NatSemi QBUS 256KB memory card

Noel Chiappa jnc at
Tue Dec 16 10:28:12 CST 2014

So there is a National Semiconfuctor 256KB QBUS memory card which has a
number of examples floating around for sale (e.g. eBay #370953707487), but
which has heretofore been un-identified: the only numbers/names/etc on it are
"PWB 551103882" and "PWA 980103882", which is what one usually finds them
listed under.

Well, it turns out that it's called an "NS23M", and a manual and print set
for it, previously un-available online, are now available here:

Can people who maintain repositories (e.g. BitSavers) please include this in
their sites?

Sorry about the size of the file; the original scans were 300 dpi, which in
retrospect was probably a bit more than needed, but rather than throw away
resolution, I've left them in like that; repository maintainers may wish to
reduce the page images in resolution somewhat, to make the file a bit smaller.

And a very big 'Thank You' to Mr. Steve Burgess, who was nice enough to make
scans of a manual in his possession, and send them to me. If anyone finds this
manual useful, please make a small donation to a local animal charity!


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