Re: AltairZ80 simulator updated

Try MS-DOS 1.25. You'll find more evidence that the 640k barrier is
not a limitation of MS-DOS, but rather a limitation of the PC
hardware. Of course, the IBM had to put memory-mapped I/O somewhere,
and 10x CP/M-80 RAM probably seemed reasonable at the time.

The 640 barrier was largely illusory anyway. Basic memory management
support in DOS had most of what it needed to support 1 MB, as evidenced
by the high memory support of later years.

The real mind blower is the short-sightedness of a 1 MB limit. The cause
of that one is the size of a paragraph, the basic unit of the segment
register.

De
.

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