==ROM7 and ROMDIS in 6128 mode==
* ROMDIS does not prevent internal ROM7 to be selected, as on some regular 6128, unlike plus range.
* ROMDIS act as an output when ROM7 is selected (TBC : only on ROM7/0 ?)
* ROMDIS act as the DDI1 ROMDIS as it is active even during ram accesses.