Re: What do you get when you access RAM that isn't there?

[Andy McFadden <fadden@fadden.com>]

Dosius <steve@dosius.zzn.com> wrote:
>> If memory serves, it was a pattern of largely 00 and ff bytes, with
>> some semi-random other junk.  I can't remember if the results were
>> stable.
> 
> I wonder how DOS detected a sub-48K system then...

Write a byte.  Read it back.  Write a different byte.  Read it back.

Pick the bytes carefully (not $ff or $00).  $55/$AA might be a good combo.
So long as the results are semi-stable or semi-predictable, you should
pretty much always get the right answer.

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