Advanced Mac Substitute is an API-level reimplementation of 1980s-era Mac OS

This is quite the feat. I’d love to know more about the process to make this, the motivation, how much time was spent, etc.

related discussion https://news.ycombinator.com/item?id=40338443

I'm guessing they reimplemented the toolbox at the TRAP level (most MacOS calls at the time were accessed through the 68K TRAP instruction).

So, rather than emulating hardware to run native ROMs, they "simply" reimplemented the ROMs.

A friend of mine did this at another level. He basically rewrote the bulk of the toolbox as a C library so that the company, who had a Mac application, could port it to run on a PC, while sharing the source code.

This was before Windows, and it worked! Launched it from DOS, takes over the entire screen. He didn't copy the Mac look and feel. Instead he used OpenLook for his gadgets and what not (since it was, you know, "open").

But he rewrote the bulk of it: QuickDraw, Event Manager, Memory Manager, Window Manager, etc. Just ate it like an elephant. I don't think his regions were as clever as the Mac. Pretty sure he just stuck with rectangles.

I'd like to see something like Carbon for old apps so that they boot in modern window frames (without the missing Tahoe corners) and can save to files.

I can't imagine how fast this is compared to the original hardware that ran it. I remember using a Mac 512k with a single floppy drive (no hard drive support) and doing the insert-floppy-dance. Computers were far more mechanical then.

It would be fun to have a "slow it down" feature that also has the various floppy read/write noises paired with it. Bonus points for different generations of hardware and having the OG HD noises to pair with those too!