+      if (is_shifted(modifier_key) || is_unmodified(modifier_key)) {
+        if (scan_code >= ft6::scan_code::first_printable && scan_code <= ft6::scan_code::last_printable) {
+          bool shifted = is_shifted(modifier_key);
+          char_type code_point = ft6::scan_code::code_point[scan_code][shifted];
+          if (code_point != 0) {
+            gap_append(gb, code_point);
+            continue;
+          }
+        }
+      }
+
+      if (is_unmodified(modifier_key)) {
+        switch (scan_code) {
+        case ft6::scan_code::_return:   gap_append(gb, '\n'); break;
+        case ft6::scan_code::backspace: gap_pop(gb);          break;
+        case ft6::scan_code::spacebar:  gap_append(gb, ' ');  break;
+
+        case ft6::scan_code::left_arrow:  gap_cursor_pos(gb, -1);      break;
+        case ft6::scan_code::right_arrow: gap_cursor_pos(gb, 1);       break;
+        case ft6::scan_code::up_arrow:    gap_cursor_pos_line(gb, -1); break;
+        case ft6::scan_code::down_arrow:  gap_cursor_pos_line(gb, 1);  break;
+
+        default: break;
+        }
+      }
+
+      if (is_left_alted(modifier_key)) {
+        switch (scan_code) {
+        case ft6::scan_code::v_V:
+          vw.first_line -= 1;
+          if (vw.first_line < 0)
+            vw.first_line = 0;
+          break;
+        default: break;
+        }
+      }
+
+      if (is_ctrled(modifier_key)) {
+        switch (scan_code) {
+        case ft6::scan_code::v_V:
+          vw.first_line += 1;
+          if ((vw.first_line - 1) >= gb.line.length) {
+            vw.first_line = gb.line.length;
+          }
+          break;
+        default: break;
+        }
       }
     }
   }
diff --git a/text_editor/keyboard.hpp b/text_editor/keyboard.hpp
index 3593c1b..de298c7 100644
--- a/text_editor/keyboard.hpp
+++ b/text_editor/keyboard.hpp
@@ -4,9 +4,10 @@
 
 #include "maple/maple_bus_ft6.hpp"
 #include "gap_buffer.hpp"
+#include "viewport_window.hpp"
 
 void keyboard_do_get_condition(ft6::data_transfer::data_format& data);
 
 void keyboard_debug(ft6::data_transfer::data_format * keyboards, uint32_t frame_ix);
 
