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

[Mark Kahrs]

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).

So, you'd only need the bus interface (no, I'm not going there) and the
control logic.

These SRAM parts are so speedy (45 ns) that cache isn't needed (obviously).

Maybe I'll almost design it for the third time!