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4400/7220/Tanzania Clone VRAM

jessenator

Well-known member
So from what I've gathered, the ubiquitous 2 MB (slow) EDO VRAM DIMM is so slow that going beyond the 2 MB is pointless. The upgrade was a 4 MB SGRAM DIMM, which I have yet to find in the wild—probably long-gone. The repair manual mentions other values as well, for both configurations, of 1-4 MB, which is interesting.

ABd0AlPm.jpg.d77ec8e55bbfc60807c7c39f94ba2d27.jpg


What I'm wondering is this: can one desolder the EDO VRAM and install SGRAM ICs in their place? I can't find a p/n for the SGRAM that was used contemporaneously, or even what to look for as far as specifications to accomplish this. Also, I wonder if this is a dead-end simply because of the arrangement. Now, this is all coming from a non-engineer, so forgive me if I'm way off base. I managed to find what I think are images of the SGRAM DIMMs, and they look much different (the packages are different?) from the 2 MB DIMM:
 

This one from MemoryTen (vs Memoryx, yet the same company??) but though it shows it in stock, you try to add to cart and it gives you a sorry message.

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This one was from a google image search linking back to an Argentine ebay-like site, but no evidence of the module still being up and for sale.
I2SFUeV.jpg.3af2629dbd4a618dd0f8724f470d2d02.jpg


That last one might be enough in the resolution department for eagle-eyes, but I still can't make it out :/  

But if it was possible to find appropriate packages of the SGRAM to fit the more commonly-found DIMMs, is it even possible to turn a standard DIMM into the improved one? And if it is, then is it possible, or of any value, to bump the VRAM even higher? 

 

jeremywork

Well-known member
There’s so very nearly enough pixels to make out... but nothing I’ve shapeshifted it into has yielded a google result.

I tried compositing the two together, flanked by the originals to give my brain as much to work with as possible. Using a smartphone and holding it at different angles/zoom levels may help...

041956D2-C062-4C63-9E8B-0A36866BAD66.jpeg
 

CM4132627143-10?

KMU3262Y1A3-10?

Wish I had the answer but maybe this image will click better for someone else. 

 

Franklinstein

Well-known member
Unfortunately, no, nobody offered SGRAM in a package compatible with those EDO DRAM modules, so simple chip-swapping isn't possible. Aside from the 4400 and various clones based on that logic board, I don't think anything else used that VRAM module. But I think this is also true of the VRAM DIMMs in the 7 and 8 series models: exclusive to Apple and long out of production.

One of our resident geniuses could probably build a VRAM board that plugs into the 4400's VRAM slot and accepts the later ATI SODIMM-style VRAM modules, but that's way beyond my ability.

But yeah, I venture most people simply installed a new video card rather than trying to upgrade the VRAM on these so they're kind of hard to get. I would probably only bother looking seriously if I had a PC Compatibility Card and was going to use the GIMO pass-through for simplicity. Is that what you're doing?

 

jessenator

Well-known member
Unfortunately, no, nobody offered SGRAM in a package compatible with those EDO DRAM modules, so simple chip-swapping isn't possible.
Damn. I feared as much. Well I did find a 4MB module here for $40, which, is steep like you mentioned in another thread of mine on the 4400 I think :)  .

I wonder. I know that the Mach64 went up to about 8 MB according to the wikipedia page, and I'm guessing it wouldn't benefit really from more than that. The Rage II on the higher end might, but I wonder how large the market would be... Thinking of the other projects on here, more folks have an SE/30 and want to add a better cache adapter to it than there are people who have Macintosh Portables, and special SCSI2SD boards are made for those. So you'd imagine the ownership of Tanzania-based machines is lower than that even... as someone on the IRC mentioned, "seems like it'd be cheaper just to slap a Rage128 in there" and they're probably right :lol:  

But if there's ever any larger scale desire for a standard one of those ideas would be ripe, for sure.

 I would probably only bother looking seriously if I had a PC Compatibility Card and was going to use the GIMO pass-through for simplicity. Is that what you're doing?
While that is a problem for my 4400/7220 board (because every DA-15 to DB-15 adapter I've ever tried has never worked properly), the StarMax boards all have DB-15, which makes my multi-sync  flat panel displays work just fine. The biggest thing I came to discover is setting up a proper profile for what display you're using in the PC Setup control panel. I didn't think about this and was royally pissed when the left or top was completely cut-off on the DOS side, no matter what I did on the monitor itself. Even my 13" High Resolution AppleColor RGB blah blah this name is too long, fixed-640x480 DA-15 monitor had issues.

Edit:  Even though the Mach64 on the card itself has VRAM, it doesn't use system VRAM does it? there's a weird expansion type port on the card, but I don't know what it's for. Some folks on Vogons theorized it might be for an ISA expansion that was never developed, but IDK.

 
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Franklinstein

Well-known member
Damn. I feared as much. Well I did find a 4MB module here for $40, which, is steep
That's probably a bargain compared to original MSRP.

I wonder. I know that the Mach64 went up to about 8 MB according to the wikipedia page, and I'm guessing it wouldn't benefit really from more than that. The Rage II on the higher end might, but I wonder how large the market would be...
Several computers used the Tanzania/II based board, including some non-Mac PPC workstations, so I imagine someone could sell at least 100 adapters if they were built. If they were <$20/ea, I'd buy two, at least. The 4400-VRAM-slot-to-ATI-SODIMM adapter shouldn't be very expensive: you're basically just building a small board and sticking a SODIMM socket on it into which the end user will install an appropriate SGRAM SODIMM. The adapter board should be simple in theory: just run the appropriate lines from the slot pins to the new socket and you're done. I doubt you'd even need any additional resistors or capacitors or other discrete components since they should already be in place on either the logic board or on the SODIMM module. 

Even though the Mach64 on the card itself has VRAM, it doesn't use system VRAM does it?
I don't know which model PC Compat card you have, so I can't say exactly what you may be looking at, but all of them from the original Houdini to the last 12" card have dedicated video memory, usually in the form of EDO DRAM. The PCI models should have at least 1MB each, with a couple empty sockets for expansion to 2MB of EDO DRAM on the 12" model. 

 

jessenator

Well-known member
The PCI models should have at least 1MB each, with a couple empty sockets for expansion to 2MB of EDO DRAM on the 12" model. 
Yeah, that's what mine are (PCI). I upgraded one of them (the P133) to the max 2 MB. So I'm guessing on the PC side it only uses what's on the card (I don't recall specific numbers, but at above 640x480 you couldn't get true-color) 

The adapter board should be simple in theory:
My knee-jerk vote would be for a 90* adapter, but looking at it again just now, the module is well past the height of the PCI mounting, so no worries about it being vertical/in-line I guess.

If anyone with the technical prowess is lurking, I'm happy to lend a DIMM and/or Tanzania logic board to the cause.

 
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