L15 Cal Trig Crate  Review of Who lives in What VSB Address Space
   ------------------------------------------------=====--------------

                                                            Rev.  1-APR-1994


Review the Restrictions on the Use of VMX Address Space
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  The Hydra-II is able to access the VSB Bus in the region VSB address range
  $00C0 0000   through  $FFFF FFFC.   This is mapped to DSP addresses
   0030 0000h  through   3FFF FFFFh.   Longword accesses from the DSP to
  the VSB make the most sense.

  As we use it the MVME135 is able to access the VSB Bus in the region
  $0010 0000  through  $FFDF FFFF.  The MVME135 can map any region within
  this range into VSB address space (map at 1 MByte boundaries i.e. A20)




 The Following Shows the Setup When Using Only a 32k Byte "First Bank"
 of the Fancy 214 with a Separate MVME-214 Providing Short I/O Memory
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When in "Load" mode the Fancy-214 appears to the 68k as a 32k byte block
from address  $0100 0000  through  $0100 7fff.  It is accessed over the
VBS buss.  Note that the whole address range  $0100 0000  through  $010F FFFF
on the MVME135 card is mapped to VSB.

This same 32k byte (8k longword) bank when in "Load" mode appears to the
Hydra-II C40 DSP in addresses  0040 0000h  through  0040 1FFFh.


When in "Read" mode the 32k byte block on the Fancy-214 appears in addresses
$0030 0000  through  $0030 7fff.   Note that this is on the VME Bus #2 in
the L15CT crate and thus it is visible to the VBD but only indirectly visible
to the MVME135's 68k over the Vertical Interconnect.  Over the Vertical
Interconnect this bank appears from  $1030 0000  through  $1030 7fff.

When a Fancy-214 is in "Read" mode it is not visible to the Hydra-II C40 DSP.



>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

So Let's Use the following VSB Address Ranges  (This is what I wanted to do  )
---------------------------------------------  (but I had to back off because)
                                               (because the Short I/O bank   )
                                               (of the Fancy 214 was not work)
                                               (ing with the VBD  1-APR-1994 )

First Bank of the Fancy-214   (128k bytes A24/A32)

   Lets use VSB addresses  $0100 0000  through  $0101 FFFF  to access the
   First Bank of the Fancy-214, the 128 KByte bank.

   The 68020 on the MVME135 will access the First Bank of the Fancy-214
   using the addresses shown above but note that the whole 68020 address
   range  $0100 0000  through  $010F FFFF  is mapped to VSB.

   The Hydra-II will access the VSB address range for the First Back of
   the Fancy-214 using the DSP addresses  0040 0000h  through  0040 7FFFh.


Second Bank of the Fancy-214   (2k bytes Short I/O)

   Lets use VSB addresses  $0104 0000  through  $0104 07FF  to access the
   Second Bank of the Fancy-214, the 2 KByte bank.

   The 68020 on the MVME135 will access the Second Bank of the Fancy-214
   using the addresses shown above but note that the whole 68020 address
   range  $0100 0000  through  $010F FFFF  is mapped to VSB.

   The Hydra-II will access the VSB address range for the Second Back of
   the Fancy-214 using the DSP addresses  0041 0000h  through  0041 01FFh.