Wonky French Flag

This is an example ZX Spectrum program which produces a wonky French flag.

Usage

Clone this git repository
Change into the directory
Run code . to bring up VSCode
Agree to "Reopen in container"
Wait for the devcontainer to download and initialise
Build the project with make
Open the myprog.sna file in your favourite Spectrum emulator
Recoil at flag wonkiness
Open main.asm in the VSCode editor and have a quick read
Select "Run and Debug" from the bar on the far left
In the drop down bar at the top, select "Simulator - ZX48K Spectrum"
Press the "Start Debugging" green arrow to the left of the dropdown list
Select the "Continue" arrow from the wee icon menu which has appeared at the top of the screen
Recoil again at the wonky flag
Stop debugging by pressing the square at the far right of the wee icon menu
Go back to the main.asm file
Left click on the space to the left of the line number at line 25
A little red breakpoint blob should have appeared. You can toggle this by clicking on it
Start debugging again
Press "Continue" arrow as before
The debugger will stop the program running at the breakpoint
Keep pressing the "Step into" downwards arrow on the wee icon bar
Note what is happening to the registers on the left and the screen on the right
Watch the red stripe getting painted
Have a moment of revelation about how you're going to fix this
Stop the debugger
Edit main.asm to fix the bug
Remember to save the file and run make again to rebuild the program
Remove the breakpoint on line 25
Run in the debugger again
Marvel at the lovely flag