diff --git a/README.md b/README.md
index 879e32f..90920e9 100644
--- a/README.md
+++ b/README.md
@@ -72,7 +72,8 @@ display.
   3.7 [Class Textbox](./README.md#37-class-textbox) Scrolling text display.  
  4. [ESP8266](./README.md#4-esp8266) This can work. Contains information on
  minimising the RAM and flash footprints of the GUI.  
-[Appendix 1 Freezing bytecode](./README.md#appendix-1-freezing-bytecode) Optional way to save RAM.
+[Appendix 1 Freezing bytecode](./README.md#appendix-1-freezing-bytecode) Optional way to save RAM.  
+[Appendix 2 Round displays](./README.md#appendix-2-round-displays) Alternative hardware check script.
 
 #### [Supported displays](./DISPLAYS.md)
 
@@ -295,6 +296,7 @@ Demos for larger displays.
  * `asnano_sync.py` Two Pyboard specific demos using the GUI with `asyncio`.
  * `asnano.py` Could readily be adapted for other targets.
  * `tbox.py` Demo `Textbox` class. Cross-platform.
+ * `round.py` Demo for 240*240 circular displays.
 
 Demos for ePaper displays:
  * `epd_async.py` Demo of asynchronous code on an eInk display. Needs a large display.
@@ -405,6 +407,9 @@ ssd.rect(0, 0, 15, 15, RED)  # Red square at top left
 ssd.rect(ssd.width -15, ssd.height -15, 15, 15, BLUE)  # Blue square at bottom right
 refresh(ssd)
 ```
+For round displays please see
+[Appendix 2 Round displays](./README.md#appendix-2-round-displays) for a
+suitable hardware check script.
 
 ###### [Contents](./README.md#contents)
 
@@ -455,7 +460,7 @@ wri = CWriter(ssd, arial10, GREEN, BLACK, verbose=False)  # Colors are defaults
 wri.set_clip(True, True, False)
 ```
 
-Initialisation of monochorome text display follows. For each font a `Writer` instance
+Initialisation of monochrome text display follows. For each font a `Writer` instance
 is created:
 ```python
 from gui.core.writer import Writer  # Renders color text
@@ -1023,3 +1028,23 @@ as I have experienced problems freezing display drivers - but feel free to
 experiment.
 
 ###### [Contents](./README.md#contents)
+
+## Appendix 2 Round displays
+
+The normal test script is unsuitable as the rectangles are off-screen. Please
+paste this at the REPL to verify hardware and display orientation:
+```Python
+from color_setup import ssd  # Create a display instance
+from gui.core.colors import RED, BLUE, GREEN
+from gui.core.nanogui import refresh, circle
+refresh(ssd, True)  # Initialise and clear display.
+ssd.fill(0)
+w = ssd.width
+ssd.line(0, 0, w - 1, w - 1, GREEN)  # Green diagonal corner-to-corner
+offs = round(0.29289 * w / 2)
+ssd.rect(offs, offs, 15, 15, RED)  # Red square at top left
+ssd.rect(w - offs - 15, w - offs - 15, 15, 15, BLUE)  # Blue square at bottom right
+circle(ssd, 119, 119, 119, GREEN)
+refresh(ssd)
+```
+###### [Contents](./README.md#contents)
diff --git a/drivers/gc9a01/gc9a01.py b/drivers/gc9a01/gc9a01.py
new file mode 100644
index 0000000..8df05db
--- /dev/null
+++ b/drivers/gc9a01/gc9a01.py
@@ -0,0 +1,214 @@
+# gc9a01 nano-gui driver for gc9a01 displays
+# Default args are for a 240*240 (typically circular) display
+
+# Copyright (c) Peter Hinch 2024
+# Released under the MIT license see LICENSE
+
+from time import sleep_ms
+import gc
+import framebuf
+import asyncio
+from drivers.boolpalette import BoolPalette
+
+# Initialisation ported from Russ Hughes' C driver
+# https://github.com/russhughes/gc9a01_mpy/blob/main/src/gc9a01.h
+# https://github.com/russhughes/gc9a01_mpy/blob/main/src/gc9a01.c
+# Based on a ST7789 C driver: https://github.com/devbis/st7789_mpy
+# Many registers are undocumented. Lines initialising them are commented "?"
