Is there a detail on how TG-16 memory save works?

[7800fan]

Turbografx 16 can have save games via addon such as Turbobooster Plus and Turbo CD system. Also Backup Booster and Ten No Koe for PC Engine or Coregrafx. All are pin compatible with each other although connector shape is a bit different, the USA model has a trapezoid shaped connector and Japanese model has rectangle connector. A little filing will fix that

 

Anyway I can't find any info on how the backup part worked. I do know it involved an SRAM chip, a battery watchdog of some kind, a capacitor, and maybe another chip to handle communication with the host system.

 

My TG-16 has the CD system but the Turbo Express doesn't and can't interface at all. I was wondering if it was possible to hack in a memory save function.

[7800fan]

Started hitting Google with different search terms and I managed to dig up:

 

http://www.pcenginefx.com/forums/index.php?topic=16879.0

with these pictures: http://www.retrosampling.se/Temp/TNK2/1.png and http://www.retrosampling.se/Temp/TNK2/2.png and part list at http://www.retrosampling.se/Temp/TNK2/TenNoKoe2%20Components.txt

 

Also this one: https://www.assemblergames.com/forums/showthread.php?44903-Trying-to-reverse-engineer-Tennokoe-bank-2-picture-detail-and-need-help-IDing-parts

 

Common 2kx8 SRAM chip, could probably substitute the convoluted array of parts with a single battery watchdog or use NVRAM with compatible pinout and not worry about losing data for *years*

 

There is one problem: Hudson Soft HuC 6201 is a propriety chip with no detail on its gut. So that leaves 2 options: One hack and steal the chip from a Ten No Koe or other memory system. (I'd cry if someone ripped up a Turbo Booster Plus for the chip!) Two: prod some experts to reverse engineer it and make a FPGA or CPLD substitute (pretty sure a PAL won't cut it). I'm guessing its function is to monitor the bus at expansion port and connect with SRAM to pass data when requested.

[A Black Falcon]

The Tennokoe Bank is just a backup card, you can't save to it directly. It lets you copy memory banks from the system to the Tennokoe Bank. It also uses a battery instead of a capacitor, and probably has a different chip -- the internal memory save in CD or Duo units is 2KB, while the Tennokoe Bank is 8KB.

 

There's also the external Memory Base 128 unit, but only a handful of games can save directly to it; for other games you've got to use it like a Tennokoe Bank and transfer files back and forth, but you need a compatible game with an MB128 manager built in to do that, and all such games are CD titles, so it'd be useless on a TurboExpress/PC Engine GT, unfortunately... the MB128 is pretty cool though, it's 128KB and can hold 64 blocks! (It uses 4 AA batteries to store the data. Last maybe 7 months with good batteries. It's also got a large capacitor to hold the saves for a little while (like, an hour or something) while you change the batteries.)

 

I don't know if hacking a save chip into a TurboExpress is possible, but it'd be pretty interesting if it was...

 

Also refer to my TG16/CD/PCE save backup unit types and games supported list here (this thread inspired me to update the list a bit!): http://www.blackfalcongames.net/?p=190

 

Edit - ugh, finally got the link fixed.

Edited March 17, 2015 by A Black Falcon