From: <noreply_at_sourceforge.net>
Date: Sat, 22 Jun 2002 03:04:06 -0700

Feature Requests item #572446, was opened at 2002-06-22 03:04
You can respond by visiting:
http://sourceforge.net/tracker/?func=detail&atid=439121&aid=572446&group_id=44306

Category: None
Group: None
Status: Open
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: More DRAM 8MB !!- look possible

Initial Comment:
It turns out SH-1 can support 4Mx16 4K refresh DRAM
directly. No need for address mux as I have
indicated...

4Mx16 DRAM 4K refresh
Row address: A0-A11
Col address: A0-A8

when mapped to the SH-1 multiplex address

Row address = A10-A21
Col address = A0-A9

As you can see all the address bits are there and there
are no overlapping, so the entire DRAM can be
addressed.

Minor bit of bad news:
It turns out the pinout is slightly different due to
the use of the TSOP50 package. A few of the pins are
shifted. Shouldn't be a big deal IF (big if and only
if) you can already replace a 0.8mm pitch device
perfectly - to bend a few pins up and solder a few
additional jumpers.

The refresh register have to be programmed to provide
the refresh intervals, but that's do-able.

Suitable parts seems to be (haven't tried it):
Samsung: K4E641612E
Micron: MT4LC4M16R6

Do not use 8K refresh versions as it won't work.


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Received on 2002-06-22