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

Johnny Billquist bqt at update.uu.se
Fri Mar 20 06:32:03 CDT 2015

On 2015-03-20 07:21, emanuel stiebler wrote:
> On 2015-03-19 17:13, Johnny Billquist wrote:
>> On 2015-03-19 17:02, Noel Chiappa wrote:
>>>      > From: Mark Kahrs
>>>      > 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 ...
>>>      > (n.b. there is a 4Mx8 but it's only in BGA, so fuggitaboutit).
>>> Actually, one 4Mx8 (assuming it's really only 8 bits wide) wouldn't
>>> be as
>>> easy to work with as two 2Mx8; since most QBUS cycles are 16-bit word,
>>> not
>>> byte, you'd have to do two memory cycles for each QBUS cycle -> more
>>> complexity.
>> And for the 11/70, we're talking about 32-bit wide memory...
> Just because nobody mentioned it so far, what about the cy7c1460?
> 1mx36, so you even get the parity if you like one.
> Used them quite a lot, are nice chips, and speedy too.

Sounds like a perfect fit for the 11/70. One chip, and you're done. :-)


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