Apple IIGS Memory Expansion Card Chips?

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Apple IIGS Memory Expansion Card Chips?

Hiya folks!

 

I am curious, if I want to add extra chips to my Apple memory expansion card where would I find those chips? It doesn't say in the manual what they're called or where to get them...

 

I have the top row full, but the bottom row is completely empty. So, I believe that means the card only has 256KB on it.

Thanks everyone!

 

~

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I bourgh some from Jameco 

I bought some from Jameco 

 

https://www.jameco.com/z/41256P-10-Vishay-IC-41256P-10-DRAM-262-144-Bit-262-144x1-100ns-5V-Low-Power_2290567.html

 

 

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Or look at a modern GS RAM

Or look at a modern GS RAM card...  Garrett's Workshop has an 8MB card for $40.  That's not much more than filling your old 1MB card.  And the new cards use many fewer chips so they use less power and generate less heat.

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Here's where you can find

Here's where you can find Garret's Workshop:

 

http://www.garrettsworkshop.com/

 

https://www.tindie.com/stores/garrettswrkshp/

 

 

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Except for the fact that has

Except for the fact that has been out of stock for 9 months or so. Probably due to pricing or availability of the Altera Max II used on it. If I had to guess. 

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nick3092 wrote:Except for the
nick3092 wrote:

Except for the fact that has been out of stock for 9 months or so. Probably due to pricing or availability of the Altera Max II used on it. If I had to guess. 

 

Bummer...

 

I really like the GW stuff.  I hope they are able to make more.

 

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It's a lot more expensive

It's a lot more expensive than the GW one, but I'd prefer this to an original Apple card...

 

https://www.ebay.com/itm/New-GGLABS-RAMGS-8-Apple-IIgs-8MB-memory-expansion-8M-RAM/401053959389

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I purchased the 4MB expansion

I purchased the 4MB expansion card from Brielle. It is a beautiful card and it works perfectly.

 

I am asking about the original Apple branded card because it's such a unique card in the history of things. From what I can tell, Apple made this card and it got eclipsed by the competition so quickly that they essentially never bothered to update it again, correct? So, in reading through the manual I was curious how and where one would go to upgrade the card if they so chose to add additional chips at a later date. Presumably, one would just go to their Apple dealer and ask, but that's no longer an option :)

 

So, I appreciate the above link... but I am still curious as to how you figured out which chips fit into that board? How would one have known that bit of information?

 

Thank you all for your expertise!

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I wouldn't have gone to a

I wouldn't have gone to a dealer, I would have ordered the chips from somewhere like JDR or JameCo.  That was much cheaper.  I bought additional chips from one or the other of those two back in the day to fill up my AE RAMWorks II card for my //e.  I think those might have even been the same chips the Apple RAM card for the GS used.

 

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Going to go out on a limb here...

I'm guessing the suggestion of which RAM chips to get was simply based on what RAM chips were already on the board.

Clearly visible are KM41256-12 RAM chips, which are generic 256K x 1 bit RAM at 12ms. Anything with the same bits and equal or faster access will work fine dropped in there as replacements, and Apple is unlikely to have designed a card that takes one type of RAM for the first bank and a different for the other. 

(In fact it looks like it's already been upgraded once! There's a bank at the back of the card of soldered on TI RAM.)

 

Chesh

 

 

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Back in those days BBSes and

Back in those days BBSes and USENET were the online places to go for information about chip compatibility.

 

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All these numbers and terms

All these numbers and terms aren't very clear about how much memory is stored in each chip, though. Or is it just me?

 

IC 41256P-10 DRAM 262,144-Bit (262,144x1) 100ns 5V Low Power

 

What does "262,144-bit" refer to? 8 chips are required to total 256K, so therefore, how is it clear that "256K x 1" means 8 chips? Shouldn't each chip then hold 32K? How come that isn't denoted anywhere?

 

It seems mysterious to me that this would be obvious to anyone buying the chips at the store. I'd see "256K x 1" and would assume that meant "each chip holds 256K."

