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Internal OPL3 ISA 8 btis (PCXT)

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    Internal OPL3 ISA 8 btis (PCXT)

    I designed a new low profile OPL3 sound card from the scheme provided by the existing TexElec Resound OPL3 in which, as you can see, it is a four-channel sound card based on the Yamaha's YMF262 chip and use of two high quality WIMA film capacitors per channel to prevent the passage of direct current in the audio output.

    In this case, I thought that with the two primary channels it is more than enough. As an experiment by TexElec it is fine but no game or application of the time uses the other two. On the other hand, I have replaced the port selection DIP with one of 2 switches, to select with the help of an SPLD only four possible ports, including the default 388h used by Adlib and the 220h to "cheat" some games pretending to be a Sound Blaster ... I think the rest is too much and they are still purely experimental, with this measure I also gain some space and eliminate other chips involved in this task:



    As you can see, I have also decided to make it internal regardless of the external audio jack in order to be used in current PC cases that have the typical USB + Audio connector on the front, so that a bracket is not necessary , being enough with one of the blind brackets that come standard with the box.

    I have launched with this project to provide a sound card to my NuXT Monotech tucked into a low profile desktop, although it could be used in any other PCXT and compatible.

    Soon in my Tindie store in two flavors (Fully assembled or only PCB)... it will be with ENIG + Gold Fingers finish for greater durability and reliability in the transmission of the ISA port signals, I just have to check the routing and scheme before proceeding to the PCB manufacturing order.
    Last edited by spark2k06; February 3, 2020, 12:46 AM.

    #2
    Well, according to this website the ports are:

    220h or 240h (selectable) and 388h -> Sound Blaster Pro II, 16, 32, AWE32/64 and Live, ESS 688, etc.

    Only 388h -> Adlib Gold, Windows Sound System

    So in the SPLD I will always keep the 388h present and leave the DIP Switch configuration such that:

    * 0 - 0 [Only 388h]
    * 0 - 1 [388h + 220h]
    * 1 - 0 [388h + 240h]
    * 1 - 1 [388h + 260h]

    So as for the design of the PCB, I just have to update the silkscreen.

    Comment


      #3
      New design for better finishing of slot and updating silkscreen for better combinations of I / O ports:



      However, since the SPLD will be in socket any programmer can reconfigure it as best suits your needs, obviously the silkscreen will no longer serve as a reference.

      Comment


        #4
        Hi
        Years ago when I first got a sound card for my machine, I wanted to play with the sound generation. I forget what level the sound chip was but I believe it was OPL3. I'd started out with the data sheet and was fiddling with the registers and the file format to create different effects. I was kind of clumsy so I wanted to improve my ability. Someplace I'd gotten an editor that was designed to edit the sound files. It was freeware but it was suppose to be a leading in to buying the full editor.
        I took my file that I'd been working on for a couple of weeks and feed it into the editor. When I got done I wanted to play back what I'd modified.
        Oh, heck! Many of the effects that I'd done were not there. It seems the editor not only deleted parts of my original sounds but didn't even make a backup of my original work. ( No Sale to Me! ). I never did get back to it and I was really pissed at the author. He'd violated one of the first rules of writing software, " Do no harm! ". Of course I was just a beginner then and should have made a backup.
        Dwight

        Comment


          #5
          Originally posted by spark2k06 View Post
          As you can see, I have also decided to make it internal regardless of the external audio jack in order to be used in current PC cases that have the typical USB + Audio connector on the front
          How large is the market for people putting ISA motherboards in modern cases?
          Offering a bounty for:
          - A working Sanyo MBC-775 or Logabax 1600
          - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

          Comment


            #6
            Originally posted by Trixter View Post
            How large is the market for people putting ISA motherboards in modern cases?
            getting larger all the time seeing as how finding AT-style cases has become impossible

            Comment


              #7
              I used to see people selling ATX I/O plates with an AT keyboard hole years ago but not lately, if there was a market for ATX conversions those bezels would still be popular (and many early ATX cased will happily fit an AT motherboard.
              What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
              Nubus/ISA/VLB/MCA/EISA cards of all types
              Boxed apps and games for the above systems
              Analog video capture cards/software and complete systems

              Comment


                #8
                Originally posted by Unknown_K View Post
                I used to see people selling ATX I/O plates with an AT keyboard hole years ago but not lately, if there was a market for ATX conversions those bezels would still be popular (and many early ATX cased will happily fit an AT motherboard.
                is it because they are no longer popular, or because the original stock has been depleted? I doubt anyone had new ones manufactured at any time in the past 15 years

                Comment


                  #9
                  You can still buy blank ones easily enough so setting up a jig to punch out one hole shouldn't be that hard.
                  What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
                  Nubus/ISA/VLB/MCA/EISA cards of all types
                  Boxed apps and games for the above systems
                  Analog video capture cards/software and complete systems

                  Comment


                    #10
                    Just having enough to cover the cost of a PCB run on my part is enough. I do it for fun and mainly to give a solution to my current configuration of my NuXT motherboard, by the way ... I think it will look good:

                    Comment


                      #11
                      Done!



                      https://www.youtube.com/watch?v=0QMfLWs73HM

                      https://www.youtube.com/watch?v=FN3jSZ-MhRM

                      https://twitter.com/spark2k06/status...37209004482560

                      Comment


                        #12
                        Version 1.2 Kikad project available here.

                        - Modification of YMF762 and YAC512 footprint dimensions

                        - Increased thickness of some power tracks

                        - Silkscreen of 74HC245 changed to 74HCT245

                        - Added two resistors in the back layer to solve the problem of version 1.0

                        Comment


                          #13
                          You might be interested in this more detailed description of the SoundBlaster and AdLib I/O port usage etc.:
                          http://shipbrook.net/jeff/sb.html

                          Comment


                            #14
                            One can access OPL2 and OPL3 at four different port ranges :

                            388-389 Single OPL2 (Adlib, SB, SB Pro, SB16)
                            388-38B OPL3 (Adlib Gold)
                            2x0-2x3 Dual OPL2 / OPL3 (220, 240 SB Pro Base, 220, 240 260, 280 SB16 Base)
                            2x8-2x9 Single OPL2 (210, 220, 230, 240, 250, 260 SB Base, 220, 240 SB Pro Base, 220, 240 260, 280 SB16 Base)
                            My Retro Computing and Vintage Gaming Blog : http://nerdlypleasures.blogspot.com/

                            Comment


                              #15
                              Originally posted by Great Hierophant View Post
                              One can access OPL2 and OPL3 at four different port ranges :

                              388-389 Single OPL2 (Adlib, SB, SB Pro, SB16)
                              388-38B OPL3 (Adlib Gold)
                              2x0-2x3 Dual OPL2 / OPL3 (220, 240 SB Pro Base, 220, 240 260, 280 SB16 Base)
                              2x8-2x9 Single OPL2 (210, 220, 230, 240, 250, 260 SB Base, 220, 240 SB Pro Base, 220, 240 260, 280 SB16 Base)
                              388-38B OPL3 is also available on the SB Pro 2 and the SB16.
                              My Retro Computing and Vintage Gaming Blog : http://nerdlypleasures.blogspot.com/

                              Comment

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