Can anyone identify what this board is/does?

Tom Gardner t.gardner at
Sat Dec 2 16:03:08 CST 2017

My understanding is that DZU made disk storage subsystems including both drives and control units and that many if not all into the 1980s were copies of IBM disk storage products.

The recollection is that IBM 2314 era SCU used a form of TROS where words were strips of film that punched a hole a one or a zero at each transformer (core) location to route the current around or through a core.  The 2841 may have had the same technology.  This could be done relatively easily in the field.

At Memorex they used wire rope as TROS for the same function as I think did other PCMs.  This was smaller and allowed faster clocks than film strips but was difficult but not impossible to field upgrade.  Next generation SCUs went to writable control store's loadable from FDD's.

So this might be a 2314 era TROS so its date could be early 70s given first PCM 2314's SCUs didn't ship until the early 1970s so I have a hard time thinking the Russian system beat US capitalism :-)    
But if they copied the 2841 and it used TROS then it could be late 60s


-----Original Message-----
From: Tony Aiuto [mailto:tony.aiuto at] 
Sent: Saturday, December 02, 2017 8:45 AM
To: Brent Hilpert; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Can anyone identify what this board is/does?

On Fri, Dec 1, 2017 at 11:05 PM, Brent Hilpert via cctalk < cctalk at> wrote:

> On 2017-Dec-01, at 7:12 AM, Tony Aiuto via cctalk wrote:
> >
> >
> > EBay listing for a "Soviet Magnetic Ferrite Core Memory Board". It 
> > looks like 20 something gigantic cores and a lot of diodes. I am 
> > guessing it is some kind of ROM, but it doesn't look like a rope 
> > memory. And maybe the cores are not cores at all, but some sort of 
> > inductor. I've not seen this before.
> That's very funny.
> It looks to be a core rope memory that hasn't been programmed.

I think that is the most likely case.

> Other organisations might be possible, but it looks like a 
> pulse-transformer type of core-rope, where the cores are just for 
> ordinary induction, not switching/memory cores.
>         - the matrix of black what-look-to-be diodes would be 
> data-wire isolation diodes
>         - the little brown 'stools' are wire routing posts
>         - you can see the mulit-turn sense windings (bluish) already 
> present on the cores
>         - above the cores are the sense amplifiers or 1st stage 
> thereof
>         - there is one wire through all the cores, perhaps a test wire 
> for core and sense amp response
> Each data-wire would start at one of the solder pins in the pin matrix 
> on the left, weave through the cores to encode the data, turn back 
> 180, then 90 degrees around one of the stools to drop down and 
> terminate at the solder pin by an isolation diode.
> There would be another board for decoding the address to 1-of-x and 1-of-y.
> I didn't count precisely but it looks like it would be 256 words of 20 
> bits.
> That might be a date code of 6847 on a cap (or is it 6B47?), so 
> perhaps earlier than the listing-stated 1981.
> Actually, it kind of hints at it in the description: "With out 
> Firmware ROM wire (empty slots)"

Ah, you read the description. I just looked at the title and saw "with the firmware". My addled brain made the leap to a external firmware, which made no sense. "firmware ROM wire" would be a clear case for rope memory.

On Fri, Dec 1, 2017 at 11:32 PM, Charles Anthony < at
> wrote:
> The last picture has "???-5". Some googling takes us to
> "DZU is a factory in Stara Zagora , a major producer of magnetic disk 
> storage devices (hard drives and floppy disks) during the rise of 
> computer production in Bulgaria in the 1970s and 1980s, century. Today 
> it is part of VIDEOTON Holding ZRt., Hungary [1] ."
> The article says it was a disk drive factory, but maybe...
> -- Charles

Given the cleanliness of the board and other things the seller is offering, my guess now is that this NOS from the DZU plant.

Thanks, everyone.

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