the "Jonas Sound Card"
      an interresting "alternative" to the Mockingboard		    Page No.:H213-3
 
         
     
 		  
   

As explained in the previous page the first revision of the card has occasionaly problems with the handling of the databus between the WD65C22 and the
  soundchips YM-2203 and YMZ-284. This problem is solved in the second revision. See the circuitplan of the second revison below and put your attention to
  the CS-lines ( CS=Chip Select ) and the driving of that lines in the circuitplan below:
 

   

 At the second revision also the area of components related to the IIGS soundport was set apart from the audiopart related to the audio-preamps of the 
 soundchips and it turned out if another kind of coolingsink would be used at the poweramp chip the space can be optimized and it also turned out to be
 better, if at least the connectors for the speakers could be set inwards at the card giving more space between connector and rearplate of the IIGS for
 rectangled plugs.

 The new layout of the card resulted to this design:
 

   

 and the completed card looks like this:
 

   

 But even this second version canīt be the final solution, because it does not unleash the total abilities of the card. Up to the moment it only supports
 4 abilities:
    1. emulating the Mockingboard A
    2. using the additional modes of the YMZ-284 ad its DA capabilities
    3. using the additional modes of the serial DA of the YM-3014
    4. amplifying the sound taken from the IIGS soundport
 But the "ideal" solution would be the ability to "add" or "mix" any of this 4 sources in any combination.
 This would give the contol of a very advanced soundsystem to the user with at least a dozend of different soundsources per channel:
       rectangular wave generators,
       sinewave generators and
       noise generators
 and not to forget the ability to use also the FM-abilities.

 But such a "final revision" would demand major changes to the previous designs:

     A) the "switching modes" must be expanded to 8 or 16 switchmodes per channel
          and they must get syncronized  with the related Chipselect lines of the selected devices -
          that demands change from 4052 analog switches ( 2 x 4 in to 1 out ) to 4051 analog switch ( 1 x 8 In to 1 out )
     B) the databuses must get latched so that after one source has been set and programmed it must keep this setting till it is released while during
          "hold-time" the next sources might be set by their latches..... and that latches must be syncronized with the related databus latches.
     C) not a demand but a wish, would be the ability to set the amplitude ( loudness ) by digital potentionmeter and software instead of using hardware
           trimmers in such a case its probably a good idea for saving additional space by not keeping the connectors to the peripherial speakers and LineOut
           "on the board" - but instead using a row of pinconnectors and using an external aluminium "connector-plate" that can be mounted to the rear plate
           of the Apple.
 and there is only limited amount of additional space availiable to the card - in "worst case" this might require the use of a PAL aiming to reduce the amount
 of logic chips at the board.

 The next level of revision is at the next page:

 
         
         
         
         
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