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Error says Unable to control A20 line

Puffin1
Puffin1 asked
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Last Modified: 2010-04-27
I'm trying to upgrade an old 486 I got free. But when it boots it says "Error Unable to control A20 line. XMS driver not installed." So emm386 does not install either.

I've checked config.sys. The appropriate lines are there, lines 1 and 2, for himem.sys and emm386. The latter has noems and highscan. I've tried with and without noems and highscan.

The files are where they should be. I recopied them in case they were corrupt.

After getting the 486, I changed out the controller card, 3.5 floppy, and installed an old SoundBlaster card and new CD. All work in dos just fine, and pass diagnostics. The system is dos 6.22 and win 3.11.

The pc was formerly on a network, and I've tried to remove all network references, as it isn't on a network now and doesn't have a network card at present.

What can I do to get himem to load?
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I tried the first option, adding /A20control:off and even though it goes through the initial memory check okay, it now hangs in bootup at "HIMEM checking extended memory". So now I can't edit config.sys.

I checked to see if the memory modules (4 30 pin 1x9s) were seated okay. I had taken them out to see if I could use some other memory I had, but they didn't work, so I replaced them.


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