Were to buy 2114L ram??

[The Soulman]

I have a old Keithley 192 digital multimeter with faulty 2114 rams, main cpu is 6808 with 6522.
Thirty years ago I would have gone to the computer/electronics store around the corner..
Were to buy 2114l ram in 2020? (outside dodgy ali-e and ebay offerings?)

[jfiresto]

The Silicon-Ark has new old stock 2114s for 4 pounds each.

[The Soulman]

Thanks, will probably order next week if nothing else comes up. 

[granzeier]

https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=38973&CID=EPIPRODUCTLINK - $2.95 ea (2.72 Euro) - I don't know about shipping to you.

This is for the 2114N, which is supposed to be a low-power version. The 2114A should be drawing 370 mW, but I cannot find a good power rating for the N. Either way, since the full-strength 2114A is supposed to draw ~500mW, the worst that should happen is that your battery will drain a tiny bit faster.

EDITED - I just looked it up, and it runs on mains power. So the only trouble might be that it will run a tiny bit hotter (but probably not enough to notice.)

[The Soulman]

Thanks for tip but shipping makes it costly, $18 and above..
Will see if they have anything else I may need.

Although I do want to minimize the power consumption and heat, a couple hundred mili Watts wouldn't be a deal breaker.

[granzeier]

OUCH! That is pretty high.

I believe that it only costs me about $5-$6 to send a small packet pretty much anywhere in the world (via U.S. Postal Service.)

PM me your address, and on Monday I will get a quote on shipping a package to you. Also, send how many your meter need, and I will see what I have.

[Alex Eisenhut]

Well if you have the space you can whack in almost any kind of SRAM chip, just tie the unused pins. Cache SRAM chips from 486-era motherboards come in 28 pin DIP packages and have like 128kx8bits.
Then again I got all mine when people were throwing these out by the truckful and I didn't pay much for them...

[granzeier]

Well if you have the space you can whack in almost any kind of SRAM chip, just tie the unused pins. ...

Theoretically that would work; the trouble is that it would be wildly impractical. The 2114 is only 4 bits wide, and so you would have to create a daughter board with pins which perfectly line up with both of the 2114 chips, and then run the address, power and control lines to both chips, while running half of the data lines to each chip separately. That also assumes that there is, as you mentioned, enough room inside the meter's case for the additional board, and the new RAM chip.

[Alex Eisenhut]

Well if you have the space you can whack in almost any kind of SRAM chip, just tie the unused pins. ...

Theoretically that would work; the trouble is that it would be wildly impractical. The 2114 is only 4 bits wide, and so you would have to create a daughter board with pins which perfectly line up with both of the 2114 chips, and then run the address, power and control lines to both chips, while running half of the data lines to each chip separately. That also assumes that there is, as you mentioned, enough room inside the meter's case for the additional board, and the new RAM chip.

You mean "perfectly practical", you just described the task, it's hardly nuclear fusion. And given the pricing of PCBs, it would end up cheaper than a NOS 2114.

[Syntax Error]

FYI the original ZX81 was populated with a pair of 2114's as 1K x 4bit. Sometimes a single 4118 as 1K x 8bit depending on availability. I understand the Vic20 also used lots of 2114L's Thus it may be cheaper to rip some junk retro kit from ebay than go for pre-ripped antiques.

Vic20 Ram schematic https://www.commodore.ca/manuals/funet/cbm/schematics/computers/vic20/251027l3.gif

[granzeier]

You mean "perfectly practical", you just described the task, it's hardly nuclear fusion. And given the pricing of PCBs, it would end up cheaper than a NOS 2114.

Ok, I guess that you must have more experience at PCB design than I do. It's just that in my experience (with over 100 boards): it is not too difficult to design a PCB to do this, but to get the measurements of the two 2114s perfect is the killer. And, being cheaper than the 2114s would demand that you get the measurements perfect on the first try.

Go ahead and offer to design the board for Soulman; I'm sure that he will appreciate it.

[The Soulman]

Well if you have the space you can whack in almost any kind of SRAM chip, just tie the unused pins. ...

Theoretically that would work; the trouble is that it would be wildly impractical. The 2114 is only 4 bits wide, and so you would have to create a daughter board with pins which perfectly line up with both of the 2114 chips, and then run the address, power and control lines to both chips, while running half of the data lines to each chip separately. That also assumes that there is, as you mentioned, enough room inside the meter's case for the additional board, and the new RAM chip.

You mean "perfectly practical", you just described the task, it's hardly nuclear fusion. And given the pricing of PCBs, it would end up cheaper than a NOS 2114.

