Soldering more RAM onto an LC

[olePigeon]

I was just wondering. On the LC motherboard there are empty RAM sockets for onboard memory. Could someone solder additional chips (say, take some from a broken LC motherboard) onto the motherboard?

Anyone try this? Is there a reason why this wouldn't work?

Also, even if it did work, would it be able to have more than 10MB of RAM?

 

[Trash80toHP_Mini]

Don't take this personally if you already know all of this, please.

I've never had one, but I'd check for a ROM SIMM on board first, then I'd describe the IC Package size and pin count. Those might be alternate ROM locations, unimplemented VRAM pads or the actual ROM pads if yours shipped with a ROM SIMM.

Just a few possibilities, lots of folks assume pads are for what they'd like them to be . . . they're often not. :-/

Check the DevNotes on the LC for Apple's lamed ceiling limit (comes with the standard "feature package" on all low-mid range Macs

) for the LC. If it's 10 MB, you'll need to use it as virtual memory even if the pads are for additional RAM.

Look for GAMBA in the Peripherals Links Project for the DevNotes.

 

[olePigeon]

Nothing personal taken, I don't even know half the things you just said. I was looking at the motherboard and there are empty pads between RAM chips. On the LC II the motherboard looks nearly identical, except those pads are all filled.

It was just a thought.

 

[Scott Baret]

The RAM limit is a pain on early LCs. If you add two 4MB SIMMs to an LCII, you should have 12MB (4MB onboard), but will only be able to use 10MB of that. Unlike the 32-bit dirty Macs, which could only see 8MB without special software, there's no Mode32 equivalent to let you use that RAM.

I recommend just leaving the 2MB onboard on your LC and getting a pair of 4MB SIMMs to populate the RAM slots. The 512K VRAM upgrade is also worth it if you're going to be using anything 640 x 480 or larger and want 8-bit color. (With the stock 256K, the only monitor capable of displaying 8-bit color is the 512 x 384 12" RGB, which was often sold alongside LCs and LCIIs and is contoured to match the case perfectly).

The LC II, by the way, uses what is essentially a modified LC I board. The key differences between the internals of the LC and LC II are:

-68030 in LC II vs. 68020 in LC; both run at 16MHz and have a gimped data bus, limiting their speed (the LCs have a 16-bit data bus; the II and IIx had a 32-bit data bus, which allows them to run faster despite identical clock speeds)

-4MB soldered onboard the LC II vs. 2MB on the LC

-No second floppy connector/case slot on the LC II

-Different fan and speaker assembly (interchangeable with later LCs, making a logic board swap to an LC III/III+/475 easy)

-Presumably both have identical minimum system versions, although I've never tested or read about 6.0.6 on the LC II (6.0.7, contrary to popular belief, does run on an LC II--I run it on mine)

 

[Bunsen]

Also, even if it did work, would it be able to have more than 10MB of RAM?

Doubtful - that's likely a ROM restriction.

-4MB soldered onboard the LC II vs. 2MB on the LC

And still only a 10MB RAM limit :-/

you'll need to use it as virtual memory

How would you even do that though? The Virtual Memory driver is looking for a hard disk.

 

[olePigeon]

How does the Presto Plus bypass the 10MB RAM limit? If I had to guess, it uses its own ROM and bypasses the LC completely.

 

[Gorgonops]

My limited understanding is it's not a ROM limitation, it's black magic badness with the hardware memory controller. CPU upgrade cards which include their own SIMM sockets thus work around it by having a "private" memory bus on the card upstream of the "broken" one.