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HIMEM.SYS source

vladstamate

Experienced Member
Joined
Dec 2, 2012
Messages
197
Location
Orlando, FL, USA
I've read that Microsoft has release the source for HIMEM.SYS for early versions however Google search showed up nothing (except a link to microsoft.com download that does not work anymore).

Anyone has any idea where I can grab that from?

Regards,
Vlad.
 
There's a copy here. Is that what you're looking for?

EDIT: When reading HIMEM.ASM I immediately find this sticking out like a sore thumb;
Code:
	    cmp     bl,16		; Test for "legal" DOS functions
	    jle     short IOtherFunc
It's kind of sad that I can spot a bug in less than 30 seconds while the original Microsoft programmers apparently never did (I haven't checked but I bet it's still in there).

EDIT2: I just checked the version that comes with Windows 98 SE (version 3.95?) and it is actually fixed there.
 
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Reading the source, I was a little disappointed to see that copying blocks on a 386 is still just copying blocks, instead of remapping pages or something more elegant. Everyone seemed to hate EMS, but EMS -- both real and emulated -- remaps pages to the page frame, so it was a very quick operation.

HIMEM appears to go into "unreal" mode ("big real mode") to perform a copy.
 
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