Address Bus B: Difference between revisions

Latest revision as of 04:23, 15 January 2024

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

which is the exact same set of components that the CPU Data Bus is connected to. The SNES bus 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]

References

https://forums.nesdev.org/viewtopic.php?p=116505#p116505
Figure 2-22-1, "Super NES Functional Block Diagram" on page 2-22-2 of Book I
paragraph 3.2 on page 3-3-2 of Book I, lbid.

@@ Line 9: / Line 9: @@
 * 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.<sup>[1]</sup>
+which is the exact same set of components that the [[CPU Data Bus]] is connected to.  The SNES bus 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.<sup>[1]</sup>
+[[File:SNES Bus.png|thumb]]
 === See Also ===
 * [[Address Bus A]]
-=== Reference ===
+=== References ===
 # https://forums.nesdev.org/viewtopic.php?p=116505#p116505
+# Figure 2-22-1, "Super NES Functional Block Diagram" on [https://archive.org/details/SNESDevManual/book1/page/n98 page 2-22-2 of Book I]
+# paragraph 3.2 on [https://archive.org/details/SNESDevManual/book1/page/n160 page 3-3-2 of Book I], lbid.
 [[Category:SNES Hardware]]
 [[Category:Traces]]
 [[Category:Buses]]