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Communication port information

BrokenLizard - Nov 22, 2009

		Douglie007	Sep 29, 2020
		I have like 2 Memory cards full I would love to backup. The link I found for the fakefloppy doesnt work... does any one know a backup link? or is anyone selling them?

		slinga	Sep 30, 2020
		Fake floppy? Are you referring to the Sega Saturn Floppy Drive? According to this link: Secrets of the Floppy Disk Drive... the Sega Saturn Floppy Drive is not formatted to be read in PCs. You mentioned a Satiator is out of the option due to cost. What about using my Sega Saturn Extractor? slinga-homebrew/Save-Game-Extractor.... It is able to dump from carts.

		rorirub	Sep 30, 2020
		You could buy a rom programmer with the appropriate TSOP adapters and desolder the flash rom on the carts for dumping, but if a Satiator is out of your budget then I'd guess this would be too.

		Douglie007	Oct 1, 2020
		I was reading the beginning of this thread and the "fake Floppy" was something that looked like someone developed to replace the expensive reaI floppy drive. I tried to find the MiniModem but I could figure out how it worked with windows. Also once I have it on the PC I assume with the Save Extractor it cant get back. @slinga... Is there a way to get make the program so I could use the link cable and run the save copier on both Saturns to move saves between cards?

		slinga	Oct 1, 2020
		Here's what I would do: 1) Backup all saves from Saturn->PC with Save Game Extractor. Verify the MD5 hashes are correct. 2) Burn all saves to disk and copy from PC->Saturn with Save Game Copier. SGC can copy saves from CD to the backup cart. Another user got minimodem to work on Windows. I would recommend just setting up a Linux VM.

mrkotfw

Feb 25, 2021

	zone66x said:

How much did all of this cost?

This would be good to have for people who don't have access to a USB dev cart.

		Waterfuell	Apr 10, 2021
		Since some time ago I wanted to do something similar to zone66x, so based in his job Ive done my own serial saturn to usb cable. If anyone interested I can upload pcb designs, also got some spare pcbs and components. At the moment I use cable for uploading code to saturn, I needed it because I don have dev cart and I was limited to AR comms link. Edit: I was cleaning the car in my garage, and forget to upload one pic.

		_NetNomad	Apr 19, 2021
		This is awesome! I am definitely interested in those PCB designs if you're still willing to share them

		BrokenLizard	Apr 11, 2023
		My website is finally back up and you can now access Sega Saturn Floppy Disk Drive Communication Protoc... Version 1.4 again. I'm hoping to be able to revive my old projects, but I can't make any promises.

		BrokenLizard	Jun 7, 2023
		Server died again, but still working on the FDD.

		Knight0fDragon	Jun 8, 2023
		I would recommend talking with @slinga..., he disassembled the bios and has a lot of information about the communication from it.

		BrokenLizard	Jun 8, 2023
		I've had a working implementation for a very long time. Right now, I'm just porting the implementation to a new microcontroller, increasing transfer speeds, designing the enclosure, and designing an affordable cable.

Knight0fDragon

Jun 8, 2023

	BrokenLizard said:

I believe there were things that you may have gotten wrong. Like you have CRC as 4 bytes, but it is only 2 bytes as CRC-16

		BrokenLizard	Jun 8, 2023
		If rude messages like this persist, I will be forced to leave this site.

Knight0fDragon

Jun 8, 2023

	BrokenLizard said:

LOL ok buddy

		BrokenLizard	Jun 9, 2023
		The protocol document says it is CRC-16 CCITT (0xFFFF).

		slinga	Jun 9, 2023
		@BrokenLizard...: I appreciate your document. I spent a little bit of time comparing it to my own reverse engineering efforts: Decompilation of Backup Library.... In terms of the CRC length, I believe at some point your document listed it as 4 bytes. If I am mistaken, I apologize. As you mentioned your link is down. My end goal is to include serial cable support to libslinga (GitHub - slinga-homebrew/libslinga: Sega Saturn sa...). Everything included in libslinga will be supported by Save Game Copier (GitHub - slinga-homebrew/Save-Game-Copier: Copy Se...). As libslinga is MIT licensed it is freely available for anyone to use. What is your goal, to sell serial cables? Allow for users to backup their saves to PC? Make a cable for yourself? As @Knight0fDragon... suggested, there is room for us to collaborate. Test your cables with libslinga\Save Game Copier etc.

BrokenLizard

Jun 9, 2023

I'm planning on getting my server back up this weekend (Newegg sold me a DOA HDD and then took two weeks to tell me the model is now out of stock).

The document describes the CRC as CRC-16 CCITT (0xFFFF) but in the individual command descriptions, the "crc" field is listed as occupying four bytes with the first two bytes being 0x0000 since those two bytes were always 0 in my testing. I could have just as easily marked those two bytes as pad bytes. During the reverse engineering portion of my project, I solely looked at captured communications port traffic and didn't look as any machine code (or source code). As a result, there is a chance that some fields described by my protocol document do not list potentially valid values or conditions, simply because I was never able to observe them.

Checksum
A CRC16 CCITT (0xFFFF) checksum is used throughout the protocol. The checksum is always transferred as a 32-bit value, with the upper 16-bits set to 0x0000. The upper two bytes are used in the calculation of the checksum.

My end goal, besides just enjoying working on the project, is to reproduce the floppy drive and either sell kits or fully assembled devices (assuming someone would actually be interested in paying for one).

For now, I'll attach the latest version of the document to this message. Also, I'm all for collaborating and I think we are working on different enough projects that neither will encroach on the other.