-void keyboard_update(ft6::data_transfer::data_format * keyboards, uint32_t frame_ix, gap_buffer& gb);
+void keyboard_update(ft6::data_transfer::data_format * keyboards, uint32_t frame_ix, gap_buffer& gb, viewport_window& vw);
diff --git a/text_editor/parse.cpp b/text_editor/parse.cpp
new file mode 100644
index 0000000..b47d706
--- /dev/null
+++ b/text_editor/parse.cpp
@@ -0,0 +1,70 @@
+#include <stddef.h>
+
+#include "parse.hpp"
+
+int parse_base10_digit(char c)
+{
+  switch (c) {
+  case '0': return 0;
+  case '1': return 1;
+  case '2': return 2;
+  case '3': return 3;
+  case '4': return 4;
+  case '5': return 5;
+  case '6': return 6;
+  case '7': return 7;
+  case '8': return 8;
+  case '9': return 9;
+  default: return -1;
+  }
+}
+
+const char * parse_base10(const char * s, int * n)
+{
+  *n = 0;
+  int sign = 1;
+
+  if (*s == '-') {
+    sign = -1;
+    s++;
+  }
+
+  while (true) {
+    int digit = parse_base10_digit(*s);
+    if (digit == -1)
+      break;
+
+    *n *= 10;
+    *n += digit;
+    s++;
+  }
+
+  *n *= sign;
+
+  return s;
+}
+
+const char * parse_base10_64(const char * s, int64_t * n)
+{
+  *n = 0;
+  int sign = 1;
+
+  if (*s == '-') {
+    sign = -1;
+    s++;
+  }
+
+  while (true) {
+    int digit = parse_base10_digit(*s);
+    if (digit == -1)
+      break;
+
+    *n *= 10;
+    *n += digit;
+    s++;
+  }
+
+  *n *= sign;
+
+  return s;
+}
diff --git a/text_editor/parse.hpp b/text_editor/parse.hpp
new file mode 100644
index 0000000..88e1224
--- /dev/null
+++ b/text_editor/parse.hpp
@@ -0,0 +1,5 @@
+#include <stddef.h>
+
+int parse_base10_digit(char c);
+const char * parse_base10(const char * s, int * n);
+const char * parse_base10_64(const char * s, int64_t * n);
diff --git a/text_editor/printf.cpp b/text_editor/printf.cpp
new file mode 100644
index 0000000..9e15ca9
--- /dev/null
+++ b/text_editor/printf.cpp
@@ -0,0 +1,173 @@
+#include <stdint.h>
+#include <stdarg.h>
+
+#include "parse.hpp"
+#include "unparse.hpp"
+#include "printf.hpp"
+
+enum format_type {
+  FORMAT_BASE10_UNSIGNED,
+  FORMAT_BASE10,
+  FORMAT_BASE10_64,
+  FORMAT_POINTER,
+  FORMAT_BASE16,
+  FORMAT_STRING,
+  FORMAT_CHAR,
+  FORMAT_PERCENT,
+};
+
+struct format {
+  enum format_type type;
+  int pad_length;
+  char fill_char;
+};
+
+static const char * parse_escape(const char * format, struct format * ft);
+
+static const char * parse_fill_pad(const char * format, struct format * ft)
+{
+  if (*format == 0)
+    return format;
+  if (*format >= '1' || *format <= '9')
+    ft->fill_char = ' ';
+  else
+    ft->fill_char = *format++;
+  format = parse_base10(format, &ft->pad_length);
+  return parse_escape(format, ft);
+}
+
+static const char * parse_escape(const char * format, struct format * ft)
+{
+  switch (*format) {
+  case 0:
+    return format;
+  case 'u':
+    ft->type = FORMAT_BASE10_UNSIGNED;
+    return format + 1;
+  case 'd':
+    ft->type = FORMAT_BASE10;
+    return format + 1;
+  case 'l':
+    ft->type = FORMAT_BASE10_64;
+    return format + 1;
+  case 'p':
+    ft->type = FORMAT_POINTER;
+    return format + 1;
+  case 'x':
+    ft->type = FORMAT_BASE16;
+    return format + 1;
+  case 's':
+    ft->type = FORMAT_STRING;
+    return format + 1;
+  case 'c':
+    ft->type = FORMAT_CHAR;
+    return format + 1;
+  case '%':
+    ft->type = FORMAT_PERCENT;
