Upgrading dreamcast ram

[Masta-G]

Some rumours go that it has been done before.
Replacing the current ram chips with bigger ones...
I dont know if the offical bios will map more memory but it could be useful for homebrew or linux stuff.

Some info would be nice

[semicolo]

If I remember well, what's already been done was adding memory chips on top of those existing and adding controls. Could only be used with homebrew, but seems a lot of trouble to me, buy a modded xbox instead.

[quzar]

absolutely nobody has done this before. the closest thing that has been done was a second switchable bios.

[Masta-G]

I see...
Well I opened my dreamcast and it seems it uses the HY57V161610DTC-8 chip running at 125MHz (see http://www.mcu-memory.com/datasheet/...v161610dtc.pdf)
I think the 4 chips on the left side of the cpu are used for the main memory which means they should be 4megs each.

I'm good at soldering and I was thinking of removing the actual chips and replacing them with bigger ones...

I don't have much hardware knowledge so I wonder if there's anyone who can tell me what chips to get and which ones to replace to upgrade only the main ram and maybe video ram if its possible.
It's ok if it gets fuxxed since its my spare dreamcast.

Thanks for the replies

[quzar]

http://www.dreamcast-scene.com/index...dwareRevisions

The four chips to the left of the CPU are not main memory, they are each 2mb vram chips. The main memory is in two 8mb chips.

About the only thing you can do is replace them with lower latency chips, but as my hardware database (which is incomplete) will show, from the first to last dreamcast there were already many revisions in chip latencies.

[Masta-G]

Well my dreamcast console is Model No.HKT-3030 PAL-E
The mobo says: SEGA 1999 171-7965C KATANA MAIN VA1
The main memory are indeed two chips: Toshiba C83591 9929KBD TC59S6432BFT-10 (both the same).
Do you think its possible to replace them with 2 new chips both 32megs (if they exist)?

[Masta-G]

I'm not that much of a hardware developer...
So I really dont know what kind of tsop I need to replace the current chips with.
But if someone could find that out and point me to the right chips to buy then ima try it I have the solder equipment and a multimeter here.

[quzar]

Unless the bios is rewritten, adding two new chips won't have any effects.

[semicolo]

sorry I must have mistaken the bios mod with a ram upgrade.

It would probably be needed to add an address line, don't know if it'd be possible.

Do you have cms soldering equipment? (else it's rather hard to desolder ram chips).

[Masta-G]

Well I have a 15W soldering iron with 2mm tip, solder and flux.
I'm using a magnifying glass and im practicing on regular pc ram.
I've successfully removed and resoldered one of the chips (about the same size as the dc ram chips).
I know I need to rewrite the bios in order to make it map the full ram of the new chips.
But I think the linux kernel can map the full ram even if the bios didnt map it, that was the reason why I wanted to upgrade ram. Regular dc games were built for 16megs anyways.

EDIT: The linux-sh kernel does its own memory mapping, in fact it doesnt rely on the bios at all.