Yeah, but why design it when you can buy it for 4 dollars on ebay? 

[The Soulman]

OUCH! That is pretty high.

I believe that it only costs me about $5-$6 to send a small packet pretty much anywhere in the world (via U.S. Postal Service.)

PM me your address, and on Monday I will get a quote on shipping a package to you. Also, send how many your meter need, and I will see what I have.

That is very kind of you, needs two, will send pm.

[edavid]

I believe that it only costs me about $5-$6 to send a small packet pretty much anywhere in the world (via U.S. Postal Service.)

You are mistaken.  Minimum retail cost for a USPS package sent to the Netherlands is $14.50.

If you sign up for a pirateship.com account you can use their "Simple Export Rate" of $10.95, but I haven't found any cheaper option.

OP should just order those dodgy parts from eBay or AliExpress - I have not had much trouble with them.

[edavid]

Theoretically that would work; the trouble is that it would be wildly impractical. The 2114 is only 4 bits wide, and so you would have to create a daughter board with pins which perfectly line up with both of the 2114 chips, and then run the address, power and control lines to both chips, while running half of the data lines to each chip separately. That also assumes that there is, as you mentioned, enough room inside the meter's case for the additional board, and the new RAM chip.

Instead of worrying about spacing, just use an 8 bit RAM to replace each 2114 

[jfiresto]

You are mistaken.  Minimum retail cost for a USPS package sent to the Netherlands is $14.50.

Would that be by uninsured First Class International? Insurance would add another $16 minimum. 

[edavid]

You are mistaken.  Minimum retail cost for a USPS package sent to the Netherlands is $14.50.

Would that be by uninsured First Class International? Insurance would add another $16 minimum. 

You can get third party insurance for $1.35.

[The Soulman]

Theoretically that would work; the trouble is that it would be wildly impractical. The 2114 is only 4 bits wide, and so you would have to create a daughter board with pins which perfectly line up with both of the 2114 chips, and then run the address, power and control lines to both chips, while running half of the data lines to each chip separately. That also assumes that there is, as you mentioned, enough room inside the meter's case for the additional board, and the new RAM chip.

Instead of worrying about spacing, just use an 8 bit RAM to replace each 2114 

I haven't decided either way,

First, I'd probably replace the faulty rams with used but known working direct replacements to make sure that was the fault and see if the 100 point data-logging is then working reliable.

Secondly, how long will 30 year old, used ram chips last?
Doing a mod to more modern chips might be worth the hassle in the end, so any suggestions for those is much appreciated.
Or is it a good time to learn arduino and use that?

I'm not to worried about hacking some hardware together, but haven't done any digital designs and programming apart
from turbo pascal and some basic shift registers etc. over twenty years ago..  time flies when you're getting old(-er).
So any tips and pointers there are also much appreciated.

[jfiresto]

You are mistaken.  Minimum retail cost for a USPS package sent to the Netherlands is $14.50.

Would that be by uninsured First Class International? Insurance would add another $16 minimum. 

You can get third party insurance for $1.35.

Oh, dear. That actually makes sense in a twisted sort of way.

[The Soulman]

You are mistaken.  Minimum retail cost for a USPS package sent to the Netherlands is $14.50.

Would that be by uninsured First Class International? Insurance would add another $16 minimum. 

You can get third party insurance for $1.35.

Insurance isn't mandatory, is it?

[edavid]

Secondly, how long will 30 year old, used ram chips last?

Probably for the life of the meter.

I suppose if you are worried you could try 5114s... they might last longer on the basis of lower power -> less heat.

BTW, how did you decide that the existing 2114s are bad?

[edavid]

Did you see this eBay listing?

eBay auction: #323778016598

[The Soulman]

Secondly, how long will 30 year old, used ram chips last?

Probably for the life of the meter.

I suppose if you are worried you could try 5114s... they might last longer on the basis of lower power -> less heat.

BTW, how did you decide that the existing 2114s are bad?

Good question, just a hunch really, apart from the 100 point data logging and the self-test mode everything else digital on the meter works just fine.
The data logging works as intended except for reading back data points, sometimes there is no data, sometimes a little data, sometimes garbage data.
Also from what I understand is the self test uses the ram.
Yes it could also be that the uc garbles up the writes, but all other logic ic's driven from it are functioning fine,
why would only the memory lines fail?

My idea was to get some chips put them in and go from there.

[The Soulman]

Did you see this eBay listing?

eBay auction: #323778016598

Nope, thanks. 

[granzeier]

Soulman,
Did you ever order those chips from E-Bay?