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Datasheet for National Semiconductor MM5262N RAM

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GearTechWolf

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These oddball 22-pin DIPs of middle-size width (3/8" x 1-1/8") is part of a collection of components my father bought in his you with the intention of building his own computer. (from a bunch of TO-100 components, maybe shift-registers? Plus these ram chips)
Fortunately, there were almost enough matching sockets to put all of them in sockets. But I can't do much with them without a pin-out and size/speed information.
I've been looking here but finding nothing: http://www.bitsavers.org/components/national/_dataBooks/
Anybody got a lead on info?
 
Standard DRAM for the early-mid 70s. 3 rail supply voltages, slow (ca. 500 nsec) access times, and a bit power hungry (1W). The 4K ones like the 2107 were more common. I believe that the MITS 4K DRAM boards used those.
 
Thanks for the context! Always nice to have additional data on vintage parts.
Maybe I can find a use for them in some similar-era project now that FishFinger found the datasheet.
Interestingly, the datasheet mentions them being intended as a replacement for Core Memory, so that's neat!
 
Yup, that was their primary market--replacement for core. It was a big deal when mainframes started coming out with semiconductor memory. FWIW, it wasn't any faster than core originally, but easier to implement. Error correction was almost a requirement back then because ceramic packages that were used for DRAM would emit the occasional alpha particle and cause a bit error. Since this didn't happen consistently, such errors were categorized as soft errors. I think I still have a bunch of 4K 22-pin Fujitsu chips squirreled away somewhere.
 
GearTechWolf said:
Alpha-particles from the ceramics? That's wild! I wonder why?
Click to expand...

Semiconductor package ceramics contain a lot of metallic elements (aluminum oxide, mostly) because they are good at shielding the chip from outside interference. But those materials are themselves prone to being contaminated with small quantities of radioactive isotopes; bismuth, polonium, thorium, and uranium are all common enough to cause the occasional mischief.
 
Huh, Fascinating! I guess that's part of the reason for the later shift to plastics, plus lower costs of course.
 
I believe that commercial-grade logic is still cerDIP packaged (e.g. SN5400 logic). Heat dissipation is much better than plastic. All of my ECL chips are so packaged.
 
Commercial being what is used by manufacturing companies and such, or?
Consumer-grade stuff certainly rarely bothers with better than plastics, it seems.
 
Commercial my term for "military/aerospace grade". E.g. SN54xxx instead of SN74xx. Perhaps I should have been more explicit. Some products were packaged as cerDIP because of their heat dissipation; for example, the 8087 NDP.
 
Ah, I see! I think I may have a few 54-series chips in plastic packaging, but there are always excepts to the rule/standard.
Perhaps some variety of less-sensitive logic or a slightly down-scaled version for non-military use once it became widely available.
 
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