diff --git a/SSD1306/SSD1306Ascii.cpp b/SSD1306/SSD1306Ascii.cpp
index 0a436b2..95bfaf0 100644
--- a/SSD1306/SSD1306Ascii.cpp
+++ b/SSD1306/SSD1306Ascii.cpp
@@ -1,7 +1,5 @@
-/* Arduino SSD1306Ascii Library
- * Copyright (C) 2015 by William Greiman
- *
- * This file is part of the Arduino SSD1306Ascii Library
+/* Based on Arduino SSD1306Ascii Library, Copyright (C) 2015 by William Greiman
+ * Modifications (C) 2021 Neil McKechnie
  *
  * This Library is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -29,10 +27,8 @@ void SSD1306Ascii::clear(uint8_t c0, uint8_t c1, uint8_t r0, uint8_t r1) {
 
   for (uint8_t r = r0; r <= r1; r++) {
     setCursor(c0, r);
-    for (uint8_t c = c0; c <= c1; c++) {
-      // Ensure clear() writes zero. result is (m_invertMask^m_invertMask).
-      ssd1306WriteRamBuf(m_invertMask);
-    }
+    for (uint8_t c = c0; c <= c1; c++)
+      ssd1306WriteRamBuf(0);
   }
   setCursor(c0, r0);
 }
@@ -76,11 +72,6 @@ void SSD1306Ascii::setCursor(uint8_t col, uint8_t row) {
 //------------------------------------------------------------------------------
 void SSD1306Ascii::setFont(const uint8_t* font) {
   m_font = font;
-  m_letterSpacing = 1;
-  m_fontFirstChar = readFontByte(m_font + FONT_FIRST_CHAR);
-  m_fontCharCount = readFontByte(m_font + FONT_CHAR_COUNT);  
-  m_fontHeight = readFontByte(m_font + FONT_HEIGHT);
-  m_fontWidth = readFontByte(m_font + FONT_WIDTH);
 }
 //------------------------------------------------------------------------------
 void SSD1306Ascii::setRow(uint8_t row) {
@@ -92,14 +83,14 @@ void SSD1306Ascii::setRow(uint8_t row) {
 //------------------------------------------------------------------------------
 void SSD1306Ascii::ssd1306WriteRam(uint8_t c) {
   if (m_col < m_displayWidth) {
-    writeDisplay(c^m_invertMask, SSD1306_MODE_RAM);
+    writeDisplay(c, SSD1306_MODE_RAM);
     m_col++;
   }
 }
 //------------------------------------------------------------------------------
 void SSD1306Ascii::ssd1306WriteRamBuf(uint8_t c) {
   if (m_col < m_displayWidth) {
-    writeDisplay(c^m_invertMask, SSD1306_MODE_RAM_BUF);
+    writeDisplay(c, SSD1306_MODE_RAM_BUF);
     m_col++;
   }
 }
@@ -108,30 +99,21 @@ size_t SSD1306Ascii::write(uint8_t ch) {
   if (!m_font) {
     return 0;
   }
-  uint8_t w = readFontByte(m_font + FONT_WIDTH);
-  uint8_t h = readFontByte(m_font + FONT_HEIGHT);
-  uint8_t nr = (h + 7)/8;
-  uint8_t first = readFontByte(m_font + FONT_FIRST_CHAR);
-  uint8_t count = readFontByte(m_font + FONT_CHAR_COUNT);
   const uint8_t* base = m_font + FONT_WIDTH_TABLE;
+  const uint8_t letterSpacing = 1;
+  uint8_t fontFirstChar = readFontByte(m_font + FONT_FIRST_CHAR);
+  uint8_t fontCharCount = readFontByte(m_font + FONT_CHAR_COUNT); 
+  uint8_t fontWidth = readFontByte(m_font + FONT_WIDTH);
 
-  if (ch < first || ch >= (first + count)) return 0;
-  ch -= first;
-  uint8_t s = letterSpacing();
-  // Fixed width font.
