A few important changes have happened recently.

-=-=-

1. The Minus Bug
A curious bug plaguing the language since its inception, I'm about 95% convinced that it no longer exists.
Of course, I could be wrong, and it's hiding away in places I can't conceive, but .. I'm pretty sure it's gone.

2. And/Or Fixes
Ands and Ors were "almost" working properly.
Now they "should" be working properly!!

3. Not
I struggled with Not for quite a while, but now I think I've got the basics down!
It might not be sturdy, though, so do be careful.

4. BODMAS!
Just when I was happy with BODMAS, along comes a Mandelbrot generator.
Seems I was separating the DM and AS bits.. Add THEN Subtract, but it should be Add WITH Subtract. And the same for Divide and Multiply. Together, not apart.
I've fixed this, and it seems to be working fine.

For all of the above, extreme apologies if I've broken your code.
I've tried my best not to, but these are fairly deep commands, and they make up a sizeable chunk of how things fundamentally work in the language.

Meanwhile...

Over on YouTube, Matt Heffernan did a little test of a Mandelbrot generator on various versions of BASIC.

View on YouTube

I decided to give it a whirl in GotoJSE, to see how it'd turns out.
The C64 result is astoundingly true to how it looks on his video!
If you switch it to ZX Spectrum, it's not as close, but I put that down to the colour palette.

// Matt Heffernan's Mandlebrot Example
// https://youtu.be/DC5wi6iv9io

// copied by Jayenkai
// https://GotoJSE.com/HgjhB48c.BAS 

// Created 2021/08/20

Graphics 32,22,3
UsePalette "c64"

MaxIt=14

For py=0 to ScreenHeight()
yz=py*2/ScreenHeight()-1

For px=0 to ScreenWidth()
xz=px*3.5/ScreenWidth()-2.5

x=0:y=0
For i=0 to MaxIt
	if x*x+y*y>4 then break
	xt=(x*x-y*y)+xz
	y=2*x*y+yz
	x=xt
Next

i=i-1
Ink i
Plot px,py
Next
Next

1920x1080 edition
Feel free to tweak the mandelbrot code to make whatever size you like, but it's not exactly super-fast at high resolutions!