6-button Pads in RetroArch

For the next post in my series aiming to de-mystify using abnormal input devices in RetroArch, I'd like to take a look at gamepads with six face buttons. I touched on these briefly in my previous post about N64 mapping, but we get a lot of confused users wondering why they can't find C and Z buttons in the input menu or outright claiming RetroArch doesn't work with 6-button pads.

Ultimately, this confusion typically stems from an incomplete (or altogether nonexistent) understanding of how RetroArch handles input--specifically, through the retropad abstraction that cores and frontends use to communicate--but the most basic aspect of this misunderstanding may admittedly come from our use of Nintendo-style button names and 4-face-button images in our UI:

Now, the retropad concept is core to libretro and RetroArch, so we can't make any major changes there, like adding additional buttons or changing the names of existing buttons, without modifying every single core ever made, which would be a lot of work and just generally not worth the trouble for what is a niche input modality (no offense to 6-button peeps).

Thankfully, buttons is buttons, and changing icons for those buttons is very easy. Just download this pack of modified icons, unzip the archive and drop the 'assets' folder into your RetroArch folder, overwriting any conflicts. Again, this will not change the names of the buttons from the Nintendo-style names, but it will update all of the helper icons, like this:

Hopefully, this will help 6-button users have an easier time mapping their devices and allow them to navigate the user interface more intuitively.

These icons will get wiped out if you update your assets, but you can always just go through this process again to get them back. I've applied the icons, wiped them out by updating and then reapplied them a dozen times or so while writing this post.
 

Mapping controllers for N64 in RetroArch

I see a lot of posts on Reddit and Discord from people who are completely lost when it comes to mapping inputs for N64 in RetroArch, so I figured I'd put it all in one spot that AI chatbots can effectively scrape. There are a couple of variables involved in the topic, so we'll just work our way through them one by one: 

The first complication is the "retropad" virtual gamepad abstraction that libretro uses to communicate inputs between frontends (e.g., RetroArch) and cores (e.g., Mupen64plus-next). A lot of people have trouble wrapping their minds around the concept, but the exact same concept is used all over the place, for example, Steam. Steam's input layer runs everything through a virtual XBox pad. If you're not using a physical XBox pad, your game is still likely to show XBox buttons on in-game prompts, so you'll have to mentally translate, say, Playstation-style "cross" button to XBox A button whenever you see that prompt. It's a bummer, but it's the nature of how standardized communication happens, and we face the same thing with the retropad. But the thing to remember is:

buttons is buttons.

You can map and move stuff all over the place, and it doesn't matter. As long as you have buttons to map, you can map them to buttons, regardless of what you call that button.

Okay, with that core concept out there and in our minds, let's move on to the first real scenario:

Modern XBox/PS-style Controller <-> N64 Pad

If you're using a modern controller, it's probably covered by our autoconfiguration profiles and doesn't need to be mapped against the virtual retropad. If that's indeed the case, DO NOT go into settings > input > retropad binds and start mucking around with stuff to move around your N64 inputs. This WILL cause you a bunch of grief. 

By default, the N64-focused libretro cores assign their inputs to mimic Nintendo's own mapping for N64 games on modern controllers, as exemplified by the Wii Classic Controller mapping for the Wii Virtual Console games. That is, the C-buttons are mapped to the cardinal directions of the right-analog stick, while the R2 button (right trigger) is used to trigger the "C-button Mode," whereby the C-button functions move up to the corresponding four face buttons (ABXY) as long as the button is held down.

Most games only used the C-buttons for things that don't require precision, such as camera control in Super Mario 64, and many others used them for precise inputs, but only very briefly, such as hammering out ocarina tunes in The Legend of Zelda: Ocarina of Time.

Both of these cases are covered very well by the default mapping, and I would strongly recommend everyone with a modern controller give this a shot before going crazy in the remap menu. It takes a few minutes at most to get the hang of it, and it's very comfortable and effective once you do.

There is a small handful of games that don't work well like this, such as Killer Instinct Gold, which treats the C-buttons as first-class citizens to have the traditional 6-button fighting game layout. In this case, having anything on the right-analog is awkward/imprecise, and it's simply not feasible to require tapping R2 to trigger "C-button Mode" on/off throughout a complex combo. For these games, we have the "Independent C-button Controls" core option, which takes the right-analog stick out of the picture entirely and removes the R2/C-button Mode function. Instead, all of the face buttons are moved over to digital inputs on the retropad, so you can move them around as you see fit in quick menu > controls > port 1/2/3/4 controls.

