Does anyone recognise this logo? DD? - Page 1
Forum section: electronics / general

author: TomS_
author_rank: Frequent Contributor
timestamp: December 02, 2020, 07:30:49 pm
content: I bought a few random eurocards, just for some reverse engineering practice since they all have parts I am reasonably familiar with.But I cant find any information about these cards when I search for the model numbers printed on them. Was hoping to potentially track down some datasheets to see how far off I am with my understanding and maybe compare my schematic to the manufacturers if available.Maybe someone recognises the logo of, presumably, the manufacturer?

author: Labrat101
author_rank: Unknown
timestamp: December 02, 2020, 07:56:12 pm
content: I guess you checked if it was D&D Electronics, LLCare there any other clues .

author: CJay
author_rank: Super Contributor
timestamp: December 02, 2020, 08:07:12 pm
content: Pic of more of the card might be helpful but Eurocard is such an old standard and there are *so* many companies that used it for niche products, in house stuff, custom one off stuff, if you don't know what the card was used for or fitted into then it's going to be a slog.Schematics are going to be similarly hard to find but it'll be interesting to see what turns up, never know, weird unexpected things happen here, like the designers of ancient test gear turning up to give tips on repair or design choices so who knows...

author: TomS_
author_rank: Frequent Contributor
timestamp: December 03, 2020, 02:09:56 pm
content: Quote from: Labrat101 on December 02, 2020, 07:56:12 pmThey dont seem to be related.No real clues, just some model/part numbers which all start with DD.e.g. the "optoisolated input" card is model DD8019. It has a PAL on it with a label that reads "DD4098".

author: TomS_
author_rank: Frequent Contributor
timestamp: December 03, 2020, 02:19:49 pm
content: Bigger photo of the optoisolated input board attached.The pinout of the bus doesnt seem to match any of the different bus standards I could think of. But as you say, anyone could basically come up with their own for their own applications.Ive got a load of PRO-LOG datasheets/manuals for a wide variety of cards that include schematics and functional descriptions, and even code examples for working with them. Was kind of hoping to find something similar for these cards, but Im doubting they even exist if I cant even find a reference to the model number of the card itself.

author: Labrat101
author_rank: Unknown
timestamp: December 03, 2020, 03:49:19 pm
content: Do a close up of the bottom of the card as well .Some times it can be helpful

author: GlennSprigg
author_rank: Super Contributor
timestamp: December 04, 2020, 12:03:51 pm
content: I TRIED!! (but failed..) using my normal techniques, but decided to show what/how I attempted it, thatmay benefit others!'Google' has a little used/understood feature, where you can search 'Images', as well as for 'text'.If you go to...https://www.google.com.au/imghp?hl=en&tab=wi&ogblor look at the Google Window after 'Images' afteryou search for some Text, you will see a 'Camera' Icon at the right-hand end of the search-bar. Clicking on that Icon, andthen selecting "Upload an Image", you can select an image/photo that you have, and it searches the Internet for somethingsimilar, and shows the results! It is NOT perfect by any means, but often helps you. So what I tried was this...I downloadedyour 'Photo', and edited it to just contain the 'Logo' we are interested in. As in this .jpg file...Now I used some Vector Conversion software, to create a smooth result, and saved it as a .png file...I then used BOTH of these, (without success this time!), using the above 'method' for image-search. Seems too obscure!!Then I assumed the letters were 'DD' and performed a search for... 'DD icon'. Found hundreds of results, but not yours!I wondered if it was supposed to be 'OD' and searched for... 'OD icon'. Same result.I even tried just 'D' in case the 'black' part was just meant to be a Shadow!! Nope...I hate things like this beating me, but maybe this can help others trying something similar !!!

author: CJay
author_rank: Super Contributor
timestamp: December 04, 2020, 12:11:06 pm
content: But the annoying thing is I *think* I've seen that logo before.It doesn't look horribly difficult to reverse though, even the programmable logic is probably pretty simple to decode, it may not even be protected

author: GlennSprigg
author_rank: Super Contributor
timestamp: December 04, 2020, 12:19:38 pm
content: Quote from: CJay on December 04, 2020, 12:11:06 pmAnd I 'think' I've seen it before too!! Argh...But then again, the brain plays tricks on us! I've been slowly watching (all??) the episodes of 'Combat!' from around 1950.I would SWEAR that some episode descriptions/names I have seen, but am often proved wrong!!

author: fcb
author_rank: Super Contributor
timestamp: December 04, 2020, 12:51:31 pm
content: Double D Electronics Ltd, UKhttp://www.ddelec.co.uk/

author: GlennSprigg
author_rank: Super Contributor
timestamp: December 04, 2020, 12:55:01 pm
content: Quote from: fcb on December 04, 2020, 12:51:31 pmKudos to you!!!!