+    return format + 1;
+  default:
+    return parse_fill_pad(format, ft);
+  }
+}
+
+static inline int copy_string(const char * src, int src_len, char * dst, int dst_len, int dst_ix)
+{
+  int i;
+  for (i = 0; i < src_len; i++) {
+    if (dst_ix + i >= dst_len)
+      break;
+    dst[dst_ix + i] = src[i];
+  }
+  return i;
+}
+
+int snprintf(char * buf, int buf_len, const char * format, ...)
+{
+  va_list args;
+  va_start(args, format);
+
+  int buf_ix = 0;
+
+  while (buf_ix < buf_len) {
+    if (*format == 0)
+      break;
+
+    switch (*format) {
+    case '%':
+      {
+        struct format ft;
+        ft.pad_length = 0;
+        ft.fill_char = 0;
+        format = parse_escape(format + 1, &ft);
+        switch (ft.type) {
+        case FORMAT_BASE10_UNSIGNED:
+          {
+            uint32_t num = va_arg(args, uint32_t);
+            char s[10];
+            int offset = unparse_base10_unsigned(s, num, ft.pad_length, ft.fill_char);
+            buf_ix += copy_string(s, offset, buf, buf_len, buf_ix);
+          }
+          break;
+        case FORMAT_BASE10:
+          {
+            int32_t num = va_arg(args, int32_t);
+            char s[10];
+            int offset = unparse_base10(s, num, ft.pad_length, ft.fill_char);
+            buf_ix += copy_string(s, offset, buf, buf_len, buf_ix);
+          }
+          break;
+        case FORMAT_BASE10_64:
+          {
+            int64_t num = va_arg(args, int64_t);
+            char s[20];
+            int offset = unparse_base10_64(s, num, ft.pad_length, ft.fill_char);
+            buf_ix += copy_string(s, offset, buf, buf_len, buf_ix);
+          }
+          break;
+        case FORMAT_POINTER:
+          {
+            const char s[2] = {'0', 'x'};
+            buf_ix += copy_string(s, 2, buf, buf_len, buf_ix);
+          }
+          /* fall through */;
+        case FORMAT_BASE16:
+          {
+            uint32_t num = va_arg(args, uint32_t);
+            char s[8];
+            int offset = unparse_base16(s, num, ft.pad_length, ft.fill_char);
+            buf_ix += copy_string(s, offset, buf, buf_len, buf_ix);
+          }
+          break;
+        case FORMAT_STRING:
+          {
+            const char * s = va_arg(args, const char *);
+            while (*s != 0 && buf_ix < buf_len) {
+              buf[buf_ix++] = *s++;
+            }
+          }
+          break;
+        case FORMAT_CHAR:
+          {
+            const int c = va_arg(args, const int);
+            buf[buf_ix++] = c;
+          }
+          break;
+        case FORMAT_PERCENT:
+          buf[buf_ix++] = '%';
+          break;
+        }
+      }
+      break;
+    default:
+      {
+        char c = *format++;
+        buf[buf_ix++] = c;
+      }
+      break;
+    }
+  }
+
+  va_end(args);
+
+  return buf_ix;
+}
diff --git a/text_editor/printf.hpp b/text_editor/printf.hpp
new file mode 100644
index 0000000..090d264
--- /dev/null
+++ b/text_editor/printf.hpp
@@ -0,0 +1,3 @@
+#pragma once
+
+int snprintf(char * buf, int len, const char * format, ...);
diff --git a/text_editor/render.cpp b/text_editor/render.cpp
index 314f411..9e2e895 100644
--- a/text_editor/render.cpp
+++ b/text_editor/render.cpp
@@ -1,6 +1,7 @@
 #include "render.hpp"
 #include "minmax.hpp"
 #include "transform.hpp"
+#include "unparse.hpp"
 
 #include "holly/ta_global_parameter.hpp"
 #include "holly/ta_fifo_polygon_converter.hpp"
@@ -36,9 +37,11 @@ cursor_advance render_primary_buffer(ta_parameter_writer& writer,
                                      const gap_buffer& gb,
                                      const viewport_window& window)
 {
-  int32_t first_line = min(window.first_line, gb.line.length - 1);
+  int32_t first_line = window.first_line;
 
   cursor_advance cursor = { 0 };
+  cursor.x = -1;
+  cursor.y = -1;
   int32_t h_advance = 0;
   int32_t v_advance = 0;
 
@@ -47,7 +50,16 @@ cursor_advance render_primary_buffer(ta_parameter_writer& writer,
 
   int row = first_line;
 
-  int32_t init_i = first_line >= 0 ? gb.line.offsets[first_line] + 1 : 0;
+  // line 0 is prior to the beginning of gb.line.offsets
+  // gb.line.offsets is the index of the newline character
+  int32_t init_i;
+  if (first_line == 0) {
+    init_i = 0;
+  } else if ((first_line - 1) >= 0 && (first_line - 1) < gb.line.length) {
+    init_i = gb.line.offsets[first_line - 1] + 1;
+  } else {
+    init_i = gb.size;
+  }
   for (int32_t i = init_i; i <= gb.size; i++) {
     if (i == gb.gap_start) {
       uint32_t ix = get_font_ix(font, ' ');
@@ -97,7 +109,41 @@ cursor_advance render_primary_buffer(ta_parameter_writer& writer,
   return cursor;
 }
 
-void render_cursor(ta_parameter_writer& parameter,
+void render_text(ta_parameter_writer& writer,
+                 const font * font,
+                 const glyph * glyphs,
+                 const char * buf,
+                 int length,
+                 int32_t x0,
+                 int32_t y0)
+{
+  int32_t h_advance = 0;
+  int32_t v_advance = 0;
+
+  const float r_texture_width = 1.0f / font->texture_width;
+  const float r_texture_height = 1.0f / font->texture_height;
+
+  for (int i = 0; i < length; i++) {
+    int32_t x = x0 + int_26_6(h_advance);
+    int32_t y = y0 + int_26_6(v_advance);
+
+    char_type c = buf[i];
+    uint32_t ix = get_font_ix(font, c);
+    auto& glyph = glyphs[ix];
+
+    transform_glyph(writer,
+                    r_texture_width,
+                    r_texture_height,
+                    glyph,
+                    x,
+                    y
+                    );
+
+    h_advance += glyph.metrics.horiAdvance;
+  }
+}
+
+void render_cursor(ta_parameter_writer& writer,
 		   const cursor_advance& cursor,
 		   const viewport_window& window)
 {
@@ -106,7 +152,7 @@ void render_cursor(ta_parameter_writer& parameter,
   float width = int_26_6(cursor.width);
   float height = int_26_6(cursor.height);
 
-  transform_cursor(parameter,
+  transform_cursor(writer,
 		   x, // x
 		   y, // y
 		   width,
@@ -114,6 +160,39 @@ void render_cursor(ta_parameter_writer& parameter,
 		   );
 }
 
+static inline int copy_str(const char * s, char * d, int d_ix)
+{
+  while (*s != 0) {
+    d[d_ix++] = *s++;
+  }
+  return d_ix;
+}
+
+void render_status(ta_parameter_writer& writer,
+                   const font * font,
+                   const glyph * glyphs,
+                   const gap_buffer& gb,
+                   const viewport_window& window)
+{
+  char buf[256];
+  int ix = 0;
+
+  ix = copy_str("(", buf, ix);
+  ix += unparse_base10(&buf[ix], gb.line.gap, 0, 0);
+  ix = copy_str(",", buf, ix);
+  ix += unparse_base10(&buf[ix], gap_column_number(gb), 0, 0);
+  ix = copy_str(")  ", buf, ix);
+  ix += unparse_base10(&buf[ix], window.first_line, 0, 0);
+
+  render_text(writer,
+              font,
+              glyphs,
+              buf,
+              ix,
+              window.box.x0,
+              480 - int_26_6(font->face_metrics.height) * 2);
+}
+
 void render(ta_parameter_writer& writer,
             const font * font,
             const glyph * glyphs,
@@ -124,6 +203,8 @@ void render(ta_parameter_writer& writer,
               font->texture_width,
               font->texture_height);
 
+  render_status(writer, font, glyphs, gb, window);
+
   cursor_advance cursor = render_primary_buffer(writer, font, glyphs, gb, window);
 
   render_cursor(writer, cursor, window);
diff --git a/text_editor/text_editor.cpp b/text_editor/text_editor.cpp
index 095d955..8de97bf 100644
--- a/text_editor/text_editor.cpp
+++ b/text_editor/text_editor.cpp
@@ -256,7 +256,7 @@ void main()
   struct editor_state state = { 0 };
   gap_init_from_buf(state.gb, buf, buf_size, 0);
   line_init_from_buf(state.gb, offsets, offsets_size);
-  viewport_init_fullscreen(state.window);
+  viewport_init_fullscreen(state.window, font);
 
   ft6::data_transfer::data_format keyboards[2] = { 0 };
 
@@ -269,7 +269,7 @@ void main()
   while (true) {
     keyboard_do_get_condition(keyboards[frame_ix & 1]);
     keyboard_debug(keyboards, frame_ix);
-    keyboard_update(keyboards, frame_ix, state.gb);
+    keyboard_update(keyboards, frame_ix, state.gb, state.window);
 
     ta_polygon_converter_init2(texture_memory_alloc.isp_tsp_parameters[0].start,
 			       texture_memory_alloc.isp_tsp_parameters[0].end,
diff --git a/text_editor/text_editor.mk b/text_editor/text_editor.mk
index 8e7d879..70760e1 100644
--- a/text_editor/text_editor.mk
+++ b/text_editor/text_editor.mk
@@ -4,6 +4,7 @@ TEXT_EDITOR_OBJ = \
 	text_editor/render.o \
 	text_editor/keyboard.o \
 	text_editor/transform.o \
+	text_editor/unparse.o \
 	holly/video_output.o \
 	holly/core.o \
 	holly/region_array.o \
diff --git a/text_editor/transform.cpp b/text_editor/transform.cpp
index eb59572..cd337d9 100644
--- a/text_editor/transform.cpp
+++ b/text_editor/transform.cpp
@@ -204,6 +204,6 @@ void transform_glyph(ta_parameter_writer& writer,
   }
 
   const float z = 0.1f;
-  uint32_t base_color = 0xff0080ff;
+  uint32_t base_color = 0xffffff;
   transfer_quad_type_3(writer, out[0], out[1], out[2], out[3], z, base_color);
 }
diff --git a/text_editor/unparse.cpp b/text_editor/unparse.cpp
new file mode 100644
index 0000000..9157922
--- /dev/null
+++ b/text_editor/unparse.cpp
@@ -0,0 +1,165 @@
+#include "minmax.hpp"
+#include "unparse.hpp"
+
+int digits_base10(uint32_t n)
+{
+  if (n >= 1000000000ul) return 10;
+  if (n >= 100000000ul) return 9;
+  if (n >= 10000000ul) return 8;
+  if (n >= 1000000ul) return 7;
+  if (n >= 100000ul) return 6;
+  if (n >= 10000ul) return 5;
+  if (n >= 1000ul) return 4;
+  if (n >= 100ul) return 3;
+  if (n >= 10ul) return 2;
+  return 1;
+}
+
+int unparse_base10_unsigned(char * s, uint32_t n, int len, char fill)
+{
+  int digits = 0;
+  digits += digits_base10(n);
+  len = max(digits, len);
+  int ret = len;
+
+  while (len > digits) {
+    *s++ = fill;
+    --len;
+  }
+
+  while (len > 0) {
+    const uint32_t digit = n % 10;
+    n = n / 10;
+    s[--len] = digit + 48;
+  }
+
+  return ret;
+}
+
+int unparse_base10(char * s, int32_t n, int len, char fill)
+{
+  bool negative = false;
+  int digits = 0;
+  if (n < 0) {
+    digits += 1;
+    n = -n;
+    negative = true;
+  }
+
+  digits += digits_base10(n);
+  len = max(digits, len);
+  int ret = len;
+
+  while (len > digits) {
+    *s++ = fill;
+    --len;
+  }
+
+  if (negative) {
+    *s++ = '-';
+    len--;
+  }
+
+  while (len > 0) {
+    const uint32_t digit = n % 10;
+    n = n / 10;
+    s[--len] = digit + 48;
+  }
+
+  return ret;
+}
+
+int digits_base10_64(uint64_t n)
+{
+  if (n >= 10000000000000000000ull) return 20;
+  if (n >= 1000000000000000000ull) return 19;
+  if (n >= 100000000000000000ull) return 18;
+  if (n >= 10000000000000000ull) return 17;
+  if (n >= 1000000000000000ull) return 16;
+  if (n >= 100000000000000ull) return 15;
+  if (n >= 10000000000000ull) return 14;
+  if (n >= 1000000000000ull) return 13;
+  if (n >= 100000000000ull) return 12;
+  if (n >= 10000000000ull) return 11;
+  if (n >= 1000000000ull) return 10;
+  if (n >= 100000000ull) return 9;
+  if (n >= 10000000ull) return 8;
+  if (n >= 1000000ull) return 7;
+  if (n >= 100000ull) return 6;
+  if (n >= 10000ull) return 5;
+  if (n >= 1000ull) return 4;
+  if (n >= 100ull) return 3;
+  if (n >= 10ull) return 2;
+  return 1;
+}
+
+int unparse_base10_64(char * s, int64_t n, int len, char fill)
+{
+  bool negative = false;
+  int digits = 0;
+  if (n < 0) {
+    digits += 1;
+    n = -n;
+    negative = true;
+  }
+
+  digits += digits_base10_64(n);
+  len = max(digits, len);
+  int ret = len;
+
+  while (len > digits) {
+    *s++ = fill;
+    --len;
+  }
+
+  if (negative) {
+    *s++ = '-';
+    len--;
+  }
+
+  while (len > 0) {
+    const uint32_t digit = n % 10;
+    n = n / 10;
+    s[--len] = digit + 48;
+  }
+
+  return ret;
+}
+
+static int digits_base16(uint32_t n)
+{
+  if (n <= 0xf) return 1;
+  if (n <= 0xff) return 2;
+  if (n <= 0xfff) return 3;
+  if (n <= 0xffff) return 4;
+  if (n <= 0xfffff) return 5;
+  if (n <= 0xffffff) return 6;
+  if (n <= 0xfffffff) return 7;
+  return 8;
+}
+
+int unparse_base16(char * s, uint32_t n, int len, char fill)
+{
+  int digits = digits_base16(n);
+  len = max(digits, len);
+  int ret = len;
+
+  while (len > digits) {
+    *s++ = fill;
+    --len;
+  }
+
+  while (len > 0) {
+    uint32_t nib = n & 0xf;
+    n = n >> 4;
+    if (nib > 9) {
+      nib += (97 - 10);
+    } else {
+      nib += (48 - 0);
+    }
+
+    s[--len] = nib;
+  }
+
+  return ret;
+}
diff --git a/text_editor/unparse.hpp b/text_editor/unparse.hpp
new file mode 100644
index 0000000..2a3785f
--- /dev/null
+++ b/text_editor/unparse.hpp
@@ -0,0 +1,8 @@
+#pragma once
+
+#include <stdint.h>
+
+int unparse_base10_unsigned(char * s, uint32_t n, int len, char fill);
+int unparse_base10(char * s, int32_t n, int len, char fill);
+int unparse_base10_64(char * s, int64_t n, int len, char fill);
+int unparse_base16(char * s, uint32_t n, int len, char fill);
diff --git a/text_editor/viewport_window.hpp b/text_editor/viewport_window.hpp
index 76970d8..18c1949 100644
--- a/text_editor/viewport_window.hpp
+++ b/text_editor/viewport_window.hpp
@@ -2,6 +2,8 @@
 
 #include <cstdint>
 
+#include "font/font.h"
+
 struct viewport_window {
   int32_t first_line;
   struct {
@@ -12,11 +14,11 @@ struct viewport_window {
   } box;
 };
 
-inline void viewport_init_fullscreen(viewport_window& window)
+static inline void viewport_init_fullscreen(viewport_window& window, const font * font)
 {
   window.first_line = 0;
   window.box.x0 = 10;
   window.box.y0 = 20;
   window.box.x1 = 640 - 10;
-  window.box.y1 = 480 - 20;
+  window.box.y1 = 480 - (font->face_metrics.height >> 6) * 2;
 }