RSR and the author are not affiliated with any company mentioned in this document. We’ll see them in action shortly. DMA transfers can also copy from a PPU register to CPU address space. I’d also encourage you to experiment a bit. I mention this because at times people get thrown off by PEA.

Then, in the subroutine (line 125) we first save the old stack pointer with PHX on the stack. DMA transfers can also copy from a PPU register to CPU address space. We’ll use this now to improve LoadVRAM. DMA by itself is pretty useful, but Nintendo thought up another way of using the DMA controller that really made the SNES the great console that it is.

Well, its fast. Lines 213 and 214 are the “standard case”: If there was neither a collision with the left or right screen boundary, we simply store the new horizontal position in the OAMRAM mirror and branch to the vertical collision check. HDMA uses the same channel registers as normal DMA, but has its own activation register ($420C). The HDMA Table has any number of "cells".

Lines 160 through 163: We initialize the (initial) horizontal and vertical speed of the sprites. Lines 57 and 64 might look a bit odd.

We know that each sprite needs four bytes of data in OAMRAM, so the offset for accessing the data of the other sprites is four. Most computer systems have some form of Direct Memory Access controller, which is basically a piece of hardware that allows I/O devices to copy to and from main memory independently of CPU control. The fact that the address space of the SNES is much bigger than the actual number of addresses isn't a problem.
For example, the two loops VRAMLoop and CGRAMLoop starting at line 42 and 58 respectively are almost identical. First, in lines 192 and 193 we check whether the current speed is positive/to the right, then we skip the check on the check for the left screen boundary (the sprite can’t hit the left screen boundary while it is moving right). First, we use DMAP0 to configure DMA channel 0. Unfortunately this unit's APU come as soldered chips in the mobo (not socketed nor removable).

The indirect mode is enabled by a bit in $43x0 as well. To reiterate what dogp observed: A lot of games explicitly wait forever for the APU to get ready before they'll boot, so if you have a socketed APU, you could try re-seating it. In essence, it needs three bits (no pun intended) of information: We’ll pass the arguments by stack. We haven’t talked about this in detail, but many of the memory mapped registers can only be used during V-blanking; i.e., you can’t update graphics (VRAM, OAMRAM, etc.) On a 64-bit machine, pointers are large enough to address 1.844674407×10 19 bytes, which is about 10 billion GB. I do assembly programming on old machines and boat building. by lidnariq » Wed Aug 24, 2016 1:34 pm, Post Since we can access WRAM directly without going through memory mapped registers first, it is easier for us to update the position, color, etc.

I guess this makes things worse since It seems that my unit's failure rest either in the S-CPU or the S-WRAM... SNES Repair Attempts - How'd you go for troubleshooting? Lines 164 through 194: This shouldn’t surprise you either, it’s pretty much the same as in the LoadVRAM subroutine. Please keep in mind that this main game loop is not optimized; there’s a lot of code repetition and redundancies. Next, let’s look at the subroutine itself. If you’re unsure why and how this works, freshen up your knowledge on two-complements binary number arithmetics. If we want to move data from one memory segment to another, we need to know (or let the SNES know, to be precise) three things: There are a total of seven DMA channels on the SNES. Heisei Inu Monogatari Bow: Pop'n Smash!! Note that the DMA and HDMA channels use the same configuration registers (as outlined below), ie so if 4 HDMA are active then only 4 DMA can be done, etc.