Interfacing a 68000 to RAM
Holger Veit
holger.veit at iais.fraunhofer.de
Mon Jun 1 10:52:46 CDT 2009
dwight elvey schrieb:
> Hi
> Does anyone have a nice pointer to a diagram
> of how the 68K bus is to be connected to RAM?
> I not that familiar with all the various signals.
> I've spent some time searching but maybe don't
> have the right search string.
> Dwight
Google search string may be "68000 schematics", and it will point to the
first link
of "68k Single Board Comupter" from "....ac.th" which hides the
interesting part
in a CPLD, but the second link will lead to a detailed PDF
http://www.chiark.greenend.org.uk/~theom/electronics/has/ha68ksys.pdf
which describes the stuff.
Basically, you can derive the relation of UDS, LDS, R/W, AS and DTACK
from the
data sheet, for interfacing RAM the trick part is just the generation of
DTACK;
as long as CPU clock and RAM access time is known, it is a straight forward
wait state circuit.
--
Holger
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