4 MB memory unibus/qbus card (was Qbus split I&D?)

Paul Koning paulkoning at comcast.net
Thu Mar 19 09:29:03 CDT 2015

> On Mar 19, 2015, at 8:09 AM, Mark Kahrs <mark.kahrs at gmail.com> wrote:
> This is a classic case of "Great minds run in the same ruts" (sometimes
> rephrased as gutters...)
> I've almost designed a 4 MB card twice now.  Because I'm a cheapskate, I
> didn't want to use FRAM.  And there are very nice SRAMs available: for
> example, the Cypress CY62167 is a 2Mx8 1Mx16 RAM in 48 pin TSOP.  So you'd
> need two, that's ~$30 total. (n.b. there is a 4Mx8 but it's only in BGA, so
> fuggitaboutit).

I used to think of BGA as not possible for home construction.  Then I read a nice article — https://www.beta-estore.com/download/rk/RK-10001_76.pdf — about reflow soldering using what amounts to a toaster-oven with a temperature control added, which apparently does the job just fine.  There are some details to get right, which the article explains.


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