11/04 floppy problems

[Beastly Wolf]

NIkolai!

Your problem MIGHT be because somebody shuffled the cards for you!

There are some classical caveats when it comes to the UNIBUS based system.
a) There must be an uninterrupted grant chain all the way and no holes.

b) There are two types of slots. DMA (also called a MUD or Modified 
Unibus Device) and NON DMA. Default is non DMA. To enable DMA you cut a strap 
on the wirewrapped backplane. (*cringe*)...
This suggests that there are also two types of GRANT cards. One resembling
a dual QBUS grant card but with green handles and one very small "playing
card type" single card with no handle that can be (with force) inserted
backwards and thus burn the bus.

c) There must be a terminator card in the last position of the chain.
I am at a customer site right now and do not have access to my library so
I can not be more specific.. If you have any documentation handy, you should
be able to use above information and find the exact information you need.
If not, you should be able to locate the faulting device by "shortening" 
the bus. You start with CPU and a mem card and install the terminator 
directly after. See if you can deposit and examine stuff into RAM. Then 
put in the device directly after the last MEM card and test it and so forth.
Eventually the system will fail and you have located the problem.
Either remove the problem or get back to us. =)

Note: With no documentation of the devices in question you have more problems.
Some UNIBUSes are standard UNIBUSes. Others are special UNIBUSes for special
device configurations. 

The UNIBUS PDP11 (or VAX) is a challange for the technically interested 
person. =)

Oh yes... You can bypass devices by using the UNIBUS cable (a long stiff 
white flat cable with UNIBUS connectors in each end). Each UNIBUS sub bus is
connected with the previous with a UNIBUS continuity card that consists of
a short UNIBUS cable and two dual cards joined together to form one unit.
If you want to bypass a device, take out the continuity from the start and
end of the device, install a UNIBUS cable at the last position of the
previous sub bus system and the first in the sub bus after the bypassed
device.
UNIBUS cables, continuity cards and grants (and also the terminator) all 
go in the same position across the bus and in no other place.

One error here and it is BURN baby BURN! =/

/Lars

On Mon, 9 Mar 1998, Warren Toomey wrote:

> In article by Nickolai Zeldovich:
> > I'm having a somewhat interesting problem with my PDP-11.. I'm trying to
> > boot a 11/04 from a 8" floppy drive, but DX, DX0, and DX1 all make it hang
> > up (RUN light goes out). Would you know what this would mean? I'm not sure
> > if this question is really appropriate for the list, sicne it's not
> > UNIX-related, and I've had little luck with newsgroups (seems my newsfeed
> > is quite flaky).
> > 
> > -- [ Nickolai Zeldovich // nickolai at zepa.net ]
> 
> I'm punting this to the mailing list ONLY because Nickolai's news access
> is limited. Can someone help him with the problem?
> 
> 	Warren
> 

Received: (from major at localhost)
	by minnie.cs.adfa.oz.au (8.8.5/8.8.5) id XAA08220
	for pups-liszt; Mon, 9 Mar 1998 23:45:12 +1100 (EST)
X-Authentication-Warning: minnie.cs.adfa.oz.au: major set sender to owner-pups at minnie.cs.adfa.oz.au using -f