johnw (04/13/83)
Converitng an 18 bit system to a 22 bit system is quite simple
if your backplane has wire wrap pins. It takes less than 30
minutes. The tools required are a screwdriver, a hand wire-wrap
tool with wire, and an ohm-meter for testing. If you don't have
these tools, refer the job to qualified electronic techinician, or
DEC.
All that's required to convert your system is to add the 4
missing address lines to the backplane. (No boards need to be
modified!). The missing lines use BUS pins BC1, BD1, BE1, and BF1.
FOr a complete description of the LSI-11 BUS (Q-BUS) see chapter 12
of the 1981 "Microcomputers and Memories" handbook.
To locate the desired pins, place a double-height module, such
as the 11/23 processor, in front of you with the component side up
and the contact fingers pointing away from you. Note that the
contact fingers are separated by a gap in the middle of the board.
Starting from this gap and moving toward the right, the contact
fingers on the top side of the board are BA1, BB1, BC1, BD1, BE1,
and BF1. On the bottom side fo the board they are BA2, BB2, BC2,
etc.
To add the missing address lines, remove all of the boards
from the backplane and remove the backplane. On the back of the
backplane you'll find wire wrap pins. Each pin is connected to one
contact finger. Locate pin BC1 of slot 1 and, using your wire wrap
tool, connect it to BC1 of slot 2. Connect BC1 of slot 2 to to BC1
of slot 3 and so on throughout the backplane. Repeat these
operations for pins BD1, and BE1, and BF1. If you use a hand wire
wrap tool, and the kind of wire that doesn't require stripping,
it's a very easy task. If you have a large multiple backplane,
it's only necessary to bus the backplanes which actually have 22
bit boards in them.
After completing the above, use the ohm-meter to check for
continuity on the sockets. Also verify that you have not accidently
connected anything to pins BC2, BD2, BE2, or BF2. Look for the
wires to form a neat, repeatable pattern.
ihnp4!ihldt!johnw