Address Bus B

Address Bus B, also known as the SNES bus, is 8-bits wide on the SNES Motherboard. Its individual address lines are labeled PA0-PA7, which stands for "peripheral address," as in S-CPU peripherals (not SNES peripherals). It is connected to:

• pins 51-58 of the S-CPU
• pins 5-12 of S-PPU1
• pins 17-24 of S-PPU2
• pins 48-51 of S-SMP
• pins 43-50 and 53-54 of WRAM
• pins 28-30 and 59-61, 3 and 34 of the Cartridge Slot
• pins 1-8 of the Expansion Port

It is drawn in purple in the colorized jwdonal schematic. Some people like to think of Address Bus B as being 16-bits wide, with the high byte being fixed to $21.^[1]

See Also

• Address Bus A
• CPU Data Bus

Reference

1. https://forums.nesdev.org/viewtopic.php?p=116505#p116505
2. Figure 2-22-1, "Super NES Functional Block Diagram" on page 2-22-2 of Book I