
3/7/88
Rob Horning

I looked at the diode model that they are using with the After Burner
simulations.  I used one of the cross talk test boards to see how the
clamp diode worked and then did a simulation with the same conditions
using the model that they are using with After Burner.  The real board
clamped better than the model.

I have started to work on the schematic and layout for the SRAM arrays and
After Burner.  One thing that I figured out is that we are being very
conservative on After Burner power because only three of the six drivers
will have the maximum load.  (This would go up to four if we use deeper
SRAM's than 16K.)  The proposed pin-out for After Burner will be more
difficult to hook up than the pin-out that I was assuming and so I want to
work on this to make sure that it can be done without adding layers to the
PC board.  they want to freeze the pin-out as soon as possible because of the
long lead times for getting a custom package.

I tried to get pin-outs for the CPU and was told that I could not get them
until at least the end of the month.   Darius does not think it is a high
priority to get us pin-outs because he does not think that we will have CMUX
chips before the first part of next year.  We may want to re-evaluate our
mile stones based on when we will get CMUX and CPU chips.

I looked at using the 25 mil pitch SRAM package.  I talked to some people
about PC board technology and there is a chance that we could us a 25 mil
part.  It turns out that it is actually a 21 mil part.  I am not sure how
much more difficult this makes things.

I distributed the results of the work that I did with the Hitachi SRAM's.
Forsyth is concerned about the the delay for the data cache tag lines.  We
may want to try to get Hitachi to change there output driver so that it drives
heavier loads better.  If we do this we will have to let all the vendors know
about this requirement.
