DDI-1 interface

salvogendut · 21:54, 18 July 25

I am looking to purchase a DDI-1 interface for a CPC464 (either original or clone) . Ideally I should be able to connect an external drive/gotek to it and use easily. I am located in Italy

Richard_Lloyd · 23:08, 18 July 25

https://www.facebook.com/share/p/1F9bVkAgjD/?

Piotr Bugaj makes a DDI-1 clone.

eto · 08:53, 19 July 25

Quote from: Richard_Lloyd on 23:08, 18 July 25https://www.facebook.com/share/p/1F9bVkAgjD/?

Piotr Bugaj makes a DDI-1 clone.

Slightly related: He also announced that he will close down his company end of the year.

Quote from: salvogendut on 21:54, 18 July 25I am looking to purchase a DDI-1 interface for a CPC464 (either original or clone) . Ideally I should be able to connect an external drive/gotek to it and use easily. I am located in Italy

Be aware that you need the original floppy drive to power the controller module. The controller gets its 5V from the floppy. Modification is possible but not too simple.

If you want a GOTEK anyway you should consider the DDI5 or DDI6 also made by Piotr. They combine the DDI with GOTEK and 512K RAM (DDI 6 also ROM board) in a single device. The price is a bit high but still cheaper than getting the individual parts and a lot less hassle as you don't have to deal with any modifications.

There are also other expansions that might make sense. The ULIFAC and the upcoming PicoROM also provide DSK access, ram and rom and are much cheaper - but don't contain a real disk controller.

salvogendut · 09:14, 19 July 25

Quote from: eto on 08:53, 19 July 25If you want a GOTEK anyway you should consider the DDI5 or DDI6 also made by Piotr. They combine the DDI with GOTEK and 512K RAM (DDI 6 also ROM board) in a single device. The price is a bit high but still cheaper than getting the individual parts and a lot less hassle as you don't have to deal with any modifications.

Ideally I'd want something simple with just an external connector for the gotek/disk (and the gotek/disk will be powered by an external power supply). Even though I like the idea of DDI5 and 6 they are expensive and I don't like that they are trying to be everything (ram expansion, FDC emulator and external connector). I'd be happy with something like a DDI with just the external connector. I have a ULIfAC already and I like it the way it is but would love to be able to connect a real disk to a 464

Bryce · 11:20, 19 July 25

Quote from: eto on 08:53, 19 July 25Be aware that you need the original floppy drive to power the controller module. The controller gets its 5V from the floppy. Modification is possible but not too simple.

It's not that difficult, it just involves adding a wire to the DDI-1 PCB:
https://www.cpcwiki.eu/index.php/File:DDI_Modification1.png

Bryce.

salvogendut · 12:37, 19 July 25

Quote from: Bryce on 11:20, 19 July 25
Quote from: eto on 08:53, 19 July 25Be aware that you need the original floppy drive to power the controller module. The controller gets its 5V from the floppy. Modification is possible but not too simple.

It's not that difficult, it just involves adding a wire to the DDI-1 PCB:
https://www.cpcwiki.eu/index.php/File:DDI_Modification1.png

Bryce.

Thanks @Bryce !!! I wonder if there are DDI clones out there that can be easily built as DIY projects

eto · 15:12, 19 July 25

Quote from: Bryce on 11:20, 19 July 25It's not that difficult, it just involves adding a wire to the DDI-1 PCB:
https://www.cpcwiki.eu/index.php/File:DDI_Modification1.png

If you are doing only this you would have a short the moment you attach the GOTEK. You at least also need to precisely cut wires on the flat cable or do a few more mods on the DDI itself. Unfortunately I don't remember where I found the document that explained how to mod the DDI-1 without the need for cutting wires.

Quote from: salvogendut on 09:14, 19 July 25Even though I like the idea of DDI5 and 6 they are expensive

A used DDI-1 is usually not much cheaper than a new DDI-5.

Quote from: salvogendut on 12:37, 19 July 25I wonder if there are DDI clones out there that can be easily built as DIY projects

I looked for such a project too in the past and haven't found a project but the schematics are available so it should be easy to build a DDI.

xesrjb · 15:58, 19 July 25

Quote from: eto on 15:12, 19 July 25I looked for such a project too in the past and haven't found a project but the schematics are available so it should be easy to build a DDI.

Ask @hans from VzEkC. He rebuild the Vortex Controller without ROM Socket...

xesrjb

Rabs · 16:30, 19 July 25

Quote from: eto on 15:12, 19 July 25I looked for such a project too in the past and haven't found a project but the schematics are available so it should be easy to build a DDI.

Quite a few posts on the subject of a DDI-1 clone.

DDI-1 DIY There is a re-drawn image of the schematic on post #9, which I have not looked at in any detail.
DDI-1 CLONE ver. 2.0 ready
DDI-1 clone - some help needed

I have two D765ACs in my spares pile and can still source them on EBay but not sure about sourcing the FDC9229.

eto · 12:56, 20 July 25

Quote from: Rabs on 16:30, 19 July 25Quite a few posts on the subject of a DDI-1 clone.

DDI-1 DIY There is a re-drawn image of the schematic on post #9, which I have not looked at in any detail.
DDI-1 CLONE ver. 2.0 ready
DDI-1 clone - some help needed

Seems none of those is publicly available for DIY.

I've recently seen that there are D765AC-compatible successors that don't require a data separator and no inverters. That could reduce the footprint a lot. However I did not fully understand if they can easily be used in the CPC or if there are other pitfalls like the clock or Ready signal.

Instead of the FDC9229 in some 6128s the FDC9216 was used. That one is quite easy to source at least from China. I just recently bought two from a German seller (NOS) for 7€ (2 ICs, incl. shipping) to repair one of my CPCs. As the disk interface is it's own subsystem in the CPC 6128 we probably also could use its schematics to build a DDI-1.

Bryce · 13:03, 20 July 25

Quote from: eto on 15:12, 19 July 25If you are doing only this you would have a short the moment you attach the GOTEK. You at least also need to precisely cut wires on the flat cable or do a few more mods on the DDI itself. Unfortunately I don't remember where I found the document that explained how to mod the DDI-1 without the need for cutting wires.

Only on the connector at the end of the flat cable. The connector in the middle has the terminals removed from the power carrying wires.

Bryce.

Rabs · 13:07, 20 July 25

Quote from: eto on 12:56, 20 July 25
Quote from: Rabs on 16:30, 19 July 25Quite a few posts on the subject of a DDI-1 clone.

DDI-1 DIY There is a re-drawn image of the schematic on post #9, which I have not looked at in any detail.
DDI-1 CLONE ver. 2.0 ready
DDI-1 clone - some help needed
Seems none of those is publicly available for DIY.

I've recently seen that there are D765AC-compatible successors that don't require a data separator and no inverters. That could reduce the footprint a lot. However I did not fully understand if they can easily be used in the CPC or if there are other pitfalls like the clock or Ready signal.

Instead of the FDC9229 in some 6128s the FDC9216 was used. That one is quite easy to source at least from China. I just recently bought two from a German seller (NOS) for 7€ (2 ICs, incl. shipping) to repair one of my CPCs. As the disk interface is it's own subsystem in the CPC 6128 we probably also could use its schematics to build a DDI-1.

Indeed, nothing appears to be fully publicly available. I have all the symbols in KiCad and I have the footprints for the edge connectors but I would just be copying the schematic without any background knowledge.

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DDI-1 interface