SEGA-CD Memory Cart (US)

[hugh]

Does the SEGA-CD Memory Card use battery backup? As we are talking about battery back up. Does the SEGA-CD system 2 also have battery backup?

Hugh

[ASSEMbler]

I don't think it relies on battery. I think it's fram or something similar.

[hugh]

I don't think it relies on battery. I think it's fram or something similar.

Oh good I hope so. I hate to lose all my Dark Wizard saves.

Hugh

[APE]

It has a 3V cell battery, likely a CR2032 based on the PCB shot I have. The schematics and the datasheet for the chip say it is a: PD431000A-X 1M-BIT CMOS STATIC RAM. I'd have to say it needs that battery for the SRAM chip.

Though if you're lucky the battery is fine but running out of charge. I have a cart for the SMS of Miracle Warriors from 86 or so that never had the battery changed but still keeps a valid save set.

[l_oliveira]

I made my own backup cartridge with an 512KB SRAM... :lol:

It shows 8192 blocks on the MEGA-CD storage screen (it takes a few for the FAT so it's a bit lower)

This is a capture of the MEGA-CD screen:

:thumbsup:

I have schematics if anyone is interested.

With that much memory one needs nothing more to play all games that ever existed for the three regions of MEGA/SEGA-CD :lol:

[APE]

Been tempted to build one using the schematics I found a while ago but I'm a cross between lazy and now willing to mess up a dozen times due to lack of cash. Good to know I can pop a larger chip in there though.

[ASSEMbler]

I made my own backup cartridge with an 512KB SRAM... :lol:

It shows 8192 blocks on the MEGA-CD storage screen (it takes a few for the FAT so it's a bit lower)

This is a capture of the MEGA-CD screen:

:thumbsup:

I have schematics if anyone is interested.

With that much memory one needs nothing more to play all games that ever existed for the three regions of MEGA/SEGA-CD :lol:

Oh that's funny. Seriously though sega, sram? I wonder if krikzz can whip up a permanent save device.

[l_oliveira]

Oh that's funny. Seriously though sega, sram? I wonder if krikzz can whip up a permanent save device.

1991, buddy. I don't think that in 1991 FRAM or FLASH were commercially viable ... :thumbsup:

[ASSEMbler]

1991, buddy. I don't think that in 1991 FRAM or FLASH were commercially viable ... :thumbsup:

Some sega carts had f-ram. I thought the memory cart was big f-ram, as it was so expensive $69.

[hugh]

Some sega carts had f-ram. I thought the memory cart was big f-ram, as it was so expensive $69.

Wow it was that high? I bought it for $25 new at a movie rental place, back when they where still making games for the SEGA-CD. I guess they where trying to get rid of it since it was just a RAM cart for the SEGA-CD.

Sucks that it uses a battery though, I guess sometime I will lose all my Dark Wizard saves. :(

Hugh

[Calpis]

I dunno why the SRAM hate... Lots of old games access SRAM very often since there is no penalty. Replacing SRAM with FRAM will only increase the chance rate of failure. Not only will the save be gone but the chip will need replacing. The best solution is SRAM with the occasional backup to computer/another media.

Back in the day FRAM was still pretty cheap (SRAM will always be the most expensive memory) but FRAM densities are very small. The FRAM in Sonic 3 for example is only 512 bytes.

I think the 1M of SRAM in the backup cart is pretty sufficient since a 64 byte block packs 512 bits which is plenty for item/stage/time/score info for most games. Arcade style games could need a couple blocks if a dozen long scores are kept and obviously RPGs could use a dozen blocks per save heh. Maybe games aren't very efficient with their saves, dunno, but 1M seems like a lot!

[l_oliveira]

But Calpis, it's 1Mbit, not 1MByte :)

Mine has eight times the memory of an official SEGA RAM backup cartridge.

[APE]

I'm tempted to go pull out my dead SCD2 mobo and see what chip it used for SRAM and then see about finding a larger replacement for it. Why bother with a ram cart when you can have it internal?

:)

[Calpis]

But Calpis, it's 1Mbit, not 1MByte :)

Mine has eight times the memory of an official SEGA RAM backup cartridge.

I know, 1M should be enough though, 16 times as much as the internal RAM :P You're sucking down batteries faster than you need. Do many games use more than a couple blocks? With old consoles (and non-system managed saves) I'm always worried a rogue game will delete all the other saves, I think that should be the biggest cause for concern w/ MCD.

I'm tempted to go pull out my dead SCD2 mobo and see what chip it used for SRAM and then see about finding a larger replacement for it. Why bother with a ram cart when you can have it internal?

:)

Internally it uses a 6264. You can put in a 62256, any higher will be a bit of reworking. The next largest sizes are 628128 and 628512 which are in SOP packages. The BIOS may also not support any larger sizes like it does for the backup cart.

[hugh]

I know, 1M should be enough though, 16 times as much as the internal RAM :P You're sucking down batteries faster than you need. Do many games use more than a couple blocks? With old consoles (and non-system managed saves) I'm always worried a rogue game will delete all the other saves, I think that should be the biggest cause for concern w/ MCD.

::snip::

Dark Wizard saves take up 70 blocks each. You can only save one game on the SEGA-CD it's self.

Hugh

[l_oliveira]

I know, 1M should be enough though, 16 times as much as the internal RAM :P You're sucking down batteries faster than you need. Do many games use more than a couple blocks? With old consoles (and non-system managed saves) I'm always worried a rogue game will delete all the other saves, I think that should be the biggest cause for concern w/ MCD.


Internally it uses a 6264. You can put in a 62256, any higher will be a bit of reworking. The next largest sizes are 628128 and 628512 which are in SOP packages. The BIOS may also not support any larger sizes like it does for the backup cart.

I'm not sucking extra because the SRAM chip I used is specific for this purpose and it's a modern one at it, too. I have an modified KONAMI SCC cartridge for the MSX, which with an (rechargeable) Sanyo Manganese-Lithium battery (the same one used on the dreamcast) can hold data for two years without being recharged. (I tested it and wow I'm impressed)

As for the internal memory yes the ROM does not support larger storage.