From: Ed Chapman

To: All Field Personnel

Date: Tuesday, January 21, 1997

Copy: Mark Greening

Harold Welch

Lee Henry

Jack Lynch

Subject: Inbus Processor Speed, on Inbus Upgrade

It has been noticed, upon upgrading the new style Inbus Multi-Bus Board, some or all of these boards do not operate at the correct speed necessary.

This document should outline steps necessary to correct this malfunction.

Step 1) Not all back-plane in the field are jumpered correctly to handle the newer Inbus Multibus cards. The older stand-alone 8840s early back-planes using strictly the older DTI boards, may or may not be jumpered correctly. "Refer to IMNY2026, ground, sheet 1 of 2".

Allow yourself enough time to correct this malfunction; this means removing and replacing the back-plane.  

Tools Needed:

OHM Metre
Solder Iron, Solder

Optional Tools:

Remove the back-plane, rotate so the first slot(slot 1) is towards the top. Looking at slot one from the solder side(SS) or back side, measure ohms between PIN 1 and PIN 15; they should be physically connected. The ohms check should be made with all the cards removed from the back-plane. With all the cards removed, looking from the CARD SIDE(CS), you may see a jumper. If there is no provision for this jumper, you must actually solder a piece of wire from pin 1 to pin 15 on SS of back-plane. See IMNY2026.

This grounding of BPRN, must follow for every card. Most of Impact card’s have an external piggy-back board iSBX344 or our Net 2 Card. This prevents the cards from going into consecutive slots; they normally skip every other slot. Logic flow, with ground on slot 1, pin 15 follows through any MultiBus card and out pin 16; and pin 16 connects to the next logical slot’s pin 15. Thus for each empty slot, PIN 15 must be physically connected to PIN 16. This becomes apparent when looking at drawing IMNT2026 sheet 1 of 2 and the SS of the back-plane.

If for some reason this does not look straight forward to you, things look pretty bad for you and you most likely should not proceed.

Note: On some very old back-planes, the actual P1 plug may be missing on CS of slot 2, but the traces are there on the SS for slot 2. It does not matter if the plug is there or not; if the trace is there, the jumper must be in place to complete the circuit. If for some strange reason there are 2 empty slots, the jumper must bypass both empty slots.

Remember, the signal come in on pin 15 of MultiBus card and goes out on pin 16 of MultiBus card; and then must make a logical connection of the next pin 15 of the next slot where a PCB will go.

Step 2) At this point, you may wish to re-install the card cage or you may wish to not install the card cage for easy testing of the cards.

For all Inbus cards, ensure the following jumpers are installed. E183 to E184, see NY2026 sheet 2 of 2. CBRQ/ should be installed on every Inbus card(s). E181 should not be connected to E182. The Inbus Boards, at this time, should always be run at 5 MHZ. Running this board at 8 MHZ can cause initialization errors.

For only one Inbus Card, normally the first card PUC or MAC, BCLK/ (E179 to E180) and CCLK/ (E190 to E191) need to be installed. See NY2026 sheet 2 of 2. Technically, any card in the back-plane can be used to drive BCLK/ and CCLK/, but Impact standards dictate the first card in the first slot is used to do this. This is why we always configure the PUC or MAC as the first card in the first slot and it always has BCLK/ and CCLK/ jumbered.

Very important note: only one card in a physical back-plane can be used to drive BCLK/ and CCLK/.

Where you are using a stand alone link enclosure, the same rule holds. The difference in this case, however, one of the cards in the link enclosure must be use to drive BCLK/ and CCLK/. Example: If you have a stand alone link enclosure, with say 2 links boards installed and nothing else installed in the back-plane, you must install BCLK/ (E179 to E180) and CCLK/ (E192 to E191) on one of the link cards.

Step 3) With all cards installed into the backplane, power the backplane. With a logic probe or volt metre check to ensure the last pyhsical card in the backplane has PIN 15 referenced to ground or PIN 1 on its PLUG 1.

Using a monitor port cable and PCPLUS to ensure each card is operational.

Following Drawings are IMNY2026 Sheets 1of 2 and Sheets 2 of 2.