T1200 fix: Memory test failure

[JohnElliott]

I found only one small issue after applying the patch.
The TEST1 utility fails (abort) when checking the memory, however the memory amount in 1MB/2MB config is correctly detected.

I've finally got round to looking at this. I think TEST1 is trying to test 2k of RAM at F000:0000, which I believe is an area of nonvolatile RAM used to suspend the computer. What I'm not sure of is whether it's supposed to be mapped all the time or paged in/out on command.

I've attached a patch which may help, though on my build (with or without the patch) TEST1 fails during the ROM test and doesn't get as far as testing RAM. However I was able to test with a different utility, TESTCE1, which gave a failure on 'Backup RAM' without the patch and succeeded with it.

[SarahWalker]

Committed at rev 1116.