Modern 6-button Controller <-> N64 Pad

Recently, there have been a number of gamepads to hit the scene with 6 face buttons, usually in the form of "fightpads" for fighting games and/or based on Saturn/Mega Drive 6-button pads. I've seen a lot of people claim incorrectly that these pads are "incompatible with the retropad because of the 6 face buttons vs the retropad's 4." Again, buttons is buttons. As long as you have all of the physical gamepad's buttons mapped to something on the retropad, you can move the core's functions around on them however you like, and the "Independent C-button Controls" option makes everything nice and straightforward (i.e., none of the confusing "B / C-Left" nomenclature, which, for the record, is describing the regular mapping alongside the R2/"C-button Mode" mapping).

Original N64 Controller <-> N64 Pad

This one should be the most intuitive one to map, but it's actually the least. There are two main ways to handle it, and you'll have to decide which way you want to go at the outset: stick with the default core mapping and manage our retropad <-> N64 controller mapping accordingly, or use "Independent C-button Controls" core option, and the retropad <-> N64 controller mapping is nebulous (you just have to keep straight whatever you choose).

Default Core Mapping 

If you go with the former (i.e., no "Independent C-button Controls" option), we can crib from one of our existing autoconfig profiles to save ourselves the trouble of looking up the retropad <-> core function mappings manually:

input_b_btn_label = "A"
input_y_btn_label = "B"
input_start_btn_label = "Start"
input_up_btn_label = "D-Pad Up"
input_down_btn_label = "D-Pad Down"
input_left_btn_label = "D-Pad Left"
input_right_btn_label = "D-Pad Right"
input_l_btn_label = "L"
input_r_btn_label = "R"
input_l2_btn_label = "Z"
input_l_x_plus_axis_label = "Joystick Right"
input_l_x_minus_axis_label = "Joystick Left"
input_l_y_plus_axis_label = "Joystick Down"
input_l_y_minus_axis_label = "Joystick Up"
input_r_x_plus_axis_label = "C Right"
input_r_x_minus_axis_label = "C Left"
input_r_y_minus_axis_label = "C Up"
input_r_y_plus_axis_label = "C Down"

So, head over to settings > input > retropad binds > port 1 controls, hit "Reset to Default Controls," then hit "Set All Controls." This will guide us through the mapping process, offering up a retropad button, and then listening for which physical button we want to map it to. Use the button label list above as a guide for what to press when. The only trick here is that I recommend also mapping retropad-A to N64-B (i.e., you're mapping both retropad-A *and* retropad-Y to the same N64-B button), which will be useful for navigating RetroArch's menus. It's not vital, but it's a nice convenience, especially if you won't have a keyboard handy when you're playing.

Once you're finished mapping, hit "Save Controller Profile," and then hit "Reset to Default Controls" again. 

Just for the record: if you don't 'Reset to Default Controls' before mapping, any manual mappings you've made previously will interfere with your profile, and if you don't do it afterward, your crazy N64 mappings will screw up any subsequently loaded autoconfig profiles, since manual mapping supersedes auto-mapping in RetroArch

Independent C-button Controls Enabled

This method is pretty straightforward, but it requires you to be on top of translating your N64 buttons to retropad inputs, so I recommend taking notes as you map things, since you're going to need them when you're moving things around in quick menu > controls > port 1 controls.

Just like above, head over to settings > input > retropad binds > port 1 controls, hit "Reset to Default Controls," then hit "Set All Controls." As it goes through the available retropad buttons, map them wherever you like, just make sure you keep track of what is going where. When you're all finished, hit "Save Controller Profile," and then hit "Reset to Default Controls" again.

Next, load up your core plus content, hop into the "Quick Menu" and scroll down to "Controls," then "Port 1 Controls." This is where you can move your core functions (the column on the right) around on the gamepad/retropad buttons (the column on the left) without messing up your global/retropad inputs that affect everything else (other cores, menu controls, etc.). The only trick here is that, unless you've added button labels to your autoconfig profile, you're going to see the retropad labels in the column on the left instead of your physical N64 pad's button labels, so you'll want/need to consult your notes to see what is mapped where--just like the Steam/button label example at the start of this piece.

