[MiNT] Test for ST-ESCC fails on TT

[Mario Becroft <mb@tos.pl.net>]

I have now been able to compile the MiNT kernel, and so the first thing I
looked into is how, on the TT, MiNT detects an "ST-ESCC" even though it is
not present.

I do not know exactly what impact this has on the operation of MiNT but
presumably some serial port functions don't work properly. I hope this has
something to do with why MiNT never detects the a dropped carrier, and
will not negate DTR properly on a serial port. I will disable this test
later and see if it helps with any of these problems.

Anyway the problem is that on the TT the memory locations read as a test
for the presence of the ST-ESCC hardware do not generate a bus error, and
so the test thinks an ST-ESCC is present. On the TT these locations seem
to read all 1's. Perhaps the test can be improved along those lines, if
the ST-ESCC never really reads all 1's. If the ST-ESCC registers do,
however, sometimes read as all 1's then a different approach would be
needed.

-- 
+-----------------------------------------------------------------------+
| Mario Becroft                * Tariland, New Zealand Atari User Group |
| mb@tos.pl.net                * Atari Hardware Developments            |
| http://www.ak.planet.gen.nz/~mario/ * Atari Serial Mouse Interface    |
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