+# in cases where initialising them seems to have no effect.
+
+# Datasheet 7.3.4 allows scl <= 100MHz
+# Waveshare touch board https://www.waveshare.com/wiki/1.28inch_Touch_LCD has CST816S touch controller
+# Touch controller uses I2C
+
+# Portrait mode
+@micropython.viper
+def _lcopy(dest: ptr16, source: ptr8, lut: ptr16, length: int):
+    # rgb565 - 16bit/pixel
+    n: int = 0
+    x: int = 0
+    while length:
+        c = source[x]  # Source byte holds two 4-bit colors
+        dest[n] = lut[c >> 4]  # current pixel
+        n += 1
+        dest[n] = lut[c & 0x0F]  # next pixel
+        n += 1
+        x += 1
+        length -= 1
+
+
+class GC9A01(framebuf.FrameBuffer):
+
+    lut = bytearray(32)  # Color LUT holds all possible 16-bit colors
+
+    # Convert r, g, b in range 0-255 to a 16 bit colour value
+    # LS byte goes into LUT offset 0, MS byte into offset 1
+    # Same mapping in linebuf so LS byte is shifted out 1st
+    # GC9A01 expects RGB order. 8 bit register writes require padding
+    @classmethod
+    def rgb(cls, r, g, b):
+        return (r & 0xF8) | ((g & 0xE0) >> 5) | ((g & 0x1C) << 11) | ((b & 0xF8) << 5)
+
+    def __init__(
+        self,
+        spi,
+        cs,
+        dc,
+        rst,
+        height=240,
+        width=240,
+        lscape=False,
+        usd=False,
+        mirror=False,
+        init_spi=False,
+    ):
+        self._spi = spi
+        self._cs = cs
+        self._dc = dc
+        self._rst = rst
+        self.height = height  # Logical dimensions for GUIs
+        self.width = width
+        self._spi_init = init_spi
+        mode = framebuf.GS4_HMSB
+        self.palette = BoolPalette(mode)
+        gc.collect()
+        buf = bytearray(height * width // 2)  # Frame buffer
+        self._mvb = memoryview(buf)
+        super().__init__(buf, width, height, mode)
+        self._linebuf = bytearray(width * 2)  # Line buffer (16-bit colors)
+
+        # Hardware reset
+        self._rst(0)
+        sleep_ms(50)
+        self._rst(1)
+        sleep_ms(50)
+        if self._spi_init:  # A callback was passed
+            self._spi_init(spi)  # Bus may be shared
+        self._lock = asyncio.Lock()
+        sleep_ms(100)
+        self._wcd(b"\x2a", int.to_bytes(width - 1, 4, "big"))
+        # Default page address start == 0 end == 0xEF (239)
+        self._wcd(b"\x2b", int.to_bytes(height - 1, 4, "big"))  # SET_PAGE ht
+        # **** Start of opaque chip setup ****
+        self._wcmd(b"\xEF")  # Inter register enable 2
+        self._wcd(b"\xEB", b"\x14")  # ?
+        self._wcmd(b"\xFE")  # Inter register enable 1
+        self._wcmd(b"\xEF")  # Inter register enable 2
+        self._wcd(b"\xEB", b"\x14")  # ?
+        self._wcd(b"\x84", b"\x40")  # ?
+        self._wcd(b"\x85", b"\xFF")  # ?
+        self._wcd(b"\x87", b"\xFF")  # ?
+        self._wcd(b"\x86", b"\xFF")  # ?
+        self._wcd(b"\x88", b"\x0A")  # ?
+        self._wcd(b"\x89", b"\x21")  # ?
+        self._wcd(b"\x8A", b"\x00")  # ?
+        self._wcd(b"\x8B", b"\x80")  # ?
+        self._wcd(b"\x8C", b"\x01")  # ?
+        self._wcd(b"\x8D", b"\x01")  # ?
+        self._wcd(b"\x8E", b"\xFF")  # ?
+        self._wcd(b"\x8F", b"\xFF")  # ?
+        self._wcd(b"\xB6", b"\x00\x00")  # Display function control
+        self._wcd(b"\x3A", b"\x55")  # COLMOD
+        self._wcd(b"\x90", b"\x08\x08\x08\x08")  # ?