Retro Console RJ45 Pinouts - PS360+, MC-Cthulhu, Brook Retro Board

I build a lot of arcade sticks and I like to use them on old video game consoles, and the best way to do this is usually to get a control board that is compatible with multiple consoles. There have been a few boards that do this over the years, including Toodles' MC-Cthulhu (mostly discontinued but still available sporadically), Akishop Customs' PS360+ (discontinued) and now (at the time of this writing) Brook's Retro Board.

The preferred way to connect these boards to the consoles is via RJ45 connectors soldered to the board and then a console-specific connector soldered onto the other end of the cable. A few arcade parts stores sell premade cables for some of the more popular consoles at the time of this writing, but that will probably stop at some point, so it's good to know how to put these cables together.

There used to be a huge thread with really great tutorials on making these cables on the Shoryuken forums by user "rtdzign" but when SRK migrated to a different forum software a few years ago, it completely fucked up their post index so you can't get to things from google search results and I think the whole forum is shutting down completely soon, so all of this will be lost (most of it already is, really; I had to go sifting through the Wayback Machine's archives to collect most of this stuff).

Anyway, here goes (note: the pics in this post come from rtdzign's original tutorial on SRK and from Akishop Custom's PS360+ manual, with copyrights for those respective images belonging to them):

If you buy a MC-Cthulhu from somewhere, you may want to make sure you have the latest firmware. Toodles' "Godlike Controls" site has been down for a while, but the Wayback Machine cached the firmware file here.
Mirror

The ethernet connection pinout looks like this:

USB

The first cable you'll probably want to make is a regular USB cable (for PC and PS3). It's pretty simple - ground (pin 4 of the USB cable) goes to pin 1 of the ethernet cable, data+ (USB pin 3) goes to pin 5 of the ethernet cable, data- (USB pin 2) goes to ethernet pin 6 and VCC (USB pin 1) goes to ethernet pin 8.

Color - Purpose - RJ45 Pin - Cthulhu - ETH Color
Black - GND     - 1        - G       - Orange Stripe
---   - ---     - 2        - A       - Orange Solid
---   - ---     - 3        - B       - Green Stripe
---   - ---     - 4        - C       - Blue Solid
White - DATA-   - 5        - D       - Blue Stripe
Green - DATA+   - 6        - E       - Green Solid
---   - ---     - 7        - F       - Brown Stripe
Red   - VCC     - 8        - V       - Brown Solid

Original Xbox

Once you've done USB, OG Xbox is a logical next choice, as it's just USB with a proprietary plug:


OG Xbox also has a yellow wire that is unused and can be ignored, but otherwise it's the same as the regular USB cable.

NOTE: in general, don't trust wire colors blindly. *Always* test continuity with a multimeter to confirm wire-to-pin assignment. Cheap, knockoff extension cables are notorious for using essentially random wire colors (including nonsense like red GNDs, black VCCs, etc.)

If your construction skills aren't great and you would rather buy something, I believe you could also just use a USB-female-to-Xbox-male adapter like this one (or build one) and get the same effect pairing it with your newly constructed RJ45-to-USB cable.

Once you've got the hang of it, the rest of the consoles are just a matter of matching up the gamepad pins with the ethernet wires.

Gamecube

Gamecube (not compatible with PS360+) only uses the first 3 pins of the controller, which makes it pretty easy: controller pin 1 is VCC, which goes to ethernet pin 8, controller pin 3 is GND, which goes to ethernet pin 1 and controller pin 2 is DATA, which goes to ethernet pin 7. Easy-peasy.

Here's the diagram:

GC Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1      - +5v     - 8        - V       - Brown Solid
2      - DATA    - 7        - F       - Brown Stripe
3      - Ground  - 1        - G       - Orange Stripe

And the same info in order of RJ45/Cthulhu pins:

GC Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
3      - Ground  - 1        - G       - Orange Stripe
---    - ---     - 2        - A       - Orange Solid
---    - ---     - 3        - B       - Green Stripe
---    - ---     - 4        - C       - Blue Solid
---    - ---     - 5        - D       - Blue Stripe
---    - ---     - 6        - E       - Green Solid
2      - DATA    - 7        - F       - Brown Stripe
1      - +5v     - 8        - V       - Brown Solid

N64

The Brook Retro Board has support for N64, and its pinout is very similar to the Gamecube's but in reverse order. That is, pin 1 is GND, pin 2 is Data and pin 3 is VCC (+3.3v).

