Huw Davies <H.Davies_at_latrobe.edu.au> wrote:
>One question, what's the difference between the AB and CD slots in the
>backplane?
On *some* backplanes, there is no difference. A dual-high board could
be plugged into the CD side just was successfully as in the AB side.
In other backplanes, the AB side is the Qbus side, and the CD side is
set to connect adjacent boards so that they can communicate (such as
the VSV11, the RLV11, and the 11/83 and its PMI memory).
In yet other backplanes, you find that it is Qbus in the AB slots and
CD bus in the CD slots for part of the backplane (BA23 = three slots,
BA123 = 4 slots) and then it switches to Qbus in both the AB and the
CD sides.
Bottom line -- make sure you know what backplane you are plugging
boards into before you do so. Also, make sure that quad-high options
which can plug into both Q/CD and Q/Q have the CD jumpers on the board
set correctly.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry zk3.dec.com |
| Unix Support Engineering Group | (home): mbg world.std.com |
| Compaq Computer Corporation | addresses need '_at_' in place of ' ' |
| 110 Spitbrook Rd. ZK03-2/T43 | URL:
http://world.std.com/~mbg/ |
| Nashua, NH 03062 | "pdp-11 programmer - some assembler |
| (603) 884 1055 | required." - mbg |
+--------------------------------+-------------------------------------+
Received on Mon Aug 24 1998 - 19:29:42 BST