List of Registers with Unused Bits

The SNES has several registers which do not use all of their 8 bits. Some of them are:

Common Name	Unused Bits
INIDISP	4 - 6
OAMADDH	1 - 6
VMAINC	4 - 6
M7SEL	2 - 5
WOBJLOG	4 - 7
TM	5 - 7
TS	5 - 7
TMW	5 - 7
TSW	5 -7
CGSWSEL	2 - 3
SETINI	4 - 5
STAT77	4
STAT78	5
WMADDH	1 - 7
NMITIMEN	1 - 3 & 6
HTIMEH	1 - 7
VTIMEH	1 - 7
MEMSEL	1 - 7
RDNMI	4 - 6
TIMEUP	0 - 6
HVBJOY	1 - 5
STD CTRL 1L	0 - 3
STD CTRL 2L	0 - 3
STD CTRL 3L	0 - 3
STD CTRL 4L	0 - 3
PMON	0

Bits 10-12 of the Offset Change Mode data are unused. ^[1]

See Also

• Open Bus
• MDR
• The Infamous Bit-Of-Confusion

Reference

1. Appendix A-13 of Book I of the official Super Nintendo development manual