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M24SP DB25 to DB9 adapter

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    Thanks Chuck(G).

    I really didn't know this.

    Well, I feel better now.

    Now I am scared to say the name of the famous database from the Big Blue. It was DB2 but probably they intended DE2 as it was connecting data with people?

    Or the famous Aston Martin cars, were probably DE5 and DE8, not DB5 (1955) and DB8 (195?

    Back to the software again, let's imagine the troubles of the software company Ashton Tate, when the made a fortune selling millions of licences of DB2, DB3 etc. also to people who were convinced to purchase a connector, instead.


    Just kidding guys. Life is hard. Let's smile with some italian humour.


    Originally posted by Chuck(G) View Post
    The D-subminiature line of connectors was introduced by Cannon (now ITT Cannon) in 1952 and, from the beginning coded the shell size. It's language-and country-independent.

    So your DE9 connector has the same shell size as a VGA connector, which is a DE15. It's very simple, until you get to the weird stuff, such as DB13W3.

    This logical system falls apart when talking about, for example, the Atari ST ACSI connector (19 pins in a non-standard shell, so not A B C D or E). but still referred to as "DB-19". Good thing that they're not made anymore.


      Originally posted by pevalcas View Post
      On the other side, I'm building a couple of board MCE2VGA 2.0 designed by Luis Antoniosi.
      This project is very interesting but complex. It assumes that the VGA monitor is quite stupid and converts the video frequeny by using a frame buffer and regenerates new picture with new fixed frequency.

      We know this kind of adapters akready in home computers scene to convert lowres PAL/NTSC video signals, with or without interlace to VGA or even HDMI. The basic idea is aready quite old and you might find this kind of circuitry already in some Commodore Amiga computres as a 3rd party addon from the early 1990's called "flicker fixer" to use with standard VGA monitors. That basically works, but it has a lag, or call it a conversion delay. That means, what you later see on the modern monitor is not the "now" what the video controller produced just now, but it is the past. For MS-DOS-shell uncritical, but specially for gaming unwanted.

      This is not necessary because modern TFT have this intelligence already inside, they always have to use the frame buffer internally because a TFT works completely different than a CRT. It only depends on the software which is in the TFT if it is able to detect old compiter's video timing to be able to convert that to it's internal framebuffer. But that also has a minimal lag, that's why the real home computer gaming freaks prefer the original CRT monitors.

      So using such an 'intelligent' frame buffered video adapter, plus moderrn TFT, this is already two lags. What you see, is the past of the past. Some quick games impossible to win. Additionally you gave another sensible device there.

      So I prefer that simple stupid conversion of RGB+I to VGA color signal, and letting the TFT doing the rest.

      I propose to use some of the NEC Multisync TFTs, specially those of the 4:3 19/21 inch series as they have the most flexible video timing detection, the 17 inch models are mostly more limited. Some of my favourites are 1990nxp and 1990sxi (and ther 21 inch brothers 2190 nxp/sxi if that is not tooooo big). And my favourite for old computers in general is now the 1970nxp, it even supports real interlaced modes of Commodore Amiga and ATARI Falcon 030 machines. That one seems to be able to 'eat' every video format as long it is analogque RGB+H/V-Sync from 320x200 up to 1280x1024 between 50Hzi up to 70Hz progressice. If you go to those ATARI and Commodore computers forums you will also find some peoples reporting about other TFTs that flexible.

      So I am focussing on the final result of the above tested circuit. Currently I have two 1990nxp, three 1970nxp.
      Last edited by 1ST1; June 19, 2020, 09:12 PM.


        Hey 1944GPW,

        I did the same research on ebay Italy.

        DB9 got 1899 hits.
        DE9 only 55.

        Ok, I will start a new crusade. Lets replace E with D in the alfabdt and vicdvdrsa. Why we have eone this mistakd all this timd?

        Good Goe!
        Byd folks.

        Originally posted by 1944GPW View Post
        You could nitpick this, as some might like to.

        Let's look on

        DE-9 (plug,socket,connector)
        64 results for DE-9 (plug,socket,connector)

        DB-9 (plug,socket,connector)
        2,956 results for DB-9 (plug,socket,connector)

        I wouldn't worry about it too much, we know what you mean.


          I don't bother if it is called DB or DE, I just want the right thing. I think this kind of discussion is out of topic.


            It's okay, I'm still sensitized to the D-sub blunders. I've long given up the battle of "baud" vs. "bits per second", audio-frequency modems being just a memory today.
            Reach me: vcfblackhole _at_ protonmail dot com.