Alternate ROM Register

Number	TBRegisterNumber::$8C
Readable	TBRegisterReadable::Yes
Writable	TBRegisterWritable::Yes
Short Description	ShortDesc::Enable alternate ROM or lock 48k ROM

Bit	Description
	Values affecting machine immediately
7	1 to enable alternate ROM
6	1 to make alternate ROM visible only during writes, 0 to make alternate ROM visible during reads
4	1 to lock 48k ROM
	After soft reset (will be copied to bits 7-4)
3	1 to enable alternate ROM
2	1 to make alternate ROM visible only during writes, 0 to make alternate ROM visible during reads
0	1 to lock 48k ROM

(new register since core 3.0.5)

(note: Next registers with number higher than $7F are inaccessible from Copper code)