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Richard Erlacher
09/26/12 15:51
Read: 782 times
Denver, Co

#188465 - It's a bit tricky synchronizing an 805x with 68k series
Responding to: ???'s previous message
A lot depends on which68K CPU you're using. The reason is that, depending on whic 68K CPU you have, the bus cycles are quite regular and symmetrical with some while not so much with others (particularly the later ones). It's been suggested that we might be more helpful if we could look at the arbitration logic and system timing. The 68K has a signal that can be used to synchronize its operation with that of another processor, in this case the 805x, which has no such signal.

I worked with 68K CPU's when they (and the 805x) were new. I haven't fiddled with 'em since the 68030 and beyond became popular. We did all sorts of tricky things back then, including operating pairs of 'em on opposite phases of the clock, using the same shared memory, which is not so easily achieved with Intel processors.

It would be interesting to see how the 805x's ALE and the 68K's DTACK signals are used.


List of 18 messages in thread
SRAM issues      Harry Leung      09/26/12 04:09      
   Setup and hold times?      Per Westermark      09/26/12 04:21      
      RAM issues      Harry Leung      09/26/12 06:13      
         Or narrow pulses ?      Jim Granville      09/26/12 19:46      
      Address setup time      Harry Leung      10/02/12 20:48      
   did you change the arbitration?      Erik Malund      09/26/12 07:18      
      Ram issues      Harry Leung      09/26/12 07:36      
   P0, P2 for memory only, or ...      Erik Malund      09/26/12 09:04      
      p0 and p2      Harry Leung      09/27/12 03:29      
         If you latch both P0 and P2, there will be stabile A15-A0      Richard Erlacher      09/27/12 11:24      
   Arbitration circuit      Oliver Sedlacek      09/26/12 10:08      
   It's a bit tricky synchronizing an 805x with 68k series      Richard Erlacher      09/26/12 15:51      
   you are using a latch, and not a flipflop, right?      Richard Erlacher      09/26/12 22:54      
      FF or latch      Harry Leung      09/27/12 03:30      
         It's a mistake I've seen a time or two ...       Richard Erlacher      09/27/12 11:19      
            time wasting      Stefan KAnev      09/27/12 13:24      
               no circuit diagram      Harry Leung      09/27/12 20:38      
                  You don't have to do that      Richard Erlacher      10/05/12 13:45      

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