VOGONS


First post, by yourepicfailure

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I've been reading through these boards and others, and well I think I might as well share to help benefit the T3100SX community.
Some folks out there have been wanting a few pics of the proprietary ram card. Well, the fact is, there is not one single design. I have four different versions of the ram card with each also using different sets of dram chips.

Hopefully these can be of use. I couldn't get a perfect focus no matter how hard I tried, so I apologize for the blurriness. But they should be detailed enough to get something out them.
https://mega.nz/#F!GKAQDaLC!UcvC70HvJetX2ZwYeGWfHg

As you can see, each version is of different quality and design depending on the manufacturer. However, Type II reveals the ram modules all use a KEL 8900 series connector. These connectors are actually still manufactured:
https://www.kel.jp/english/product/product_de … d=376&p_cont=39
The catalog PDF has the most detail.

They appear to be 2 layer boards and each of the modules vary in size. I would not, however, stray more than 65mmx41mm.
If you need additional details, please ask.
My fourth board is a stand-by in the event one of the other modules fail. If someone wants to borrow it for further study, that can be arranged.

Reply 1 of 17, by derSammler

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What's the background to this? I have a box of maybe one hundred RAM modules for Toshiba laptops incl. the 3100. Are these rare? Tried to sell these many times but no one ever wanted them.

Reply 2 of 17, by yourepicfailure

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Ones for the t3100sx are some oddball proprietary modules. Most machines posted about don't have more than the stock 1mb.

If you have any specifically for the SX, I'd like to get in touch with you.

Reply 4 of 17, by yourepicfailure

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Interesting. Either they aren't that hard to find and a lot of machines have ram cards or nobody cares enough about the machines to shell out money folks are offering them.

I do remember them popping up frequently on ebay DE but never on ebay US, so I guess it's a regional thing.
If you're willing to take an offer for it, I know a beautiful DE model T3100SX who would be happy to take another 2mb of ram.

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Reply 5 of 17, by derSammler

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Maybe I just had luck with that bag full of proprietary Toshiba RAM modules. 😉 Demand for them isn't that high it seems however. Could be that not too many people are collecting Toshiba laptops here.

I plan to get one of these plasma display-equipped Toshiba laptops at some point as well, so I better keep the modules for the 3100sx and 3200, just in case I score one of these models in the future.

Reply 6 of 17, by jaZz_KCS

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The T3200SX uses normal 30-pins though, I do not know about the T3200. That being said, sourcing compatible memory bars for this model that is compatible in terms of speed and parity is a real pain. (T3200SX)

Reply 8 of 17, by yourepicfailure

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dersammler,

I'd steer clear of a t3100sx unless it's shown functional. The internal power board is full of big, juicy caps and most of them spilled years ago and wrecked havoc. That is if the resume battery (5 aaa nicd cells) or main batteries haven't leaked already. Usually these old machines stored poorly, making it even worse. Then add how everything on the unit is proprietary.
These reasons likely why not so many want to take the risk and toy with one, making demand for the parts low.
And those with fully functional units (myself included) are keeping these to ourselves.

I'll probably go in and solder 512k chips into my modules to get that extra 6mb. Luckily they're all surface mount so it should be easy.

Reply 9 of 17, by derSammler

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yourepicfailure wrote:

The internal power board is full of big, juicy caps and most of them spilled years ago and wrecked havoc.

I'm totally aware of that. I own a 1200XE which also has such a power board. Recapped it and all was fine.

Reply 10 of 17, by yourepicfailure

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In a lot of cases, yeah that will do. But other times the things spilled inside while the unit was in storage unnoticed and left like that to rot. Then add the amount of nicd batteries concentrated in one area.

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Photos of a T3100sx a friend purchased against my warnings after thinking mine was "cool." Damage definitely not the worse, but still pretty bad. Those ports will need some help. Plus, two of the power board's screws were corroded to the point where the heads no longer accepted a screwdriver tip and needed to be drilled.
He honestly thought it was fix some ribbons and plugs and be all done and even thought it was in great shape considering the age.
Then I place it next to mine and he goes "Oh."

However, derSammler if you do decide to purchase a T3100sx, send me an email or a pm. I have the complete 3 volume user's manual set for the unit in DE and I'll be happy to scan the books for you.
I'll have to give you the email address I check constantly.

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Rearing back on topic, my friend's unit did come equipped with 2 2mb modules. So I'm starting to think these ram modules appear to be more common sold within the units than sold separately today.

