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Thread: Internal OPL3 ISA 8 btis (PCXT)

  1. #1

    Default Internal OPL3 ISA 8 bits (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 2nd, 2020 at 11:46 PM.

  2. #2

    Default

    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.

  3. #3

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    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.

  4. #4

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    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

  5. #5
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    Default

    Quote 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, Olivetti M24, or Logabax 1600
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  6. #6

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    Quote 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

  7. #7
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    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

  8. #8

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    Quote 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

  9. #9
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    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

  10. #10

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    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:


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