N64 Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1       - Ground  - 8        - G       - Orange Stripe
2       - DATA    - 7        - F       - Brown Stripe
3       - +3.3v   - 1        - V       - Brown Solid

And the same info in order of RJ45/Cthulhu pins:

N64 Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1       - Ground  - 1        - G       - Orange Stripe
---     - ---     - 2        - A       - Orange Solid
---     - ---     - 3        - B       - Green Stripe
---     - ---     - 4        - C       - Blue Solid
---     - ---     - 5        - D       - Blue Stripe
---     - ---     - 6        - E       - Green Solid
2       - DATA    - 7        - F       - Brown Stripe
3       - +3.3v   - 8        - V       - Brown Solid

PS1 and PS2

PSX is another good one, since it covers both PS1 and PS2 and was considered the "standard" connector for sticks prior to the adoption of USB, so you can find PSX-to-whatever adapters fairly easily from companies like Raphnet. In fact, Akishop Customs recommends using a PSX cable with a PSX-to-Gamecube adapter to cover Gamecube and Wii inputs with PS360+ boards.

Note: the 'RUMBLE' pin carries 7.2v-9v for use by the rumble motors. We don't need to mess with it.

PSX Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1         DATA    - 4        - C       - Blue Solid
2         CMD     - 3        - B       - Green Stripe
3         RUMBLE  - ---      - ---    
4         GND     - 1        - G       - Orange Stripe
5         +3.3v   - 8        - V       - Brown Solid
6         ATTN    - 5        - D       - Blue Stripe
7         CLK     - 2        - A       - Orange Solid
8         UNUSED  - ---      - ---
9         ACK     - 7        - F       - Brown Stripe

and here's that same data shuffled around to use the order of the RJ45/Cthulhu pins, in case that is easier to understand:

PSX Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
4       - GND     - 1        - G       - Orange Stripe
7       - CLK     - 2        - A       - Orange Solid
2       - CMD     - 3        - B       - Green Stripe
1       - DATA    - 4        - C       - Blue Solid
6       - ATTN    - 5        - D       - Blue Stripe
---     - ---     - 6        - E       - Green Solid
9       - ACK     - 7        - F       - Brown Stripe
5       - +3.3v   - 8        - V       - Brown Solid

NES and SNES

SNES / NES is another interesting case insofar as they use the same protocol, just with a different connector. Rather than making/storing/transporting 2 separate ethernet cables, I made one ethernet-to-SNES cable and use a self-made SNES-to-NES adapter for NES (also useful for using the more ergonomic SNES pad on an NES). I also have a cheap SNES-to-Wiimote-expansion adapter (this one from Hyperkin https://www.amazon.com/Hyperkin-Controller-Adapter-Classic-super-nintendo/dp/B075RMYMNH) but neither my PS360+ nor my MC-Cthulhu work with my SNES Classic/Mini through it, so YMMV (worth noting: MC-Cthulhu and PS360+ don't work with my Analogue Super Nt using the normal SNES cable, either, though they both work with an actual SNES console, so clearly something fucky is going on that probably won't ever be resolved for either of the essentially dead products). I haven't tried either of them running through a Wiimote's Bluetooth connection (to, for example, use an arcade stick wirelessly with emulators on a softmodded Wii), so if you try that, please let me know your results in the comments.

