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Finding the right extended/expanded memory for my Dell System 200 286

Bill-kun

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My Dell System 200 286 is in tip-top condition with the exception that I'd still like to max out the RAM. It has 4 30-pin SIMM slots. Under the case cover I find this sticker on top of the floppy drive cage. See SIMM note on the lower left.

Dell System 200 Component Identification - Screenshot 2021-05-05 204458.jpg - Click image for larger version  Name:	Dell System 200 Component Identification - Screenshot 2021-05-05 204458.jpg Views:	0 Size:	141.8 KB ID:	1207678Dell System 200 Component Identification - Screenshot 2021-05-05 204458.jpg - Click image for larger version  Name:	Dell System 200 Component Identification - Screenshot 2021-05-05 204458.jpg Views:	0 Size:	141.8 KB ID:	1207678

I bought a set of quantity 8 of 256 kB. SIMM sticks on eBay. Here is what the listing said.
  • https://www.ebay.com/itm/143364068604
  • "8x 256KB 30-Pin 3-Chip Parity 80ns Memory SIMMs 2MB Matched Set Vintage PC RAM
  • Condition: Seller refurbished
  • Our mission is to provide the highest quality Macintosh parts for your vintage computer restoration projects.
  • ITEM DESCRIPTION: This is a matched set of EIGHT 256KMB 30-pin SIMMs, totaling 2MB. These are parity modules with three chips on one side (other side is empty) This is a fully tested and working set for vintage PC systems.
  • NOTE: Your item may look slightly different than the one pictured here.
  • TESTING: The item was tested in our shop and works perfectly!"
I inserted 4 of the sticks in the correct direction and tried booting, but the computer would not boot. I removed the sticks and it booted fine.

The 4 SIMM sticks inserted - Screenshot 2021-05-05 212316.jpg

Is installing RAM in a 286 PC as simple as putting it in the slots and booting up, or am I missing something? Is it possible I was sent Mac SIMM RAM instead of PC RAM, or even some other thing, like Amiga SIMM? Is there any difference between PC SIMM RAM parts and Mac SIMM RAM and any other SIMM?
 
Last edited:

GiGaBiTe

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There's no difference between Mac and PC 30 pin SIMMs, they're the same. The only odd man out is IBM 30 pin SIMMs, which do have different pinouts on specific machines.

The only thing that could be causing issues is the fact it only has two memory chips (the 3rd smaller one is for parity) instead of eight or 9 chip modules (the 9th again being for parity.) Some machines don't play nice with high density memory modules that use four or two memory chips on them. Parity is another thing, some machines don't like parity memory.
 

Bill-kun

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Given that the memory stick diagram shows 9 chips, I will assume I need sticks of 256 kB. with 9 chips each. Now to search for them.
 

kc8eyt

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According to Total Hardware's motherboard information the Dell 200 system requires parity chips:
DRAM CONFIGURATION
Size Bank 0 Bank 1 Bank 2 Bank 3
1MB (1) 256K x 36 NONE NONE NONE
2MB (1) 256K x 36 (1) 256K x 36 NONE NONE
3MB (1) 256K x 36 (1) 256K x 36 (1) 256K x 36 NONE
4MB (1) 256K x 36 (1) 256K x 36 (1) 256K x 36 (1) 256K x 36
4MB (1) 1M x 36 NONE NONE NONE
5MB (1) 1M x 36 (1) 256K x 36 NONE NONE
6MB (1) 1M x 36 (1) 256K x 36 (1) 256K x 36 NONE
7MB (1) 1M x 36 (1) 256K x 36 (1) 256K x 36 (1) 256K x 36
8MB (1) 1M x 36 (1) 1M x 36 NONE NONE
9MB (1) 1M x 36 (1) 1M x 36 (1) 256K x 36 NONE
10MB (1) 1M x 36 (1) 1M x 36 (1) 256K x 36 (1) 256K x 36
12MB (1) 1M x 36 (1) 1M x 36 (1) 1M x 36 NONE
13MB (1) 1M x 36 (1) 1M x 36 (1) 1M x 36 (1) 256K x 36
16MB (1) 1M x 36 (1) 1M x 36 (1) 1M x 36 (1) 1M x 36
Note: Sizes shown here are in addition to 640KB factory configured on the main board.
 

kc8eyt

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I would install four 9-chip (parity) 1MB chips myself. Much easier to find. According to the chart above it looks like 256K chips are not even supported.
 

Bill-kun

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According to Total Hardware's motherboard information the Dell 200 system requires parity chips:
DRAM CONFIGURATION
Size Bank 0 Bank 1 Bank 2 Bank 3
1MB (1) 256K x 36 NONE NONE NONE
2MB (1) 256K x 36 (1) 256K x 36 NONE NONE
3MB (1) 256K x 36 (1) 256K x 36 (1) 256K x 36 NONE
4MB (1) 256K x 36 (1) 256K x 36 (1) 256K x 36 (1) 256K x 36
4MB (1) 1M x 36 NONE NONE NONE
5MB (1) 1M x 36 (1) 256K x 36 NONE NONE
6MB (1) 1M x 36 (1) 256K x 36 (1) 256K x 36 NONE
7MB (1) 1M x 36 (1) 256K x 36 (1) 256K x 36 (1) 256K x 36
8MB (1) 1M x 36 (1) 1M x 36 NONE NONE
9MB (1) 1M x 36 (1) 1M x 36 (1) 256K x 36 NONE
10MB (1) 1M x 36 (1) 1M x 36 (1) 256K x 36 (1) 256K x 36
12MB (1) 1M x 36 (1) 1M x 36 (1) 1M x 36 NONE
13MB (1) 1M x 36 (1) 1M x 36 (1) 1M x 36 (1) 256K x 36
16MB (1) 1M x 36 (1) 1M x 36 (1) 1M x 36 (1) 1M x 36
Note: Sizes shown here are in addition to 640KB factory configured on the main board.

The chips I bought on eBay are 256K parity chips.

Can you please give the link of where this table came from? I can't understand what it means by 256K x 36. What does the "x 36" mean?

I don't find a Total Hardware vintage computer site. I do find Tom's Hardware. Is that what you meant?

I would install four 9-chip (parity) 1MB chips myself. Much easier to find. According to the chart above it looks like 256K chips are not even supported.

I can try 1 MB. chips if the 256K ones don't work, but according to the table above (not to mention the photograph of the manufacturer's sticker I showed) what makes you say it doesn't support 256K chips? It sure seems like it's explicitly stating that it does.
 

SomeGuy

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Marietta, GA
I believe the source in question is this th99 page:
https://th99.infania.net/m/C-D/30935.htm

However, the chart is nonsensical because it has the slots on the motherboard labeled "bank" 0-3. It looks like it might mistakenly think it uses 72-pin parity (x36) simms.

According to this:
https://books.google.com/books?id=Ob...200%22&f=false

The System 200 should have 640k built on to the board, supports 4mb of additional ram on the motherboard, and then up to 16mb ram if a ram expansion card is installed.

So the 4 slots on the motherboard might be be "bank 0", and then 12 slots on an expansion card, as banks "1-3". But that still does not make perfect sense, as that is a 286, and it should be possible to add just two SIMMs, making the 4 motherboard slots "banks" 0 and 1.

At any rate, if you don't have the expansion card, then logically it sound like 256 or 1mb parity SIMMS aught to work, for up to 4mb of RAM plus the built in 640k.
 
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