It was a quirk due to the number of address lines on the low end models, and it was a massive code smell, as 68020 and up could use 32 bit addresses so any code that did this would fail on machines with the faster CPUs.
Amiga Basic for example, wouldn't run on 68020 up because Microsoft used the upper 8 bits (amongst a whole slew of other horrible bugs and performance problems - it's probably the worst Microsoft product ever in terms of code quality)
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It was a quirk due to the number of address lines on the low end models, and it was a massive code smell, as 68020 and up could use 32 bit addresses so any code that did this would fail on machines with the faster CPUs.
Amiga Basic for example, wouldn't run on 68020 up because Microsoft used the upper 8 bits (amongst a whole slew of other horrible bugs and performance problems - it's probably the worst Microsoft product ever in terms of code quality)