Help setting up a SBS/Bit3 PCI-to-VMEBus cards

[Christian R. Fandt]

At 14:54 05-07-05, Ram Meenakshisundaram wrote:
>Hi Chris,
>
>Drivers for the SBS 616 are available for Windows XP/Linux/Solaris here:
>
>http://www.sbs.com/products/software/280
>
>I picked mine up on ebay.  I also picked up a SBUS-to-VME one as well, but
>its from Performance Tech SBS915 as well.
>There is currently one on ebay for a relatively cheap price (picked mine
>from the same guy):
>
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=51239&item=3983996787
>&rd=1&ssPageName=WDVW
>
>And its New in Box condition like mines.  Now, if my board needs to use J2
>connectors, do I need to install that on top of the terminators as well?

J2 connections are not from the VMEbus but can be described as usually an 
interface to the outside world. Let's use an example of, say, the MVME147* 
family of processor boards, in which the P2 connector on the module has 
connections to SCSI devices, serial ports, Ethernet, etc. And in this case 
of the example MVME147* board, there will be used a transition module as 
illustrated on a certain auction site using the number 5786398985 
(MVME712/M). Note in the pictures the largest connector on the surface of 
the '712 board. Its the P2 connections jumpered over from P2 on the '147 
board. SCSI terminators are the yellow resistor packs. The 5-pin SCSI 
connector is on the upper right edge. Except for needing to follow the SCSI 
termination rules, no other terminators are used on this board.

The MVME320 is an MFM disk I/F module which, IIRC, has the disk cable 
connections out the P2 conn in addition to the ribbon cable connectors on 
the front panel. My '320 is buried in the collection at the moment, but I'm 
rather sure it too does not have terminators for the MFM disk cables. Cable 
lengths should be kept short as possible.

So, all this rambling is to say that terminations, such as used on the 
VMEbus, are not *normally* needed on P2. Just depends on what is hung off 
the P2.


>The transputer boards has its own J2 plug which I installed on all the
>slots.  Why do you need terminators if the chassis is limited to only 5
>slots and all the slots are occupied???

Even on a short-length VMEbus, signal "ringing", or reflections, can occur 
with the short pulse lengths and fast rise-times that may be found on the 
bus signals. Transmission line theory is involved here.

What does P2 connect to on your transputer boards?

Regards,  Chris F.

NNNN

>Thanks,
>
>Ram

Christian Fandt,    Electronic/Electrical Historian
Jamestown, NY  USA      cfandt at netsync.net
         Member of Antique Wireless Association
         URL: http://www.antiquewireless.org/