re: VME bus confusion

["Dr. Pete Jemian" <jemian@arev.mrl.uiuc.edu>]

> 
> 1) There MUST ALWAYS be a board of some kind in EVERY slot of the VME
>    crate starting on the left and working right.  If you MUST have
>    a missing board, you may simulate it by installing the BG and IACK
>    jumpers often found on the VME backplane.
> 
>    Failure to follow this rule causes very strange things to happen. 
>    Common sense does not seem to apply to this easier... don't think
>    that just because a board does not generate IRQs or operate as a bus
>    master that things will still be OK.  We have seen otherwise!

Not to throw grit in the gears of progress but the VME crate nearby has
a pretty wide gap between the few modules on the left side of the crate
and the MVME 162 coprocessor running HiDEOS.  Numbering from 0 at the
left of the crate, slots 0-5 are filled, 6-13 are empty, 14 is filled
(the 162), & 15-19 are empty.  No complaints from EPICS, VME, or ...
It seems to work.  Must be a miracle.  However, on reading the above
advice, this crate will be told to get with the program.

>     If anyone ever calls me again with a problem that is caused by
>     this... the service charge will be a 6-pack of Miller Highlife in
>     bottles.  Viva le Champaign of Beers!
> 
> 
> --John
> 

This, too, can be arranged.

Pete