DEC H7260 PSU fault

Antonio Carlini a.carlini at
Sun Jan 28 12:53:44 CST 2018

On 27/01/18 23:38, Jules Richardson via cctalk wrote:
> With the drive actually hooked up to the controller, I'm getting "?54 
> RETRY" messages when it's trying to boot - however, I'm not entirely 
> sure what device it's trying to boot from! Maybe it's attempting the 
> TK50, or via Ethernet. I still need to read up on that and work out 
> how to force it to attempt a disk boot.


should do it (although you may have yours set up for DUA1 or whatever 
depending on the drive jumpers).

> One other issue is that the RD53 was in the second bay (and hooked up 
> to the associated cables) - it makes me wonder if it was just an 
> auxiliary disk, and the system originally had another drive in the 
> first bay (containing actual OS) which has been removed.

I think you get a different message if the disk is there but it has no 
valid boot block.

If you had a later CPU (say the KA650) and anything other than the very 
earliest ROM (which may never have made it out to the field) then you
get a bunch of additional commands (like SHOW DEVICE) which would help 
diagnose what's what. You would be able to tell whether the M7555
was visible at the correct address, for example.

The suggestion of booting it as a satellite from a VMS cluster node is a 
good idea (although if you've never set this up before then it may take you
some time to get it set up properly). SIMH makes this quite easy I think.


Antonio Carlini
arcarlini at

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