Microsoft’s original source code

I've written an Intel 8080 emulator that was portable between Dec10/VAX/IBM VM CMS. That was easy - the 8080 can be done quite simply with a 256 value switch - I did mine in FORTRAN77.

Writing a BASIC interpreter, with floating point, is much harder. Gates, Allen and other collaborators BASIC was pretty damned good.

Fun facts, according to Jobs for some unknown reasons Wozniak refused to add floating point support to Apple Basic thus they had to license BASIC with floating point numbers from Microsoft [1].

[1] Bill & Steve (Jobs!) reminisce about floating point BASIC:

https://devblogs.microsoft.com/vbteam/bill-steve-jobs-remini...

Writing a floating point emulator (I've done it) is not too hard. First, write it in a high level language, and debug the algorithm. Then hand-assembling it is not hard.

What is hard is skipping the high level language step, and trying to do it in assembler in one step.

I've never understood floating point :-)