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Note 19.0                 Disabling RAM on the MXV11-BF               No replies
JAWS::KAISER                                        132 lines  25-MAR-1985 09:24
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      +---------------+					   +-----------------+
      | d i g i t a l |					   |  uNOTE # 019    |
      +---------------+					   +-----------------+


      +----------------------------------------------------+-----------------+
      | Title: Disabling RAM on the MXV11-BF		   | Date: 10-JAN-85 |
      +----------------------------------------------------+-----------------+
      | Originator: Mike Collins			   | Page 1 of 3     |
      +----------------------------------------------------+-----------------+


      This uNOTE describes how to disable the on-board memory of the  MXV11-BF
      multifunction  module.   There  is also a comparison of features between
      the MXV11-BF (with RAM disabled) and the combination of the MRV11-D  and
      DLV11-J modules.

      DISABLING RAM ON THE MXV11-BF MODULE



				      WARNING!

	  The procedure outlined below	for  disabling	the  RAM  requires
	  physical changes to the circuit board.  Implementing this change
	  will void the warranty of the MXV11-BF as well  as  voiding  any
	  field service contract for the board.


      The procedure requires cutting one etch and adding one wire.

      PROCEDURE (see figure below)

	   1. The etch cut can be achieved two ways.

	      Cut and bend up pin 13 of chip E17.

			   OR

	      On side 2 of module (the non-component side), cut etch
	      which connects E17 pin 13 to E26 pin 2.

	   2. Add wire between E17 pin 13 and E17 pin 14 (+5 Volts).

	   3. The on-board RAM is now disabled.
									Page 2


				MXV11-BF (M7195)


	       |						   |
	       |						   |
	       |						   |
	       |			       Pin 1		   |
	       |			       |		   |
	       |			       | Pin 14		   |
	       |			       | |		   |
	       |			       | |		   |
	       |			       | |		   |
	       |			   +-+ V V     +-+	   |
	       |	    Pin 1 ---> +-+ | | +-+ +-+ | | +-+ +-+ |
	       |		       | | | | | | | | | | | | | | |
	       |	    E26 -----> | | | | | | | | | | | | | | |
	       |		       | | | | | | | | | | | | | | |
	       |		       +-+ | | +-+ +-+ | | | | | | |
	       |			   +-+	^      +-+ | | | | |
	       |				|	   +-+ +-+ |
	       +-+			  +-+	|		   |
		 |		      +---+ |	|		 +-+
		 |		      |	    |  E17		 |
		 |		      |	    |			 |
		 +--------------------+	    +--------------------+


      COMPARISON OF THE MXV11-BF VERSUS THE COMBINATION OF MRV11-D AND DLV11-J

      The following table lists several features common to both	 the  MXV11-BF
      with the RAM disabled and the MRV11-D / DLV11-J combination.

      FEATURE	      MXV11-BF w/o RAM	      MRV11-D and DLV11-J

      RAM	      None		      None

      Boot ROMs	      MXV11-B2		      MXV11-B2

      SLU's	      2 DLARTs		      4 UARTs
		      4 baud rates	      9 baud rates
		      No format options	      Many format options
		      (Start, stop bits, parity, # of bits, etc.)

      Miscellaneous   4 Red LED's	      14 unused ROM/RAM sockets
      features	      1 Green LED

      Cabinet kit     Currently N/A	      Available

      +5 V	      3.4A		      2.6A

      Heat diss.      16.65W		      16W
									Page 3


      FEATURE	      MXV11-BF w/o RAM	      MRV11-D and DLV11-J

      Slots	      1 dual		      2 duals

      AC loads	      2.3		      4.0

      DC loads	      0.5		      1.5

      +12 V	      0.1A		      0.25A

      When comparing the features on page 2, the  MRV11-D/DLV11-J  combination
      works  out better than the MXV11-BF.  All of the features on page 3 show
      the advantages of the MXV11-BF.

      The MXV11-BF is the best choice in situations where backplane space  and
      loading  is  a  primary  concern.	  In  terms of backplane space, if the
      number of slots available is limited, the MXV11-BF is  preferable	 since
      it  takes	 up  one  dual	slot  whereas  the MRV11-D/DLV11-J combination
      requires two dual slots.

      In a large system where AC loading may be a concern, the	MXV11-BF  also
      has an advantage over the MRV11-D/DLV11-J combination.  The number of AC
      loads the MXV11-BF presents to the bus  is  fewer	 than  the  two	 board
      combination.

      The most attractive use for the MXV11-BF is in a	minimal	 yet  powerful
      two-board system i.e.  KDJ11-A and the MXV11-BF.	The advantages of such
      a system are the size or form factor  (only  two	dual  height  modules)
      128Kb  of	 RAM,  2  serial  lines,  bootstrap  capability	 and  the high
      performance 11/73 CPU.