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Does a DRAM cross reference exist?

R

RDuckey

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Jan 27, 2021
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During my short time playing with 30-40 year old machines, I keep running into different DRAM chips that may be the same as others, but it is sometimes difficult to find data sheets on some of these. My most recent example is a Quadram Quadboard ram expansion board that I picked up from eBay. The board came full of Motorola MCM6665BP-20 16 pin chips. I have driven myself and Duck-Duck-Go slightly nuts trying to find a data sheet for them. I did succeed in finding MCM6665A, which has the same pinout as a HM4716A.

After I repair the slight damage caused by the "VARTA - most hated brand of battery ever", I want to test the chips prior to sticking the board in my working XT. It would be nice if someone had a cross reference that said that "this" chip is the same as "that" one.

Is there a list hidden somewhere that would be helpful?
 
RDuckey said:
After I repair the slight damage caused by the "VARTA - most hated brand of battery ever"
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That is unfair criticism. Those batteries are WAY past their use-by date. I don't criticise Ford for 30 year old cars where some components, e.g. rubber seals, battery, gadgets, etc. did not survive 30 years.

RDuckey said:
It would be nice if someone had a cross reference that said that "this" chip is the same as "that" one.
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For DRAM chips typically found in IBM PC family computers and cards, there are lists at [here] which can assist in finding a compatible chip.
For example, the MCM6665BP20 appears in the '4164 class' list.
 
Thank you, once again. I obviously need to spend more time on your website. I truly have missed a lot of pages.
modem7 said:
That is unfair criticism.
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Fair or not, when another motherboard is destroyed by a hard to remove battery, no one that I have met personally, has said Varta in anything but a very derisive way. The above is a quote from a relatively popular retro computer Youtuber.

When the battery dies in my 1947 Ford 8N tractor, it doesn't destroy the engine.
 
modem7 said:
Although, you could start that tractor, the deteriorated timing belt breaks, and that could destroy the engine.
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A ‘47 Ford is a side-valve flathead with replaceable cylinder liners. Short of having the Iron Giant bite it completely in half there’s nothing you can do to destroy that engine.
 
RDuckey said:
When the battery dies in my 1947 Ford 8N tractor, it doesn't destroy the engine.
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Sure, but I’ve seen more than one old car with the battery tray completely corroded away because the lead acid battery leaked. If the wiring harness is in the blast zone it’s a pretty analogous situation.
 
RDuckey said:
When the battery dies in my 1947 Ford 8N tractor, it doesn't destroy the engine.
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modem7 said:
Although, you could start that tractor, the deteriorated timing belt breaks, and that could destroy the engine.
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Eudimorphodon said:
A ‘47 Ford is a side-valve flathead with replaceable cylinder liners. Short of having the Iron Giant bite it completely in half there’s nothing you can do to destroy that engine.
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I knew that I shouldn't have gone outside of my areas of expertise. The closest that I have come to a tractor, is the tractor feed on my old dot matrix printer.
 
modem7 said:
I knew that I shouldn't have gone outside of my areas of expertise. The closest that I have come to a tractor, is the tractor feed on my old dot matrix printer.
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A "friend" decided to take my tractor for a drive... It's been dead now for a decade.
It's not even the fact that he damaged the engine that killed it. He took it home to fix it up...
Now I have no idea where the engine is... And I have a tractor slowly rusting away because the engine is unlikely to ever be found again, let alone fixed....
I'll take a Varta battery over this friend any day. At least the motherboard doesn't disintergrate into nothing when they leak.
 
Wet liners are fun *Not*, I haven't done any wet liner work for probably 40+ years and haven't driven a tractor for probably the same amount of time.
 
modem7 said:
I knew that I shouldn't have gone outside of my areas of expertise. The closest that I have come to a tractor, is the tractor feed on my old dot matrix printer.
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And I should have known better than to inject joviality into an Forum that is, generally, very serious about the topics being discussed and with people with different views that I will never have the distinct honor of meeting. My poor sense of humor fails me continuously. My apologies. Once again.

seat safety switch said:
I've also used the PCBJunkie page on RAM cross reference: http://pcbjunkie.net/index.php/resources/ram-info-and-cross-reference-page/
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Thank you. I will look into that page as well as modem7's provided links.

I wonder if the dashes in between the words of the page title affect the ability of my search engine to find the results. Does a search engine see "ram-info" as one word or two?
 
I reviewed my search history and found that I had searched for DRAM not RAM. Therefore the apothecary and shotgun loading references returned seemed, at the time, a little odd, but were actually what I had asked for.
 
Malc said:
Wet liners are fun *Not*, I haven't done any wet liner work for probably 40+ years and haven't driven a tractor for probably the same amount of time.
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I think the Ford uses dry liners, but I'll admit it's not really my area of expertise. The only flathead engines I've ever had the pleasure of actually owning were in lawnmowers.

RDuckey said:
And I should have known better than to inject joviality into an Forum that is, generally, very serious about the topics being discussed and with people with different views that I will never have the distinct honor of meeting. My poor sense of humor fails me continuously. My apologies. Once again.
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I'm not sure what the deal is with the wounded tone, here. I'd say people responded with reasonably good humor; you inserted an absurd analog to the leaky battery situation and people tongue-in-cheek riffed on its level of accuracy. Seems par for the course.
 
Malc said:
Wet liners are fun *Not*
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I don't understand. How is incontinence underwear relevant to the conversation? :)


RDuckey said:
I obviously need to spend more time on your website. I truly have missed a lot of pages.
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Some pages are 'buried' quite deep behind the parent page. You would have to navigate through the entire site, which could take a while. And some pages are orphans, which I point to on an as-required basis.

I have though, started to create an index for some 'buried/orphan' pages. A link to the index is at the bottom of the parent page.
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