New finds and some h-11 help

From: Christian Fandt <>
Date: Thu Nov 18 16:24:19 1999

Upon the date 12:35 PM 11/18/99 -0800, Ethan Dicks said something like:
>--- "Zane H. Healy" <> wrote:
>> > 1. Digital M7264
>> PDP-11/03 processor
>> > 2. H-11-5 Serial i/o
>> > 3. H27 Floppy i/o
>> > 4. H-11-5 Serial i/o
>> > 5. M8044 CB
>> 16 KW RAM
>> > 6. M9400 YB
>> 120-ohm Terminator
>> > 7. WHA-11-16 16k x 16k Memory
>> >
>> >First question, does it matter how these boards are plugged into the
>> >backplane?
>To a certain extent - the CPU should be at one end of the Qbus, the M9400
>at the other. Other stuff is not so critical.
>> If so, where do they go? What are boards #6 and #7? The
>The M9400 is at least a Qbus terminator if not a Qbus terminator and boot
>card... I forget what the "YB" designator means, and my H-11 is not in
>front of me (it has a KDF-11 "PDP-11/23+" CPU card in there, anyway).
>The WHA-11-16 is some third-party card with which I am not familiar.

That's the Heath-designed memory card. The "W" means it was factory wired
and tested.

>> Well, I would think that 6 & 7 are reversed, but I'm not familair with the
>> H-11, so there might be soemthing wierd going on there.
>It is wierd - the backplane is upsidedown - the cards go in with the solder
>side up. It threw me for a loop the first time, too. Fortunately, I didn't
>"fix" the problem and power up.
>BTW, that 4x6 connector is Heathkit propietary. I have never seen one
>anywhere else except hanging up on the wall of the local electronics
>warehouse about 15 years ago back when that kind of connector was more
>common. It's a type of Molex connector.

Hmm, I gotta find an old Molex catalog (IF I kept an old one in my design
library still stored in boxes). Seems it was a rather familiar type from
our using Molex products at my ex-employer.

>If you have _any_ DEC async boards, I'd pull the H-11-5 and go with a DLV11-J
>or the like. I have an H-11-5. It's *not* in the H-11. It's on the shelf.
>I do not have any docs, though, before you ask. I am stymied with the H-27
>interface card. I have tested all the TTL ICs, but this thing still locks
>up the Qbus when it's plugged into the grant chain with no gaps. With gaps,
>it begins to read the floppy at boot time, but as soon as the boot code
>turns on interrupts, because the interface is in the wrong place, the system
>hangs, waiting for the interrupt that never comes.

I've got two complete H-11 systems but have not yet got them running. Back
burner project setting with all the others. Should get to them I guess so's
I could help several here who have them. I could look up stuff if either of
you need info. Seems Allison has had one for years that she hotrodded with
a better CPU, etc.

>I've been working on other systems recently - a pdp-8/e and pdp-8/L,

Well, that should keep one busy for a spell :-)

Regards, Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA
        Member of Antique Wireless Association
Received on Thu Nov 18 1999 - 16:24:19 GMT

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