Memory Mapping Register

Number	TBRegisterNumber::$8E
Readable	TBRegisterReadable::Yes
Writable	TBRegisterWritable::Yes
Short Description	ShortDesc::Control classic Spectrum memory mapping

   bit 7 = port 0xdffd bit 0         \  RAM
   bits 6:4 = port 0x7ffd bits 2:0   /  bank 0-15
 R bit 3 = 1
 W bit 3 = 1 to change RAM bank, 0 = no change to mmu6 / mmu7 / RAM bank in ports 0x7ffd, 0xdffd
   bit 2 = port 0x1ffd bit 0            paging mode
 If bit 2 = paging mode = 0 (normal)
   bit 1 = port 0x1ffd bit 2         \  ROM
   bit 0 = port 0x7ffd bit 4         /  select
 If bit 2 = paging mode = 1 (special allRAM)
   bit 1 = port 0x1ffd bit 2         \  all
   bit 0 = port 0x1ffd bit 1         /  RAM

Writes can affect all ports 0x7ffd, 0xdffd, 0x1ffd

Writes always change the ROM / allRAM mapping

Writes immediately change the current mmu mapping as if by port write

(new register since core 3.1.1)

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