Address Bus A

Address Bus A is the SNES' 24-bit bus. It is drawn in orange in the colorized jwdonal schematic, and its individual address lines are labeled CA0-CA23.

It is connected to:

• S-CPU pins 2-17 and 93-100
• WRAM pins 23-31 and pins 34-42
• Cartridge Slot pins 6-17 and 37-48

It is 24 bits wide because that is how big the 5A22's address space is:

• The high 8 bits are the bank byte
• The middle 8 bits are the page number
• The low 8 bits are the byte number

It can address up to 16 megabytes, which is enough for most games, but some games use cartridge bank switching to address even more.

See Also

• Address Bus B
• CPU Data Bus

Reference

1. Figure 2-22-1, "Super NES Functional Block Diagram" on page 2-22-2 of Book I