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Note 20.0                    MXV11-A, -B Differences                  No replies
JAWS::KAISER                                         84 lines  25-MAR-1985 09:24
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      +---------------+					   +-----------------+
      | d i g i t a l |					   |  uNOTE # 020    |
      +---------------+					   +-----------------+


      +----------------------------------------------------+-----------------+
      | Title: Differences between the MXV11-A and MXV11-B | Date: 10-JAN-85 |
      +----------------------------------------------------+-----------------+
      | Originator: Dave Smith				   | Page 1 of 2     |
      +----------------------------------------------------+-----------------+


      This MicroNote illustrates the features to consider when upgrading  from
      MXV11-AA/-AC  to MXV11-BF multifunction boards or when choosing one in a
      new configuration.

      +-----------------------------------+----------------------------------+
      |					  |				     |
      |		MXV11-A			  |		MXV11-BF	     |
      |					  |				     |
      +-----------------------------------+----------------------------------+
      |					  |				     |
      | o Dual height form factor	  | o Dual height form factor	     |
      |					  |				     |
      | o 18-bit compatible only	  | o 18 or 22-bit compatible	     |
      |					  |				     |
      | o 2 SLU's (DLV11-J type)	  | o 2 SLU's (DLARTs)		     |
      |					  |				     |
      | o RAM:				  | o RAM:			     |
      |	   8 KB non-parity (MXV11-AA)	  |    128 KB non-parity	     |
      |	   32 KB non-parity (MXV11-AC)	  |				     |
      |					  |				     |
      | o ROM: 2 sockets (24-pin)	  | o ROM: 2 sockets (28-pin)	     |
      |	   (for MXV11-A2 boot ROMS	  |    (for MXV11-B2 boot ROMS	     |
      |	   - cannot use MXV11-B2 ROMS)	  |	- cannot use MXV11-A2 ROMS)  |
      |					  |				     |
      +-----------------------------------+----------------------------------+


      Notes:

      The MXV11-B2 Boot ROMs are required for an LSI-11/73 based system to  be
      maintained under a DEC Field Service contract because these ROMs contain
      cache diagnostics.

      For a comprehensive list of Bootstraps  and  device  support,  refer  to
      MicroNote	 15, entitled "Q-bus Hardware Bootstraps"

      Since the ROM sockets on these  boards  may  be  used  for  user-written
      application  code	 as well as boot code, it is important to note what is
      different on the two boards.  Besides the	 sockets  being	 of  different
      size,  the ROM on the two boards has another difference.	The ROM on the
      MXV11-BF is window mapped and may be used under application  control  to
      address  up  to  8  KB.	The  MXV11-A ROM is direct mapped and can only
      address 256 bytes.  Thus, an upgrade would require new ROMs and possible

								Page 2


      application recoding.

      For more detailed	 information  concerning  MXV11-BF  issues,  refer  to
      MicroNote 19.

      For more detailed information concerning MXV11-A issues,	refer  to  the
      archived MicroNotes listed in appendix A.


      Summary:

      When upgrading from the MXV11-A to the MXV11-BF or choosing the MXV11-BF
      over the MXV11-A, three important features are obtained:


      1) 22-bit compatibility - allows use in large memory systems
	 (The MXV11-BF memory can only be configured to start in the
	  lower 512 KB.	 It does, however, decode all 22 lines of
	  address which makes it usable in systems with up to 4 MB.)

      2) More memory (although its non-parity feature creates some software
	 support issues if used with RSX or RSTS)

      3) Support for boot ROMs that will boot MSCP devices such as the RX50
	 and RD51 and will provide cache diagnostics for the LSI-11/73.