Q: What happens to my “Golden Edition” Retrode?

A: The firmware will be [...]]]> This is a collection of questions regarding the Retrode2. Instead of responding to each and every comment individually (i.e., forum, YouTube, etc.), I’ll try to bundle the answers here. If your question is not answered, ask away in the comment section below the post.

Q: What happens to my “Golden Edition” Retrode?

A: The firmware will be maintained for both hardware versions jointly, and future plug-in adapters will remain downward compatible.

Q: Where, when, how much?

A: The Retrode2 is made in Germany (yay! no child labour except my very own) and will become available this summer, both directly from myself and via retail partners. As for the price tag, I can’t tell until all bills are paid. I’m aiming for EUR 65 (incl. VAT) for EU folks, or USD 85 (excl. VAT) worldwide.

Q: Will plug-in adapters be offered for sale?

A: They will be, but at a later time. Currently, I have no idea where to get LARGE quantities of cartridge shells to contain them. Gutting used games is not an option.

Q: Is the S2&K Mod integrated?

A: Yes.

Q: Why is the voltage switch hidden like this?

A: Because you don’t need it that often anyway. Also, cost.

Q: Will the SEGA slot fit 32X carts?

A: Not immediately since they are significantly thicker than regular carts. 32x carts do work when you insert the 32X adapter without power cable. I haven’t tried it, though, and the adapter may collide with the Retrode’s lid (which can be removed).

Q: Could the 9-pin ports be made to support other gamepads?

A: Depends, dedicated adapters may in fact be more versatile with that regard since the ports don’t need to share the bus with the cartridges. Atari VCS? Should work. Anything with analog knobs? Not without hardware mod. Odd controllers where the pins are used both directions? Not without hardware mod. ColecoVision? I don’t even find documentation on that one, so don’t know.

For the technically inclined, pins 1,2,3,4,6,9 are wired as digital inputs. Pin 7 is digital output (”Select”). Pin 5: +5V. Pin 8: GND. Anything that sticks to this scheme should run without problems.

Q: Is the recessed USB port wide enough for the cable connector?

A: In the prototype: no (well observed). In production: yes.

Q: NES plug-in? Really?

A: Wait a second. I’ve bought two NES cartridges but (1) they will have to wait until I find the time, and (2) there are more than two different types of memory mapping. Developing this plug-in will be a long and painful process, and there is simply NO WAY I’ll ever be coming near 100% or even 90% compatibility. According to this document, the two most popular memory mappers (MMC1/MMC3) should theoretically(!) give access to something like 1019 out of 1581 titles (64%) in the list — but frankly, I think the success rate will probably be more around 50%. Auto-detection of anything is near impossible, so a lot of settings will have to be made by hand.

Q: How is SA-1 support coming along?

A: No luck yet. Even using a SuperCIC, I did not manage to unlock the SA-1.

Q: How about a dedicated plug-in slot on the back side?

A: Due to the injection molding process, holes in any side walls are hard to achieve (the odd recessed shapes around the USB and LED are there for a reason). Also, I kind of like the plug-ins mechanically blocking the top slots, since it helps avoid conflicts between too many carts on the address/data buses.

Little file, big difference

[retrodeConfig] ; Remove first line for factory reset. ; Hex keycodes [...]]]>

Little file, big difference

[retrodeConfig]
; Remove first line for factory reset.
; Hex keycodes for (in this order) B Y SEL STA UP DN LFT RGT A X L R
; See usb.org/developers/devclass_docs/Hut1_11.pdf (pp.53ff)
[gamepad1] 06 1B 28 2C 52 51 50 4F 09 07 04 16
[gamepad2] 10 11 05 19 33 37 36 38 0E 0D 0A 0B
[filenameChksum] 1       ; checksum in filename?
[sramReadonly] 1         ; write protect SRAM by default
[segaRomExt] bin
[snesRomExt] sfc
[snesSramExt] srm


The file resides in the nonvolatile EEPROM and can be edited using any text editor. This is particularly neat for the gamepad keycode assignments, since saving the file will effectuate the changes immediately.

Implementing this (in particular, the parsing of the config file) may take a few hours, but this is actually so simple that I don’t see how it could possibly fail was actually more of a bitch than I thought it would be. Once I figured out that the C library comes with sscanf and the likes, things obviously got a lot easier :-D

EDIT: Added configurable file extensions.

Unfortunately, I could not get the suggestions from DiskDude’s otherwise ultra-helpful SNES Kart document to work, so I had to do a bit of my own reverse engineering. The main issue is getting the SRAM chip’s [...]]]> After quite some trouble trying to access the SRAM on the cartridge, I thought I would share the results here.

Unfortunately, I could not get the suggestions from DiskDude’s otherwise ultra-helpful SNES Kart document to work, so I had to do a bit of my own reverse engineering. The main issue is getting the SRAM chip’s !CS line to low state. This is accomplished by shredding a few control and address lines through a pair of 2-to-4 address decoders. Only when the combination of ones and zeros is right, the !CS input on the SRAM will go low. For Super Mario World (LoROM) and Super Mario Kart (HiROM), I reconstructed the following wirings: (click to magnify)

SRAM control for LoROM game (SMW)

SRAM control for HiROM game (SMK)

The correct values for accessing the SRAM appear to be as follows:

• HiROM: A13, A14, B5 high; A15, B6 low
• LoROM: RESET, B4, B5, B6 high; !CS low

As for reading and writing, any datasheet of a pin compatible SRAM chip, such as this one, should provide more than enough information.