-  base += nr*w*ch;
-  uint8_t scol = m_col;
-  for (uint8_t r = 0; r < nr; r++) {
-    if (r) {
-      setCursor(scol, m_row + 1);
-    }
-    for (uint8_t c = 0; c < w; c++) {
-      uint8_t b = readFontByte(base + c + r*w);
-      ssd1306WriteRamBuf(b);
-    }
-    for (uint8_t i = 0; i < s; i++) {
-      ssd1306WriteRamBuf(0);
-    }
+  if (ch < fontFirstChar || ch >= (fontFirstChar + fontCharCount)) return 0;
+  ch -= fontFirstChar;
+  base += fontWidth * ch;
+  for (uint8_t c = 0; c < fontWidth; c++) {
+    uint8_t b = readFontByte(base + c);
+    ssd1306WriteRamBuf(b);
+  }
+  for (uint8_t i = 0; i < letterSpacing; i++) {
+    ssd1306WriteRamBuf(0);
   }
   flushDisplay();
   return 1;
diff --git a/SSD1306/SSD1306Ascii.h b/SSD1306/SSD1306Ascii.h
index 6225efe..c178997 100644
--- a/SSD1306/SSD1306Ascii.h
+++ b/SSD1306/SSD1306Ascii.h
@@ -1,7 +1,5 @@
-/* Arduino SSD1306Ascii Library
- * Copyright (C) 2015 by William Greiman
- *
- * This file is part of the Arduino SSD1306Ascii Library
+/* Based on Arduino SSD1306Ascii Library, Copyright (C) 2015 by William Greiman
+ * Modifications (C) 2021 Neil McKechnie
  *
  * This Library is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -27,7 +25,7 @@
 #include "SSD1306init.h"
 #include "fonts/allFonts.h"
 //------------------------------------------------------------------------------
-/** SSD1306Ascii version */
+/** SSD1306Ascii version basis */
 #define SDD1306_ASCII_VERSION 1.3.0
 //------------------------------------------------------------------------------
 // Configuration options.
@@ -124,22 +122,6 @@ class SSD1306Ascii : public Print {
    * @return The display width in pixels.
    */
   inline uint8_t displayWidth() const {return m_displayWidth;}
-  /**
-   * @return The current font pointer.
-   */
-  const uint8_t* font() const {return m_font;}
-  /**
-   * @return The count of characters in a font.
-   */
-  inline uint8_t fontCharCount() const {return m_fontCharCount;};
-  /**
-   * @return The first character in a font.
-   */
-  inline char fontFirstChar() const {return m_fontFirstChar;};
-  /**
-   * @return The current font height in pixels.
-   */
-  inline uint8_t fontHeight() const {return m_fontHeight;};
   /**
    * @brief Set the cursor position to (0, 0).
    */
@@ -150,26 +132,6 @@ class SSD1306Ascii : public Print {
    * @param[in] dev A display initialization structure.
    */
   void init(const DevType* dev);
-  /**
-   * @brief Set pixel mode for for entire display.
-   *
-   * @param[in] invert Inverted display if true or normal display if false.
-   */
-  void invertDisplay(bool invert);
-  /**
-   * @return invert mode.
-   */
-  inline bool invertMode() const {return !!m_invertMask;}
-  /**
-   * @brief Set invert mode for write/print.
-   *
-   * @param[in] mode Invert pixels if true and use normal mode if false.
-   */
-  inline void setInvertMode(bool mode) {m_invertMask = mode ? 0XFF : 0;}
-  /**
-   * @return letter-spacing in pixels with magnification factor.
-   */
-  inline uint8_t letterSpacing() const {return m_letterSpacing;}
   /**
    * @return the current row number with eight pixels to a row.
    */
@@ -245,14 +207,6 @@ class SSD1306Ascii : public Print {
   uint8_t m_displayWidth;   // Display width.
   uint8_t m_displayHeight;  // Display height.
   uint8_t m_colOffset;      // Column offset RAM to SEG.
-  uint8_t m_letterSpacing;  // Letter-spacing in pixels.
   const uint8_t* m_font = nullptr;  // Current font.
-  uint8_t m_invertMask = 0;  // font invert mask
-
-  char m_fontFirstChar;
-  uint8_t m_fontCharCount;
-  uint8_t m_fontHeight;
-  uint8_t m_fontWidth;
-
 };
 #endif  // SSD1306Ascii_h