+        self._wcd(b"\xBD", b"\x06")  # ?
+        self._wcd(b"\xBC", b"\x00")  # ?
+        self._wcd(b"\xFF", b"\x60\x01\x04")  # ?
+        self._wcd(b"\xC3", b"\x13")  # Vreg1a voltage Control
+        self._wcd(b"\xC4", b"\x13")  # Vreg1b voltage Control
+        self._wcd(b"\xC9", b"\x22")  # Vreg2a voltage Control
+        self._wcd(b"\xBE", b"\x11")  # ?
+        self._wcd(b"\xE1", b"\x10\x0E")  # ?
+        self._wcd(b"\xDF", b"\x21\x0c\x02")  # ?
+        self._wcd(b"\xF0", b"\x45\x09\x08\x08\x26\x2A")  # Gamma
+        self._wcd(b"\xF1", b"\x43\x70\x72\x36\x37\x6F")  # Gamma
+        self._wcd(b"\xF2", b"\x45\x09\x08\x08\x26\x2A")  # Gamma
+        self._wcd(b"\xF3", b"\x43\x70\x72\x36\x37\x6F")  # Gamma
+        self._wcd(b"\xED", b"\x1B\x0B")  # ?
+        self._wcd(b"\xAE", b"\x77")  # ?
+        self._wcd(b"\xCD", b"\x63")  # ?
+        self._wcd(b"\x70", b"\x07\x07\x04\x0E\x0F\x09\x07\x08\x03")  # ?
+        self._wcd(b"\xE8", b"\x34")  # Frame rate / dot inversion
+        self._wcd(b"\x62", b"\x18\x0D\x71\xED\x70\x70\x18\x0F\x71\xEF\x70\x70")  # ?
+        self._wcd(b"\x63", b"\x18\x11\x71\xF1\x70\x70\x18\x13\x71\xF3\x70\x70")  # ?
+        self._wcd(b"\x64", b"\x28\x29\xF1\x01\xF1\x00\x07")  # ?
+        self._wcd(b"\x66", b"\x3C\x00\xCD\x67\x45\x45\x10\x00\x00\x00")  # Undoc but needed
+        self._wcd(b"\x67", b"\x00\x3C\x00\x00\x00\x01\x54\x10\x32\x98")  # Undoc but needed
+        self._wcd(b"\x74", b"\x10\x85\x80\x00\x00\x4E\x00")  # ?
+        self._wcd(b"\x98", b"\x3e\x07")  # ?
+        self._wcmd(b"\x35")  # Tearing effect line on
+        self._wcmd(b"\x21")  # Display inversion on ???
+        self._wcmd(b"\x11")
+        sleep_ms(120)
+        # *************************
+
+        # madctl reg 0x36 p127 6.2.18. b0-2 == 0. b3: color output BGR RGB/
+        # b4 == 0
+        # d5 row/col exchange
+        # d6 col address order
+        # d7 row address order
+        if lscape:
+            madctl = 0x28 if usd else 0xE8  # RGB landscape mode
+        else:
+            madctl = 0x48 if usd else 0x88  # RGB portrait mode
+        if mirror:
+            madctl ^= 0x80
+        self._wcd(b"\x36", madctl.to_bytes(1, "big"))  # MADCTL: RGB portrait mode
+        self._wcmd(b"\x29")  # display on
+
+    # Write a command.
+    def _wcmd(self, command):
+        self._dc(0)
+        self._cs(0)
+        self._spi.write(command)
+        self._cs(1)
+
+    # Write a command followed by a data arg.
+    def _wcd(self, command, data):
+        self._dc(0)
+        self._cs(0)
+        self._spi.write(command)
+        self._cs(1)
+        self._dc(1)
+        self._cs(0)
+        self._spi.write(data)
+        self._cs(1)
+
+    # @micropython.native  # Made almost no difference to timing
+    def show(self):  # Physical display is in portrait mode
+        clut = GC9A01.lut
+        lb = self._linebuf
+        buf = self._mvb
+        if self._spi_init:  # A callback was passed
+            self._spi_init(self._spi)  # Bus may be shared
+        self._wcmd(b"\x2c")  # WRITE_RAM
+        self._dc(1)
+        self._cs(0)
+        wd = self.width // 2
+        ht = self.height
+        for start in range(0, wd * ht, wd):  # For each line
+            _lcopy(lb, buf[start:], clut, wd)  # Copy and map colors
+            self._spi.write(lb)
+        self._cs(1)
+
+    async def do_refresh(self, split=4):
+        async with self._lock:
+            lines, mod = divmod(self.height, split)  # Lines per segment
+            if mod:
+                raise ValueError("Invalid do_refresh arg.")
+            clut = GC9A01.lut
+            lb = self._linebuf
+            buf = self._mvb
+            self._wcmd(b"\x2c")  # WRITE_RAM
+            self._dc(1)
+            wd = self.width // 2
+            line = 0
+            for _ in range(split):  # For each segment
+                if self._spi_init:  # A callback was passed
+                    self._spi_init(self._spi)  # Bus may be shared
+                self._cs(0)
+                for start in range(wd * line, wd * (line + lines), wd):  # For each line
+                    _lcopy(lb, buf[start:], clut, wd)  # Copy and map colors
+                    self._spi.write(lb)
+                line += lines
+                self._cs(1)  # Allow other tasks to use bus
+                await asyncio.sleep_ms(0)
diff --git a/drivers/ili93xx/ili9341.py b/drivers/ili93xx/ili9341.py
index bd78847..def8194 100644
--- a/drivers/ili93xx/ili9341.py
+++ b/drivers/ili93xx/ili9341.py
@@ -87,12 +87,10 @@ class ILI9341(framebuf.FrameBuffer):
         self._wcd(b"\xb6", b"\x08\x82\x27")  # DFUNCTR
         self._wcd(b"\xf2", b"\x00")  # ENABLE3G Enable 3 gamma ctrl
         self._wcd(b"\x26", b"\x01")  # GAMMASET Gamma curve selected
-        self._wcd(
-            b"\xe0", b"\x0F\x31\x2B\x0C\x0E\x08\x4E\xF1\x37\x07\x10\x03\x0E\x09\x00"
-        )  # GMCTRP1
-        self._wcd(
-            b"\xe1", b"\x00\x0E\x14\x03\x11\x07\x31\xC1\x48\x08\x0F\x0C\x31\x36\x0F"
-        )  # GMCTRN1
+        # GMCTRP1
+        self._wcd(b"\xe0", b"\x0F\x31\x2B\x0C\x0E\x08\x4E\xF1\x37\x07\x10\x03\x0E\x09\x00")
+        # GMCTRN1
+        self._wcd(b"\xe1", b"\x00\x0E\x14\x03\x11\x07\x31\xC1\x48\x08\x0F\x0C\x31\x36\x0F")
         self._wcmd(b"\x11")  # SLPOUT Exit sleep
         sleep_ms(100)
         self._wcmd(b"\x29")  # DISPLAY_ON
diff --git a/drivers/st7789/st7789_4bit.py b/drivers/st7789/st7789_4bit.py
index eca43b6..13756f2 100644
--- a/drivers/st7789/st7789_4bit.py
+++ b/drivers/st7789/st7789_4bit.py
@@ -1,7 +1,7 @@
 # st7789.py Driver for ST7789 LCD displays for nano-gui
 
 # Released under the MIT License (MIT). See LICENSE.
-# Copyright (c) 2021 Peter Hinch, Ihor Nehrutsa
+# Copyright (c) 2021-2024 Peter Hinch, Ihor Nehrutsa
 
 # Tested displays:
 # Adafruit 1.3" 240x240 Wide Angle TFT LCD Display with MicroSD - ST7789
@@ -39,13 +39,16 @@ WAVESHARE_13 = (0, 0, 16)  # Waveshare 1.3" 240x240 LCD contributed by Aaron Mit
 @micropython.viper
 def _lcopy(dest: ptr16, source: ptr8, lut: ptr16, length: int):
     # rgb565 - 16bit/pixel
-    n = 0
-    for x in range(length):
+    n: int = 0
+    x: int = 0
+    while length:
         c = source[x]
         dest[n] = lut[c >> 4]  # current pixel
         n += 1
         dest[n] = lut[c & 0x0F]  # next pixel
         n += 1
+        x += 1
+        length -= 1
 
 
 class ST7789(framebuf.FrameBuffer):