The Microsoft SoftCard for the Apple II: getting two processors to share the same memory

We talked about the Z80 SoftCard, Microsoft's first hardware product, back in 2023, but thanks to Raymond Chen and Nicole Branagan, we've got some more insights.

TheMicrosoft Z-80 SoftCardwas a plug-in expansion card for the Apple II that added the ability to run CP/M software. According to Wikipedia, it was Microsoft's first hardware product and in 1980 was the single largest revenue source for the company.

Raymond Chen at The Old New Thing

And Chen links to an article by Branagan from 2020, which goes into even more detail.

So there I was, very happy with myApple ][_plus. But then I saw someone on the internet post, and it seems that my Apple is an overpriced box with a toy microcontroller for a CPU, whilerealcomputers use an Intel 8080, 8085 or Zilog Z80 to run something called CP/M"... but I've already spent so much money on the Apple, so can I turn it into a real computer?

Nicole Branagan

I have a soft spot for this particular subgenre of hardware - add-in cards that allow you to run an entirely different architecture inside your computer - and soon, I'll be diving into a particularly capable example here on OSNews.