Reply 11 of 17, by NotebookKiller

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Hello. Can I do some almost off topic necroposting here? I've purchased a dead T3100SX from ebay about year ago. Internal power supply is completely dead - ^$%$$% leaky capacitors. I've used some PicoPSU to power it up and now working on DIY internal PSU. But, let's get back to topic. Look at the attached pictures. Yes, it's 13 MB memory installed. My laptop had a 2MB module installed. I've replaced 4x256k chips to 4x1m (and added a wire for A9 line), but the memory increased from 3mb only to 5mb. Challenge accepted. I've reversed the module, traced a new PCB (one for two memory slots), soldered 16pcs of 4x1m chips... no luck. I've added some 74xx logic to RAS, CAS and A9 lines... no luck. Seemed that it needs some "non-square" memory array chips... and I found them. New PCB, 8x2m chips soldered... no luck. Module with 2 chips is only 1mb. Module with 4 chips - 2mb. OK... let's add some more. 8 chips. Guess what? No. Not 4mb. Still 2mb. What the? It's interesting. The memory array is 2CAS by 4RAS per slot. But... number of RAS's used depends on the size of chips found by chipset. So with 2m chips the chipset turns off 2 RAS lines, and half of array is lost. So maximum size of module is 4mb. And my 2-slot frankenmodule with 16 chips doesn't need any 74xx logic. Just use right RAS lines for memory array. And... it's 8mb on 2 slots. And updated 4mb module on third. Now I'm going to design a final 1-slot 4mb module PCB. Does anyone need such stuff?

P.S. connectors seem to be quite rare, I've desoldered some similar ones from rackmount APC smartUPS, and then filed them to fit (old russian tradition).
P.P.S. I've tried some EDO chips, and they worked.

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Reply 12 of 17, by yourepicfailure

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Certainly, I'm interested. I attached a PDF catalog with the connector, although I can't remember what the product code is.
KEL made most of the connectors in these Toshibas.

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Reply 14 of 17, by ferrytale

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yourepicfailure wrote on 2022-04-23, 02:06:

Certainly, I'm interested. I attached a PDF catalog with the connector, although I can't remember what the product code is.
KEL made most of the connectors in these Toshibas.

Hi there. I think this is not the exact connector toshiba is using!
The right one is KEL 8900 Series. For the modules one could use

8901-050-177S (too wide with the flanges, but you can break them off)
8903-050-177S

link to the actual datasheet:
https://docs.rs-online.com/41a7/0900766b8153af0d.pdf

😀

Reply 15 of 17, by ferrytale

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NotebookKiller wrote on 2022-03-25, 11:59:

So with 2m chips the chipset turns off 2 RAS lines, and half of array is lost.

Thanks for this valuable information.
I built my own memory-module for the T3100SX as well these days and faced similar problems.
According to the available signals:
D0-D15
A0-A9
/RAS0-/RAS3
/CASL
/CASH
I thougt, it should be possible to adress 8MB per module (1M(A0-A9)x2Byte(D0-D15)x4(/RAS0-/RAS3)).
So i designed a prototype-pcb with 4 chips, each 1M x 16 = 8MB.
The module worked at first try, but only 4MB had been recognized by the T3100SX.

Now your suggestion, that only 2 of the 4 /RAS lines are getting used is very interesting.
It means, instead of making another module, I just have to take 2 /RAS lines from the next RAM-connector and connect it to the unused chips on my 8MB-Module.
I will try it this evening.
😀

20220606_162730.jpg

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Reply 16 of 17, by ferrytale

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Yeah, it works! NotebookKiller was right. With the use of 2MB-Chips only the lower two /RAS-lines are supported at each connector.
I just wired the other 2 chips to the lower /RAS pins from the next connector and 8MB of RAM were available! Cool.

So with 4MB per Module and as it is told in the T3100SX Manual you get a maximum RAM of 13MB.
But i guess thats just because one of the 4 banks is the onboard-RAM, which is only 1MB.
What if one desolders (or disables) the onboard-chips and connects another 4MB-Module to this bank?
My idea would be to simply rewire the /RAS lines to 2 of the RAM-connectors on the Logicboard to make two 8MB modules work!
This way it should be possible to get 16MB of RAM, which is the real maximum for a 386SX.
I already did a similar mod to my T3200SXC, that now is able to handle usual 4MB 30pin SIMM modules.

Reply 17 of 17, by ferrytale

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ferrytale wrote on 2022-06-07, 13:21:

What if one desolders (or disables) the onboard-chips and connects another 4MB-Module to this bank?

O.K. this is not working. Wiring the two /RAS signals from the onboard RAM to a 4MB module will also just result in 1MB of RAM.
But it was worth a try. 😀