Re: [N8VEM-S100:977] i960 / V96BMC ~BLAST timing

[mike <mi...@pikeaero.com>]

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John,

The burst-mode simply means that the processor is requesting a small
number (usually about 4) memory transactions back-to-back, one on each
clock cycle, without having to start from the beginning of initiating
a transaction each time.

The processor will assert the ~BLAST (Last cycle of the burst) line on
the last cycle of the burst.

I believe the DX486 was the first in the Intel family that used burst
mode. I believe that if you look at the DX486 pinout you will find a
~BLAST pin.

This is why, when using the burst-mode controller with the 386 you
would need to have ~BLAST asserted on the first cycle of the memory
transaction to indicate that it is both the first and the last
transfer cycle in the transaction (in other words an ordinary memory
transfer).

Regarding the 64MB upper limit of the V96BMC, I was trying to sort
that out also. Their literature claims the capability to drive
512MBytes of DRAM.

Are you accounting for all the rows and columns?

In any case, yes, I was tearing my hair out late at night trying to
sort that out, it was giving me a headache. I'll try again with a
clear head.

- --Mike

On 07/16/2012 01:51 PM, John Monahan wrote:
> The later/higher capacity Controller chips all seem to call bro
> Burst mode refresh.  Unfortunately I don?t understand this area
> enough to know if that can be used with an 80386.


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