 

Thanks everyone~

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It was understood that x 1

It was understood that x 1 meant you needed 8 chips...  or 9 for most PC clones since they usually had parity.

 

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These cards came with 8 chips

These cards came with 8 chips soldered on giving it 256k. Your card has 8 more chips installed which means your card has 512k on it. There’s two jumpers. The first you add when upgrading to 512k. You also add the second when upgrading to 1mb. There’s no allowance for having 768k.

 

Back in the day most places that sold RAM would have known what you needed if you told them you were buying it for a IIgs memory card. There was also a lot of mail order. All the Apple II magazines has companies that sold RAM chips amongst other things

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clamm wrote:All these numbers
clamm wrote:

All these numbers and terms aren't very clear about how much memory is stored in each chip, though. Or is it just me?

 

IC 41256P-10 DRAM 262,144-Bit (262,144x1) 100ns 5V Low Power<

It's actually there in the chip name. There's a standard (Gotta love standards. There's so many to pick from)

The first digit is whether it's SRAM or DRAM. 4 for DRAM, 6 for SRAM, so this is a DRAM chip.

The second digit is how many "bits wide" the chip is. Ie how many data pins are there exposed. Commonly it'll be 1 or 4. I suspect there's 8 but I've never seen it. So  41 series is 1 bit wide DRAM. You can only read / write 1 pit per chip. I have systems using 44 series RAM (Commodore 64 later models) so they're 4 bits wide and you can read or write a 4 bit nibble per chip.

The rest of the numbers to the hyphen is the number of "cells" of memory there is. Now this is tricky, because you need to multiply the number of "bits wide" the RAM is by this number to get the actual bits, and then by 1024, because it's a measurement of kilocells. (Confused yet? Took me YEARS to be able to read these). So this chip is 256k x 1 bit wide, thus 32 kilobytes of potential storage.

Now remember that second digit? This is where that becomes significant.

The RAM on late model C64s was 4464 RAM. Thus DRAM, 4 bits wide, 64k cells of 4 bits wide. Thus each of these was also 32 kilobyes wide. The difference? Whereas 41256 needs eight chips to make an 8 bit datapath, 4464 only needed 2 chips to to make the full 8 bit datapath.

 

Now, not all systems have 8 bit datapaths. I have an Archimedes (Sadly, currently not working as well as it should) that has a 32 bit wide data bus.  It has an absolute sea of 411024 RAM on the motherboard (The nomenclature is slightly different because it was sourced by a different manufacturer, but it's equivelent). 

So, DRAM, 1 bit wide, 1megabit.  But it needs to read it 32 bits at a time, so there are 32 of them, for a grand total of 4MB of RAM.

 

Chesh

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Chesh, This is precisely the

Chesh,

 

This is precisely the kind of detailed explanations that help me understand things. Thank you very much for taking the time to walk me through that standard and history.

 

Incredibly helpful!

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SDRAM

Thank you for your explanation!  I have a question, if you please.

 

I have a 670-0025 IIgs expansion card and understand the 41256P-10  is a suitable chip to populate the rest of the card.  The eight chips on the card are TMS 4256-15, which to my intuition would indicate 150 ns.  Would the difference in speed (vs. 100 ns) be significant?

 

Thanks,

Paul

 

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Faster RAM is usually OK

Hey Paul,

The faster RAM should be OK. I'd certainly be prepared to risk it. It would simply be running at a slower speed.

 

Chesh

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I just pulled 768k off of my

I just pulled 768k off of my old IIgs memory card to put it on an Apple "Slinky" card.  The chips I pulled from the IIgs card are Samsung KM41256AP-12, so 120ns.  The 256k that is soldered onto the board are the same chips.  100ns should be fine, as has been said, they just won't be pushed to run at full speed.

 

But honestly, I'm far happier with the modern 8MB card I have in there, it probably draws less current than the stock Apple card with only 256K on it.

 

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