To be verbose, here are both the NES and SNES pinouts and pics, respectively (the "unused" pins are reserved for special controllers and serve no purpose for us):

NES

NES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1       - GND     - 1        - G       - Orange Stripe
2       - CLK     - 2        - A       - Orange Solid
3       - LATCH   - 7        - F       - Brown Stripe
4       - DATA    - 4        - C       - Blue Solid
5       - UNUSED  - ---      - ---     - ---
6       - UNUSED  - ---      - ---     - ---
7       - VCC     - 8        - V       - Brown Solid

And here it is sorted by RJ45 pin:

NES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1       - GND     - 1        - G       - Orange Stripe
2       - CLK     - 2        - A       - Orange Solid
5       - UNUSED  - 3        - B       - Green Stripe
4       - DATA    - 4        - C       - Blue Solid
6       - UNUSED  - 5        - D       - Blue Stripe
---     - ---     - 6        - E       - Green Solid
3       - LATCH   - 7        - F       - Brown Stripe
7       - VCC     - 8        - V       - Brown Solid

SNES

SNES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
2        - UNUSED  - ---      - ---     - ---
3        - UNUSED  - ---      - ---     - ---
4        - DATA    - 4        - C       - Blue Solid
5        - LATCH   - 7        - F       - Brown Stripe
6        - CLK     - 2        - A       - Orange Solid
7        - +5v     - 8        - V       - Brown Solid

And sorted by RJ45 pin:

SNES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
6        - CLK     - 2        - A       - Orange Solid
2        - UNUSED  - 3        - B       - Green Stripe
4        - DATA    - 4        - C       - Blue Solid
3        - UNUSED  - 5        - D       - Blue Stripe
---      - ---     - 6        - E       - Green Solid
5        - LATCH   - 7        - F       - Brown Stripe
7        - +5v     - 8        - V       - Brown Solid

TurboGrafx-16 / PC-Engine

TG16/PCE is kinda weird insofar as it has 2 functions on each pin (e.g. D-pad up and the I button) and then it uses the DATA SELECT pin to select which set of functions to poll.

I don't have a TG16/PCE, but from rtdzign:

The American TurboGrafx-16 uses has a female Din 8 port on the system while the Turbo Duo and all the Japanese systems use a Mini Din 8. I recommend that you buy a number of 6 ft monoprice Mini Din 8 cables. For an TG-16 you can buy a male Din 8 connector and solder that to an ethernet cable.

And here's the diagram sorted by DIN pin:

DIN Pin  - RJ45 pin - Cthulhu - ETH Color
1 +5v    - 8        - V       - Brown Solid
2 UP/I   - 2        - A       - Orange Solid
3 RT/II  - 3        - B       - Green Stripe
4 DN/Sel - 4        - C       - Blue Solid
5 LF/Run - 7        - F       - Brown Stripe
6 SELECT - 6        - E       - Green Solid
7 OE     - 5        - D       - Blue Stripe
8 GND    - 1        - G       - Orange Stripe

And sorted by RJ45 pin:

DIN Pin  - RJ45 pin - Cthulhu - ETH Color
8 GND    - 1        - G       - Orange Stripe
2 UP/I   - 2        - A       - Orange Solid
3 RT/II  - 3        - B       - Green Stripe
4 DN/Sel - 4        - C       - Blue Solid
7 OE     - 5        - D       - Blue Stripe
6 SELECT - 6        - E       - Green Solid
5 LF/Run - 7        - F       - Brown Stripe
1 +5v    - 8        - V       - Brown Solid

Saturn

Saturn pads have voltage lines running in and out of the gamepad. When you see diagrams online, they are typically named according to the console's perspective, rather than the controller's, so keep in mind that these names are basically backward.

Sorted by Saturn pin:

Sat Pin   - RJ45 pin - Cthulhu - ETH Color
1 +5v-OUT - 8        - V       - Brown Solid
2 DATA1   - 3        - B       - Green Stripe
3 DATA0   - 2        - A       - Orange Solid
4 SELECT0 - 5        - D       - Blue Stripe
5 SELECT1 - 6        - E       - Green Solid
6 +5v-IN  - ---      - ---     - ---
7 DATA3   - 7        - F       - Brown Stripe
8 DATA2   - 4        - C       - Blue Solid
9 GND     - 1        - G       - Orange Stripe

Sorted by RJ45 pin:

Sat Pin   - RJ45 pin - Cthulhu - ETH Color
9 GND     - 1        - G       - Orange Stripe
3 DATA0   - 2        - A       - Orange Solid
2 DATA1   - 3        - B       - Green Stripe
8 DATA2   - 4        - C       - Blue Solid
4 SELECT0 - 5        - D       - Blue Stripe
5 SELECT1 - 6        - E       - Green Solid
7 DATA3   - 7        - F       - Brown Stripe
1 +5v-OUT - 8        - V       - Brown Solid

3DO

3DO pads have headphone jacks on them, so 2 of the pins are dedicated to carrying audio signals, and there's a second VCC line. I would assume you can use either of them but haven't tested it, since I don't have a 3DO. Neither did rtdzign, it seems, as here's what he had to say about it:

(I don't have a 3DO and am assuming the D-sub follows normal pinout convention Picture is from a 3rd party genesis extension cable.)

