Update README.md

README.md

@@ -1,3 +1,6 @@
+Sure! Here’s the **entire document in a single Markdown block** ready to copy:
+
+````markdown
 # Colour Maximite 2 - CSUB Example and ARM Cortex-M7 Embedded Code
 
 This document demonstrates how to embed ARM Cortex-M7 machine code directly into your BASIC program on the Colour Maximite 2 using the `CSUB` directive. It covers a minimal example, explains the embedded machine code, and provides detailed instructions on writing, compiling, and embedding ARM Thumb-2 assembly or C routines.
@@ -15,9 +18,9 @@ According to the Colour Maximite 2 user manual:
 > hex [[ hex[…]]  
 > `END CSUB`  
 >  
-> Defines the binary code for an embedded machine code program module written in C or ARM assembler. The module will appear in MMBasic as the command 'name' and can be used in the same manner as a built-in command.
+> Defines the binary code for an embedded machine code program module written in C or ARM assembler. The module will appear in MMBasic as the command `name` and can be used in the same manner as a built-in command.
 
-Multiple embedded routines can be used in a program, each defining a different module with a different name. The first hex word is a 32-bit word which is the offset in bytes from the start of the CSUB to the entry point of the embedded routine (usually the function `main()`). The following hex words are the compiled binary code for the module.
+Multiple embedded routines can be used in a program, each defining a different module with a unique name. The first hex word is a 32-bit word representing the offset in bytes from the start of the CSUB to the entry point of the embedded routine (usually the function `main()`). The following hex words are the compiled binary code for the module.
 
 ---
 
@@ -32,34 +35,42 @@ simple()
 
 PRINT "Returned successfully"
 ````
+
 ![Description](IMG_0019.JPG)
+
 ---
 
 ## What Does This Thumb-2 Machine Code Do?
 
 ### `CSUB simple`
-- Starts the definition of a machine-code subroutine named `simple`.  
+
-- Tells the BASIC runtime that the following hex words are compiled machine code to execute when `simple()` is called.
+* Starts the definition of a machine-code subroutine named `simple`.
+* Tells the BASIC runtime that the following hex words are compiled machine code to execute when `simple()` is called.
 
 ### `00000000`
-- The entry point offset for the CSUB.  
+
-- A value of `0` indicates execution starts immediately at the next word.  
+* The entry point offset for the CSUB.
-- This word is metadata only; it is **not executed** as machine code.
+* A value of `0` indicates execution starts immediately at the next word.
+* This word is metadata only; it is **not executed** as machine code.
 
 ### `00004770`
-- Encodes the Thumb instruction `BX LR` (Branch to Link Register).  
+
-- This instruction **returns immediately** from the subroutine to BASIC.
+* Encodes the Thumb instruction `BX LR` (Branch to Link Register).
+* This instruction **returns immediately** from the subroutine to BASIC.
 
 ### `END CSUB`
-- Marks the end of the CSUB block.  
+
-- Signals that the machine code definition is complete, and BASIC execution continues normally.
+* Marks the end of the CSUB block.
+* Signals that the machine code definition is complete, and BASIC execution continues normally.
 
 ### `simple()`
-- Calls the subroutine `simple`.  
-- Execution jumps to the CSUB, reads the entry point offset, executes the `BX LR` instruction, and immediately returns.
 
-### `PRINT " Returned successfully"`
+* Calls the subroutine `simple`.
-- Prints a message to the BASIC console to indicate the subroutine returned successfully.  
+* Execution jumps to the CSUB, reads the entry point offset, executes the `BX LR` instruction, and immediately returns.
+
+### `PRINT "Returned successfully"`
+
+* Prints a message to the BASIC console to indicate the subroutine returned successfully.
 
 ---
 
@@ -71,18 +82,18 @@ PRINT "Returned successfully"
 .global simple
 
 simple:
-    movs r0, #42       @ Load immediate value 42 into register R0
+    bx lr      @ Return immediately
-    bx lr              @ Return from subroutine
 ```
 
 ### Explanation
 
 * `.syntax unified`: Use modern unified ARM assembler syntax.
 * `.thumb`: Assemble for the Thumb instruction set used by Cortex-M7.
-* `.global main`: Declare the `main` symbol as global (entry point).
+* `.global simple`: Declare the `simple` symbol as global (entry point).
-* `movs r0, #42`: Move the immediate value 42 into register `R0` (standard register for function return values).
 * `bx lr`: Branch to the address stored in the Link Register (`LR`), returning control to the caller.
 
+> Note: In this minimal example, no values are returned to BASIC.
+
 ---
 
 ## How to Compile, Link, and Extract Binary
@@ -113,7 +124,7 @@ arm-none-eabi-gcc -mcpu=cortex-m7 -mthumb -nostartfiles -Wl,-Ttext=0x0 -o main.e
 ```
 
 * `-nostartfiles`: Avoid linking standard startup code.
-* `-Ttext=0x0`: Load address set to 0.
+* `-Ttext=0x0`: Set load address to 0.
 
 ### Step 4: Extract Raw Binary
 
@@ -165,9 +176,9 @@ CSUB MySub integer, integer, string
 ```
 
 * Up to 10 arguments are supported.
-* Variables or arrays passed are pointers to their data. This allows embedded routines to modify passed data directly.
+* Variables or arrays passed are pointers to their data, allowing embedded routines to modify passed data directly.
 * Constants and expressions are passed as pointers to temporary memory containing their values.
-* Remember to call `routinechecks()` regularly in longer-running routines to keep USB and watchdog timers active, or keep your routine execution within a few milliseconds.
+* For longer-running routines, call `routinechecks()` regularly to keep USB and watchdog timers active, or keep routine execution under a few milliseconds.
 
 ---
 
@@ -177,10 +188,17 @@ CSUB MySub integer, integer, string
 * Compile C routines similarly, specifying `-mcpu=cortex-m7 -mthumb` in compiler flags.
 * Place CSUB blocks anywhere in your BASIC code; MMBasic will skip over them during execution.
 * Each hex word must be exactly eight hex digits and separated by spaces or new lines.
-* Errors in formatting or hex data will cause runtime errors in MMBasic.
+* Formatting errors or incorrect hex data will cause runtime errors in MMBasic.
 
 ---
 
 ## License
 
 This document and any accompanying code are released under the MIT License.
+
+```
+
+This is one clean block you can copy directly into any Markdown editor.  
+
+If you want, I can **also add a clickable table of contents** inside this single block for easier navigation. Do you want me to do that?
+```