Heathkit H-11 restoration questions

From: Ethan Dicks <ethan_dicks_at_yahoo.com>
Date: Mon Oct 4 15:09:53 1999

--- allisonp_at_world.std.com wrote:
> > The fact that the machine hangs solid when the card is where it's
> > supposed to be may be a clue that the it's permanently stuck interrupting.
>
> Depending on backplane the grant may not end-up where you guess it is.

I was assuming a sinusoidal AB-AB chain starting from the slots labelled
"A" and "B" (out of A, B, C, and D). Now... the one twist is that the cards
are installed with the CPU facing the bottom of the cage (solder side up),
but the keys on the backplane connectors are a dead giveaway.

> My memory is fuzzy on this but I think Ht-11 (heath os) did not like RTC
> <line event> interrupt and would hang on that.

Hmm... I don't have any HT-11 disks, only RT-11. But the LTC *was* enabled.
 
> Yes, also DLV11 or the heath serial card both should have HALT on BREAK
> enabled. <both support it as do the 11/03>

I didn't even try that. For now, because of bootstrap considerations, I'm
running with an 11/23plus CPU and a VT-220 (because it's close).

Speaking of bootstraps, what did the H-11 come with stock? BDV-11? Custom
Heath board?

-ethan


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Received on Mon Oct 04 1999 - 15:09:53 BST

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