Help to identify FDC interface

[Richard_Lloyd]

Hello all. As part of a recent eBay purchase there was this Floppy Controller interface.

The M27128 EPROM has the standard AMSDOS 0.5 ROM image in it.

Does anyone know what it might be. I've not tried to connect it yet, thought I'd try and identify it first.

Cheers, Richard.

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[TotO]

Looking the parts used, it match more or less with an hand made DDI-1 interface.
It can be a Vortex too, because few addressing decoding change.

[GUNHED]

Can you read the ROM content?

[Richard_Lloyd]

Can you read the ROM content?

Yes. It's byte for byte identical to the standard AMSDOS/CPM ROM7.

[GUNHED]

Yes, then probably a self made DDI-1 interface. 

[Bryce]

I'd guess it was made by a company. A hobbyist would either socket everything or nothing. The PCB is also made of an early FR4 material which would have been extremely difficult to find and expensive. Most hobbyists at the time would have been using hardened paper PCB's. It looks very similar in style to the expansions (including floppy controller clones) that the company Slogger made for the Acorn Electron and other 8-Bit computers.

Here's a picture of the Slogger Pegasus 400 Floppy controller for comparison.

Bryce.

[TotO]

I'd guess it was made by a company. A hobbyist would either socket everything or nothing. The PCB is also made of an early FR4 material which would have been extremely difficult to find and expensive.

That is a possibility. Now, it is a common practice to add sockets for the expensive circuits, but not those that cost the price of a socket. To me, it looks like the printed boards we make manually in the high school electronics lab (except that we welded better).

[Skunkfish]

Didn't Siren Software sell their own DDI-1 interfaces as some point? (or did I imagine that?).

I wonder if it might be one of those?

[TotO]

A think a company will put its name/brand on the PCB. No picture of the back side?

[Richard_Lloyd]

Back view - no clues here?

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[TotO]

NAA was drawn with a pen on the back layer before insolation, and the soldering skill can be better.
For me, it is undoubtedly a board made by a hobist in electronics to make his own DDI-1. Really cool.

[Animalgril987]

Looks like the solder missed half the pins on the 74LS132...

[Bryce]

The soldering looks ok, but I also notice that they bent the corner pins on the IC's, another thing that hobbyists rarely do. It may of course be a prototype from a commercial device?

Bryce.

[TotO]

Hum... Bending a corner pin is a tip you do to avoid the ICs to be removed after returning the PCB to solder it.
But I agree, it can be a prototype board. Just, if it was for a commercial usage, the brand is missing, no?

[GUNHED]

Well, just try the interface with FutureOS and you'll if it is compatible to Amstrad FDC or Vortex FDC. If it supports drives DS0 and DS1 only of DS2 and DS3 too. 
Of course FutureOS runs on CPC464 like shit, just ignore the smear of the mouse pointer.

[gerald]

My 2 cents :
PCB is clearly not a hobby made one (or a very rich one): Vias, CNC cut edge, what looks like HASL finish (or whatever era
equivalent, clearly not silver as it would have tarnished with age).
Soldering is on par with my campursoft ROM box    : hand soldered.
Not every small company could afford wave soldering at that time. Manual placement and soldering was business as usual for small batch.

[Richard_Lloyd]

Today, I connected the interface only (no drive) to my CPC464. It works.
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The drive cable with the interface is unusual because the drive connector is male/pins and not female/socket.
When I next have spare time I will crimp a socket onto the cable and connect a Gotek for some more tests.
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More info soon. Richard.

[Richard_Lloyd]

We have a working DDI-1 clone! (with a Gotek but I assume a real drive will be fine).
I haven't tried a B: drive but inspection of the PCB found that DS1 line is NOT connected so I guess it's A: only.
The interface takes it's power from the CPC464 line 27.
Sorry for the poor (phone) photos but they show everything.
Photo 1 shows the arrangement before connection to the CPC464
Photo 2 shows the first screen and a ROM list from Utopia
Photo 3 shows a CAT of the CPM 2.2 DSK on the Gotek USB
Photo 4 shows CPM run from the DSK
Interesting.......

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[GUNHED]

DS0 is sufficient so enable two drives, see original DDI-1 interface.