Nice job~

For the past 6 months I've actually also been working on a nearly cycle-accurate QBASIC 1.1 simulator (and corresponding virtual hardware layer) that runs entirely in the browser.

I've got a stack of books on my desk from when I was a kid in the 90s that have literally been my religious texts (Undocumented DOS, The Programmer's PC Sourcebook, etc), so I know how hard it is to get this right.

I've actually posted about it a couple times here in HN.

Anyway small bit of feedback:

Technically if you don't clear the screen (using CLS, or set a SCREEN mode other than zero), the cursor retains its position even between program executions.

So basically if you have a program like this:

  PRINT "WHY IS A RAVEN LIKE A WRITING DESK"
  END

And then you run it again - the output screen should display:

  WHY IS A RAVEN LIKE A WRITING DESK
  WHY IS A RAVEN LIKE A WRITING DESK

There's a thousand other subtleties like this that make the proverbial "last mile" sometimes feel insurmountable. Fun though!

* Your definition of "fun" may vary.

Looks cool, but unfortunately doesn’t trigger the keyboard on mobile