address |
register |
check |
$bfe001 |
ciaa.ciapra |
setting the Overlay bit #0 is prohibited |
$bfe201 |
ciaa.ciaddra |
bits #6-7 can have any value (used for joypad), lower bits must be
%000011 |
$bfe801 |
ciaa.ciatodlow |
read-modify-write accesses (e.g. bchg) are not allowed
if ALARM bit is set in ciaa.ciacrb (only checked on 68060) |
$bfe901 |
ciaa.ciatodmid |
$bfea01 |
ciaa.ciatodhi |
$bfed01 |
ciaa.ciaicr |
read-modify-write accesses (e.g. bchg) are not allowed (only
checked on 68060) |
$bfd100 |
ciab.ciaprb |
the bits for MOTOR #7, SELECT #3-6 and STEP #0 must not be
cleared, other bits can be changed; with that any accesses to the
floppy drives will be detected |
$bfd200 |
ciab.ciaddra |
the value written must be %11000000 |
$bfd300 |
ciab.ciaddrb |
the value written must be %11111111 |
$bfd800 |
ciab.ciatodlow |
read-modify-write accesses (e.g. bchg) are not allowed
if ALARM bit is set in ciab.ciacrb (only checked on 68060) |
$bfd900 |
ciab.ciatodmid |
$bfda00 |
ciab.ciatodhi |
$bfdd00 |
ciab.ciaicr |
read-modify-write accesses (e.g. bchg) are not allowed (only
checked on 68060) |