- In the home computer world, each vendor had it’s own hardware/software stack.
- The standard language in the home computer world was BASIC.
Even in the CP/M world, you did not clone hardware, instead you license
CP/M from Digital Research and customized it for your own hardware.
- The IBM PC had BASIC in ROM, with support for cassette tapes.
- Or you could optionally purchase a floppy drive and run MS-DOS
- MS-DOS ended up being the dominant OS for the IBM PC because it was less expensive and available earlier.
- For several reasons, programs began doing direct hardware access and BIOS calls on the IBM PC.
- There were several MS-DOS computers that was only compatible at the DOS level, and they unfortunately failed due to the above.
- This forced more fully PC compatible clones.
- As a result of that need, Compaq and Phoenix
Technologies reverse engineered the IBM PC’s BIOS after people tried to
directly copy it, which was ruled as disallowed in the Apple vs
Franklin lawsuit. BTW, the BIOS cloners did not copy BASIC, which led
to the "No ROM BASIC" message.
- This resulted in IBM PC clones being the de facto standard.
before the IBM PC clones, there was the Apple II clones, one of which
led to the Apple vs Franklin lawsuit, but these did not become standard
like the IBM PC clones did, though the Apple II clones did clone BASIC
unlike the IBM PC clones.
- In the home computers, major
parts of the aforementioned software stack was often in ROM, to save
space as well as taking advantage of the results of the Apple vs
Franklin lawsuit. The Mac was no exception and in fact a major part of all versions of classic Mac OS is ROM patches.
- IBM and Apple
during it’s Mac clone days, as well as a few other vendors developed a
standard for PowerPC systems called CHRP that was intended to compete
with the IBM PC clones. As part of porting the Mac OS to support CHRP,
Apple moved the parts of Mac OS that was in ROM onto the disk.
- That kind of failed, but after Apple killed the Mac clones, CHRP was eventually developed into NewWorld used in the iMac and later.
Apple just after killing Mac clones in 1997, developed NewWorld which
makes it theoretically easier to create Mac clones (look at the Mac
emulators for example), but no one did.
- Then Apple moved to
Intel, which means that the current Intel Macs are internally almost no
different from those of a generic PC clone conforming to the
aforementioned de facto standard.
- Then people started hacking Intel Mac OS X to run on generic PC clones, and that led to Psystar.
BTW, what if the IBM PC compatible de facto standard did not exist? I
think that each home computer vendor would have it’s own
hardware/software stack, similar to the game consoles of today. And
extracting ROM images from computers for use on emulators would have