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 01:48:04 pm
content: Quote from: fcb on December 04, 2020, 12:51:31 pmSmashed it right out of the park!"Sadly" it looks like they may have moved on from these products, they mostly seem to be involved in RF from what their website lists these days. I might just try sending them an email and see if they would happen to have any old datasheets laying around, never know!

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 01:52:19 pm
content: Yeah, I managed to figure out one of the PALs just by toggling inputs and using my Z80 knowledge to make some educated assumptions about which pins should be which.They are pretty simple boards really. Z80 PIOs and Intel 8255's and a sprinkling of other logic. Got to start somewhere I suppose.Still would be nice to see how close I got - or how far off I am. :-)

author: CJay
author_rank: Super Contributor
timestamp: December 04, 2020, 02:05:26 pm
content: Quote from: fcb on December 04, 2020, 12:51:31 pmBrilliant and really impressed they're still in business too.Now I need to know if they've got schematics available

author: CJay
author_rank: Super Contributor
timestamp: December 04, 2020, 02:09:40 pm
content: Quote from: TomS_ on December 04, 2020, 01:52:19 pmYeah, that's the fun of it, I bought a pile of LED signboards a few years ago just to break for parts and found every one of them had a 6502 based controller inside, had loads of fun reverse engineering the GAL chips and disassembling the ROM contents.Really must dig out that info and post it somewhere.

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 02:23:14 pm
content: Quote from: GlennSprigg on December 04, 2020, 12:03:51 pmYou sort of beat me to it. I was going to try this, but given I couldnt really find anything to begin with I didnt fancy my chances - as you found out.Strange that even though they are still an active company, google knows nothing about them!Probably they will now though.

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 02:44:07 pm
content: Quote from: Labrat101 on December 03, 2020, 03:49:19 pmThere really is nothing on the back to help, just the model number of the card!edit: srsly wtf eevblog. A tiny bit of skin from my hand and my image "fails security checks"??

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 02:47:12 pm
content: Quote from: CJay on December 04, 2020, 02:05:26 pmIve sent them an email to ask for datasheets/schematics if they have them. Lets see how I get on.

author: CJay
author_rank: Super Contributor
timestamp: December 04, 2020, 03:10:38 pm
content: TBF, there's very little to it,32 identical looking Opto isolated ports with some simple protection, connected to the PIO chips, buffered 8 bit databus via the LS245,, some address/select decoding via PAL/GAL IC4 and that's about all she wrote, it's a nice exercise to reverse it and if you've a retro habit then it'd make a nice IO card for a homebrew computer, the DIN connectors are still available...

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 03:18:58 pm
content: Yeah. Im doing a lot of retro type stuff lately, which is largely the reason why I picked these up.It has all been reasonably predictable given that Ive studied the PRO-LOG datasheets for similar cards a bit. Actually Im more interested to see how close I got with the control signals themselves, because the rest of the circuitry Ive been able to figure out quite easily. Ive made some educated guesses based on what I observed while playing with the PAL and knowing how the Z80 toggles its signals, if I had the schematic for one of the boards that would at least let me know if I got them right.I probably cant do much with the cards themselves, the bus is non standard, or I would have to build everything to match this bus, but there are parts I could play with. Its more of a distraction than anything else. 2020 doesnt really deserve much attention.

author: TomS_
author_rank: Frequent Contributor
timestamp: December 04, 2020, 05:32:52 pm
content: Well, Steve Davies from Double D got back to me and was quite happy to share what datasheets he had at hand, and gave me permission to share them onwards. He said he had wondered when some of the company antiques would show up.No schematics, but thats fine, all part of the fun. But one of the datasheets was the bus spec itself, so that will solve a lot of mysteries!A bit too big to attach here, so I'll share them via Google Drive.https://drive.google.com/drive/folders/1DX_1GLvSW83BOVAiIqxBl32db86Inqna?usp=sharing