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Inboard 386/PC 2mb expansion CLONE

I received my new board today, still waiting on the other components before start putting it together. Love the new board looks amazing!
 
Sorry I'm late to the party here. Someone asked me for a picture of mine and after I dug it out, I realized it had memory expansion on it. For the current expansion board design you guys are working on, was there an original memory expansion that looked like that? Mine is just a flat board with lots of DIP RAM. From my count, it's 2MB. Hald is MT RAM so I'm a little worried about that working but it's there at least.

Sadly, the40 pin CPU connector end on the cable is missing three pins so I'll have to source a replacement DIP to IDC connector to try anything. I was just curious.

IntelInboard386.jpg

Santo
 
snuci said:
Sorry I'm late to the party here. Someone asked me for a picture of mine and after I dug it out, I realized it had memory expansion on it. For the current expansion board design you guys are working on, was there an original memory expansion that looked like that? Mine is just a flat board with lots of DIP RAM. From my count, it's 2MB. Hald is MT RAM so I'm a little worried about that working but it's there at least.

Sadly, the40 pin CPU connector end on the cable is missing three pins so I'll have to source a replacement DIP to IDC connector to try anything. I was just curious.

View attachment 1264237

Santo
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You have the 4MB expansion because the 2MB has only one side populated. If you decided later to sell your card. I'm interested let me know. Btw any accelerator card cable should work. Mine came from a breakthru 286 accelerator. Most of them are using the same pin out.
 
harrison.frazier said:
Ok, revision C is tested and working, with assembly instructions! (Note the jumpered resistor spots.. I think they may not be necessary because it works just fine...)

I have 3 blue boards on hand and can order more if there is more interest. I will provide the simm sockets as well. The rest can be found on digi-key.
PM me if you're interested!

View attachment 1264181



Yeah I wouldn't suspect anything that the ram, I've put 30+ hours on my XT with the latest rev and It's solid. I think one of the chips was overdriven by the higher clock signal?

One thing I did was add a fan that blows over the board because these chips get quite warm even when left in the stock configuration! 🔥
Click to expand...
How does this differ from the board I have? Is it simply the 4 mb and 2 mb switch?
 
Latest version suport 4MB or 2MB as far as I know, the switch we don't need if we are using the 4MB version we just have to solder that 4MB connection. The SIMM used are 8x 1MB 30-Pin 9-Chip Parity 70ns FPM Memory SIMMs
But the board will recognize only 512MB of each SIMM for a total of 4MB.
 
chjmartin2 said:
How does this differ from the board I have? Is it simply the 4 mb and 2 mb switch?
Click to expand...

Yes, that's really it and I cleaned up a few traces' routing paths. I also got them with a blue solder mask and added a logo and text. @chjmartin2 The one you have is a prototype design (which miraculously worked on the first revision) but required that jumper mod to make the inboard think that it was 4MB and not 2. The inboard would originally detect the capacity of the piggyback based on a jumped connection, so I added that. I don't see a reason today as to why one would want 2MB when you could just as easily have 4, but the option is now there just because!

And yes, because of the way it is wired, the only option is to use 1mb sticks it you want 4MB. (and because 512K simms weren't made.. I think???)
But 8x256K sticks should work too if you select 2MB.

@saifbadri How did the assembly go?
 
Also, PSA:

Add active cooling with a small fan. I know this older tech can get hot but it will surely not hurt to have some additional active cooling to move air across the chips - especially if you close up the already poorly ventilated PC/XT case case after modding. It will help these old chips last that much longer.

The graphics card I'm using is based on the ATI 18800-1chip and boy does it get hot (and work well with windows @ 1024x768!) I added a stick-on heatsink and have air passing by it.
 
@saifbadri I see you made some stickers from that image post from reddit, too! I searched on google and that appears to be the only image on the internet of this sticker.


.. I did a bit of touch-up in Photoshop to remove the stains. I think my sample of magenta came out a bit too dark. I like the shade you used much better. Here's my touch-up version if you want it!

InBoard_sticker.PNGpublic.jpeg
 
harrison.frazier said:
@saifbadri I see you made some stickers from that image post from reddit, too! I searched on google and that appears to be the only image on the internet of this sticker.


.. I did a bit of touch-up in Photoshop to remove the stains. I think my sample of magenta came out a bit too dark. I like the shade you used much better. Here's my touch-up version if you want it!

View attachment 1266823View attachment 1266824
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Where'd you get that image? I had scanned the sticker off my IBM AT and cleaned it up. I think I posted it around. Just wondering if it's the same image.
 
I image searched and saw the reddit post. Nope not the same one.

I had this as my YouTube picture for years. I'll see if I can dig up my scan, although I may not have it.

Can I buy one of those stickers off you?
 

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