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help finding RAM chips for Heathkit ET-3400 trainer?

R

rebeltaz

Experienced Member
Joined
Nov 9, 2008
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195
Location
Shelby, AL
At a HamFest this weekend I picked up an Atari 800 system with a disk drive and ham radio interface box, a Garmin Ique 3600 GPS/Palm (I know, not technically vintage but obsolete nevertheless) and a Heathkit ET-3400 trainer. The guy had four, but I only bought one - the most complete. The other three were missing ROM chips, keys and a whole host of other necessities.

The only thing that I can tell this trainer is missing (I haven't delved into it that deeply yet) is the two RAM ICs - IC14 and IC15. The manual (which I found online) shows that these are supposed to be 443-721 ICs with 2112-2 as an allowable substitute. They're shown to be 256x4 SRAM chips. I cannot find a datasheet or even pinouts on these chips anywhere. I did happen to write down the numbers on the chips that were in the other trainers there - I figured I could get the chips anywhere. Wrong. Anyway, the chips that were in those units were not the same numbers. Two trainers had 443-764 chips. These come up with the numbers 2114, 4045 and 6614 as acceptable substitutes. These are 1kx4 SRAM ICs. The other trainer there had a TMS2114-45NL IC, which I am assuming is the same as the 2114.

Since I cannot find pinouts on the 2112 and I don't know that much about ancient RAM, I don't know if the 2114 can substitute for the 2112 or not. I think I can find the 2114, but the 2112 seems to be a lost cause, unless someone here might happen to have one (or four) up there sleeve?

Thanks....
 
rebeltaz said:
Since I cannot find pinouts on the 2112 and I don't know that much about ancient RAM, I don't know if the 2114 can substitute for the 2112 or not. I think I can find the 2114, but the 2112 seems to be a lost cause, unless someone here might happen to have one (or four) up there sleeve?
Click to expand...
2114s were used in lots of vintage computers and aren't terribly hard to find. 2112s, on the other hand, I've never come across in the wild. I've picked up NOS 2114s in a local electronics shop very recently. I can see if they have 2112s, but I suspect you can find a more local supplier.

2114s have 18 pins as opposed to the 2112's 16 pins, so a drop-in replacement they aren't. I don't have the pinout at hand either but they are probably similar enough to rig up an adapter with an IC socket or two if you can't find enough 2112s.
 
cosam said:
2114s were used in lots of vintage computers and aren't terribly hard to find. 2112s, on the other hand, I've never come across in the wild. I've picked up NOS 2114s in a local electronics shop very recently. I can see if they have 2112s, but I suspect you can find a more local supplier.

2114s have 18 pins as opposed to the 2112's 16 pins, so a drop-in replacement they aren't. I don't have the pinout at hand either but they are probably similar enough to rig up an adapter with an IC socket or two if you can't find enough 2112s.
Click to expand...

You know... now that you mention the pin count, I was wondering how the other trainers had 2114's in them. I knew there weren't any adapters or anything. I just looked at the trainer I have and, sure enough, the sockets are 18 pin - not 16. Also, unlike the manual that I found, there aren't any sockets for IC16 or IC17 - which would be RAM bank 0001.

Upon further inspection, I realize that the trainer I bought is the 3400A model. I don't suppose anyone has manuals for this?

Thanks...
 
rebeltaz said:
I guess I need a couple of 2114s... they aren't as easy to locate as I had imagined...
Click to expand...

There are a couple on ebay in the 6 to 7 dollar range. The last one sold for close to ten bucks.

No 2112's though.

I will look through my inventory.
 
VintageComputerman said:
There are a couple on ebay in the 6 to 7 dollar range. The last one sold for close to ten bucks.
Click to expand...
Wow, that's steep. You should be able to get them for about $2 or less. I'd send you some myself but shipping would really kill the deal. Have a Google for "2114 ram" or "2114 ram arcade" (they were used in a lot of coin-ops) and you should see a couple of suppliers.
 
cosam said:
Wow, that's steep. You should be able to get them for about $2 or less. I'd send you some myself but shipping would really kill the deal. Have a Google for "2114 ram" or "2114 ram arcade" (they were used in a lot of coin-ops) and you should see a couple of suppliers.
Click to expand...

That was what I thought, too... The local NTE distributor has NTE2114 ICs available, but they want $10 each for them as well. I did do a sarch for "2114 ram" but I didn't really find anything. I'll try again tonight and add "arcade" this time.

---

I must be senile. For the heck of it, I searched for "2114 ram" again and the first freaking link was a supplier. I swear I did search for that and all I got were those websites that have every possible number listed on their site to draw visitors in only to say "item not found".

Anyway.....
 
Last edited:
OK... I finally found some 2114 RAM ICs on eBay at $11 for four (I actually got five!), plugged 'em in... nothing. :( Then I noticed that the freaking CPU was plugged in backwards. I turned it back around and, not expecting it to work, it didn't work. The seven-segment LEDs light up all of their segments and that is it. Pressing RESET doesn't receive the 'CPU*UP' message and no other key has any effect.

I figure that the CPU is fried. Anyone got one of these laying around just taking up space?

Or any other thoughts?
 
Hi
It seems like I'm always advertising for these guys.
Maybe they should give me a cut.
Anyway, Jameco list the 6808 for about 7 or 8 bucks.
Dwight
 
Dwight Elvey said:
Hi
It seems like I'm always advertising for these guys.
Maybe they should give me a cut.
Anyway, Jameco list the 6808 for about 7 or 8 bucks.
Dwight
Click to expand...

Thanks... I'll probably wait until after the next hamfest next month then l'll go that route....

BTW - do you I get a discount if I mention your name? :)
 
Hi Derek,
sorry for replying so late.
If you are still interested: I have several RAM Chips 2112. I can test them and send to you, but I live in Germany....
I also have the pin layout.
All the best

Charly DL4DBY
 
Charly said:
Hi Derek,
sorry for replying so late.
If you are still interested: I have several RAM Chips 2112. I can test them and send to you, but I live in Germany....
I also have the pin layout.
All the best

Charly DL4DBY
Click to expand...

Thanks for the offer, but I found they were 2114s that I needed. Then after buying them, on eBay, I discover the CPU was inserted (by the previous owner) backwards....
 
Dang... I'll have to adjust inventory when I get back in the shop this weekend. I've been out west buying lots of parts for inventory.

I have a few hundred 2114 chips and have plenty in the bins but haven't updated the website inventory yet.
 
2112 data sheets

2112 data sheets

Hi there,

for the past couple of days, I too have been searching for data sheets for the 2112. This evening I located two at The Datasheet Archive:

http://www.datasheetarchive.com/

Search for 2112. In the search results, there are a couple of hits. One is for an Intel part. The other is for a Signetics part.

As well, if you're still looking for a 2112, I have a few of the SY2112A-35 variety. They were manufactured by Synertek and the date code is 8420. So they're about 26 years old now, but still in the package.

Cheers...


... John
 
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