Performa 630 - RAM question

[Kurasiu]

Greetings everyone,

I have a little question regarding the max amount of RAM in Performa 630 (rev B board), as I've read some conflicting information on the net, and like a Mac guru to clear my doubts.

LowEndMac states that I can use a single-banked 64 MB SIMM for a max amount of 68 MB. Other sites claim that only 32 MBs are supported, for a total of 36. I also read on several sites that I can solder a second 72-pin RAM slot and fit it with 16 MB single-banked SIMM (for a total of 52 MB), however there are only 64 solder pads on my board - not enough to fit a 72-pin slot!

So, can anyone please tell me what's the truth? Can I safely put a single-banked 64 MB? Somehow solder a second slot? Or am I stuck with 36, without swapping the board to a Quadra one?

 

[Trash80toHP_Mini]

Folks who say you can solder a 72 pin SIMM socket on there can't count. You CAN solder a 68(?) pin ROM socket where it's unimplemented.  []

 

[Trash80toHP_Mini]

Hi again and welcome aboard! I was almost late to work after posting that curt reply. In your first pic of the component side, you can see how the pin count discrepancy isn't obvious, hence the mistaken assumptions posted about the the virtual world. Your second pic of the solder side shows it clearly. Only the DOS compatible boards have two RAM slots. IIRC those boards lack the vestigial ROM slot provision, which may have added to the confusion.

Differing maximum memory configs stem from Apple's supported configurations at time of release, which doesn't take into account higher maximum configs as higher density memory modules become available later on. There are also single/double banked memory bugaboos to throw into the mix. Not sure how it played out in the 630 series. My Q630 was in a backup role, having never been maxed out as a graphics workstation.   

 

[johnklos]

The Quadra 630 motherboard which has one SIMM slot can take a 128 meg SIMM, for a total of 132 megs of memory.

Any of the "DOS Compatible" Quadra 630, Performa 630, 631, or 640, or the LC 631 should have two SIMM slots. These can take one single sided (single banked) SIMM, up to 64 megabytes, and one dual sided (dual banked), up to 128 megabytes. This can give you up to 196 megs of memory.

 

[Kurasiu]

I was almost late to work after posting that curt reply.

Hope you didn't get into any trouble because of that!

And thanks for the replies, Trash80toHP_Mini and johnklos. What you're saying would suggest that LowEndMac was right, with it's RAM info. Not to mention there's also this video of Performa 630, clearly showing 132 MBs of RAM in the profiler/about box/video's description. I might actually risk getting a single-sided 64 MB after all!

 

[Trash80toHP_Mini]

Nope and you're welcome. Be aware, single-sided and single-banked aren't necessarily the same thing. The former refers to the implementation of memory chips on only the "component side" of a module. The latter refers to the logical arrangement of the memory chips in terms of addressing wherever they may be located. If I ever find my Q630 board, I'm dying to play games with its two banks of memory. Soldered memory is an affliction no to be endured! [}]

 

[Dandu]

The solder pad is for a ROM slot, not for a RAM slot.

 

[Innes]

Did the ROM slot have a purpose?

 

[Trash80toHP_Mini]

It goes something like this: Apple got a major black eye when they introduced the Macintosh II as a 32-bit machine, its "Dirty ROMs" were soldered to the logic board. A class action suit ensued and the IIx and IIcx were released with ROM slot provisions for an easy hardware level firmware fix as was the IIci, which finally had 32-bit cleanliness on board. Mode32, Connectix' patented software product fix was purchased by Apple and released as freeware to alleviate those legal problems and preclude the necessity for hardware based fixes. Apple kept up the practice of installing ROM sockets to ensure such problems could be fixed, usually implemented, sometimes not. By the time DIMM form factors arrived, Apple started making use of the slots with ROM cards as standard equipment, probably to save board real estate along with ensuring flexibility. EEPROM developments and higher densities ended the era of the ROM slot.

That's the way I remember it anyway, anybody got more detail to add or corrections?

 

[Franklinstein]

I thought the Mac II had socketed ROMs; otherwise, how was the FDHD upgrade performed in a cost-effective manner? Not that it was inexpensive as it was but it would have likely been twice the price if a logic board swap was required; may as well do a IIx upgrade at that point.

Otherwise I'd say that's the gist of it. Connectix built fixes for Apple's shortcomings on more than one occasion.

 

[Kurasiu]

Alright, guys, a quick update regarding the matter.

I actually took the risk and bought a 128 MB stick from Keystron, it was delivered today. And guess what? The youtube guy was correct, while every other site (well, minus the LowEndMac, kind of) had the wrong info. My Performa 630 works beautifully with a 128 stick:

Well, now that's what I call a whole lot of RAM.

 

[Trash80toHP_Mini]

I thought the Mac II had socketed ROMs; otherwise, how was the FDHD upgrade performed in a cost-effective manner? Not that it was inexpensive as it was but it would have likely been twice the price if a logic board swap was required; may as well do a IIx upgrade at that point.

You got me there, I must have mixed it up with the IIci, whose clean ROMs are soldered with a socket we all love so much and "select" jumper thrown in for good measure.

Otherwise I'd say that's the gist of it. Connectix built fixes for Apple's shortcomings on more than one occasion.

Yep, that gang in Connecticut rocked.

Fabulous seeing 132MB number come up in that screen! [] So did you get a single or double banked SIMM? Got linkage?

Now I need to find and check my MIA Q630 board to see if the address and data lines for the soldered bank and the two banks (or just one?) on the 72 pin SIMM are a unified bus. Turned out not to be the case in the IIsi, which complicates that memory hack immensely. If the requisite lines can be cut on the floor and patched to a two or four slot, 72pin "SIMM Doubler" then 256MB would be a far fetched possibility. It's certainly a lot more flexible a setup than the 128MB limited(?) 840AV. Memory configurations in the Q630, its 68K cousins and PPC descendants was the wild wild west. Q60 was the Quadra bridge to the world of PPC with so many unique features. Don't think they ever took the series to 256MB, but it sure would be fun to try. [}]

 

[Kurasiu]

Fabulous seeing 132MB number come up in that screen! [] So did you get a single or double banked SIMM? Got linkage?

Got it from ebay. It's a 32x32 double banked SIMM. I've played around yesterday for a while with a variety of different software/games, and can confirm it works very well.