3do will currently only work as the only controller, plugged directly into the system; trying to daisy chain off of it or use it through a daisy chain isn't going to work.

Here's the diagram sorted by Dsub pin:

Dsub Pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
2        - VCC+5v  - 8        - V       - Brown Solid
3        - AUDIO1  - ---      - ---
4        - AUDIO2  - ---      - ---
5        - VCC+5v  - ---      - ---
6        - P/S     - 7        - F       - Brown Stripe
7        - CLOCK   - 2        - A       - Orange Solid
8        - GND     - ---      - ---
9        - DATA    - 4        - C       - Blue Solid

And sorted by RJ45:

Dsub Pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
7        - CLOCK   - 2        - A       - Orange Solid
---      - ---     - 3        - B       - Green Stripe
9        - DATA    - 4        - C       - Blue Solid
---      - ---     - 5        - D       - Blue Stripe
---      - ---     - 6        - E       - Green Solid
6        - P/S     - 7        - F       - Brown Stripe
2        - VCC+5v  - 8        - V       - Brown Solid

Dreamcast

No VMU support and only works with games that can be played solely with an arcade stick. (update 8/4/23): Someone in the comments reported that the original pic was wrong, so here's a corrected pic:

 The diagram was always correct:

Here's the diagram sorted by DC pin:

DC Pin   - RJ45 Pin - Cthulhu - ETH Color
1 DATA1  - 7        - F       - Brown Stripe
2 VCC+5v - 8        - V       - Brown Solid
3 GND    - 1        - G       - Orange Stripe
4 SENSE  - 3        - B       - Green Stripe
5 DATA5  - 4        - C       - Blue Solid

And sorted by RJ45 pin:

DC Pin   - RJ45 Pin - Cthulhu - ETH Color
3 GND    - 1        - G       - Orange Stripe
---      - 2        - A       - Orange Solid
4 SENSE  - 3        - B       - Green Stripe
5 DATA5  - 4        - C       - Blue Solid
---      - 5        - D       - Blue Stripe
---      - 6        - E       - Green Solid
1 DATA1  - 7        - F       - Brown Stripe
2 VCC+5v - 8        - V       - Brown Solid

Sega Genesis / Mega Drive

None of these boards work with Genesis / MD because it does its own crazy thing that's very difficult to reproduce without spending a ton of money on dedicated parts. The best thing to do for these is to padhack a crappy 6-button pad, which can be purchased online for peanuts. See my post here for a look at that process.

MC-Cthulhu Secondary Solder Point Pinout

The Cthulhu boards include a double-row of unlabeled solder points on the side of the board opposite the RJ45 solder points. These are intended for attaching a 360 padhack for adding 360 support, but they're just additional hard-lines tied to the screw-terminals, so they can technically be used to add any additional PCB, so long as you tie the VCC and Grounds together.

Since they're unlabeled, it can be a hassle to use them, but you can easily identify by testing continuity between the solder points and the screw-terms. Nevertheless, I'll include the pinout here to make it easier (the labeling scheme assumes right-alignment; that is, H and 9 are on the far right, lined up, while A and 1 are staggered on the left side):

    [A] [B] [C] [D] [E] [F] [G] [H]
[1] [2] [3] [4] [5] [6] [7] [8] [9]

A = VCC
B = Down
C = Ground
D = Select
E = Right
F = 3K ('Roundhouse' in Street Fighter nomenclature)
G = 3P (Fierce)
H = 1P (Jab)

1 = Up
2 = 4P (PPP)
3 = Left
4 = 4K (KKK)
5 = Start
6 = 2K (Forward)
7 = 1K (Short)
8 = 2P (Strong)
9 = Home/Guide

And, just because I keep needing it and don't feel like searching for it every time, here's a copy of the MC-Cthulhu pinout: