[Coco] MPI writing to $c000

[RETRO Innovations]

On 1/24/2016 7:04 AM, Darren A wrote:
> On Sat, Jan 23, 2016 at 11:27 PM, RETRO Innovations wrote:
>
>
> Does your RAM also have a CE* input? If so, how is it connected? The SRAMs
> I have used have CE*, OE* and WE*.  For a write both CE* and WE* must go
> low and OE* is a "don't care".
CE is grounded.
>
> I think the correct equation for a write cycle would be:
> RAM_xE = !(E & !R_W & A15 & A14 & !A13)  ; go low if E is high and Write is
> low and A15 is high and A14 is high and A13 is low
>
> That would have the RAM latch the address on the rising edge of E, and
> latch data on the falling edge.
>
> For a fast RAM you could limit it to just the latter half of E high by
> adding !Q to the mix:
> RAM_xE = !(E & !Q & !R_W & A15 & A14 & !A13)  ; go low if E is high and Q
> is low and Write is low and A15 is high and A14 is high and A13 is low
Hmm, looks like I tried both of those.  No go.  I can try both on the 
unit without the MPI to make sure they work without it.