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Re: 747 Rom Emulator / design




On Thu, 27 Jul 2000, rr wrote:

> 
> Dual port ram is really not required. It's expensive and can be
> tough to get. Remember that the ecm's bus cycle time is almost
> a usec. Some 100 to 150 nsec SRAM can easily be updated
> within a part of the cycle.

But isolating the RAM from the ecm bus and from the PIC bus takes a
bunch of 20 pin chips.  This is why I bought a Xilinx development system
(It was delivered today; can hardly wait to get home!).

> 
> Another way to look at it is: Does it matter if the ecm goes into
> limp when your updating the ram, you can't be driving at
> the same time your punching keys on a laptop.
> 
> BobR.

There are _other_ things I want to do, besides an eprom emulator :-)

- Steven Ciciora

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