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sn76489an compatible Verilog core, with emphasis on FPGA implementation and Megadrive/Master System compatibility

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# JT89 FPGA Clone of sn76489an hardware by Jose Tejada (@topapate)

You can show your appreciation through:

* [Patreon](https://patreon.com/jotego), by supporting releases
* [Paypal](https://paypal.me/topapate), with a donation

sn76489an compatible Verilog core, with emphasis on FPGA implementation and Megadrive/Master System compatibility.

This project aims to make a Verilog core that will:

* Produce signed output waveforms, with no dc offset
* Produce accurate volume
  * Have volume limiting like reportedly Master System had
  * Different volume settings for noise channel as reported
  * Test if Megadrive 2 version had different volume and apply it
* Reported variations on noise signal length
* Use one single clock for all registers, making it easy to synthesize and constraint on FPGAs
* It will fit well with [JT12](https://github.com/jotego/jt12) in order to produce the Megadrive sound system
* Have separate output channels, so they can be mixed using the interpolator before the sigma-delta DAC

If you use JTFRAME, this project will integrate naturally with it. If not, you can use the .qip file for Quartus in the syn/quartus folder.

## Using JT89 in a git project

If you are using JT89 in a git project, the best way to add it to your project is:

1. Optionally fork JT89's repository to your own GitHub account
2. Add it as a submodule to your git project: `git submodule add https://github.com/jotego/jt89.git`
3. Now you can refer to the RTL files in **jt89/hdl**

The advantages of a using a git submodule are:

1. Your project contains a reference to a commit of the JT89 repository
2. As long as you do not manually update the JT89 submodule, it will keep pointing to the same commit
3. Each time you make a commit in your project, it will include a pointer to the JT89 commit used. So you will always know the JT89 that worked for you
4. If JT89 is updated and you want to get the changes, simply update the submodule using git. The new JT89 commit used will be annotated in your project's next commit. So the history of your project will reflect that change too.
5. JT89 files will be intact and you will use the files without altering them.

## Use Cases

This project has been used in:

* [Genesis MiSTerFPGA core](https://github.com/MiSTer-devel/Genesis_MiSTer)
* [Kicker arcade core](https://github.com/jotego/jtkicker)
* [Yie Ar Kungfu arcade core](https://github.com/jotego/jtkicker)
* [Konami's Ping Pong arcade core](https://github.com/jotego/jtkicker)
* [Mikie arcade core](https://github.com/jotego/jtkicker)
* [Track'n Field arcade core](https://github.com/jotego/jtkicker)
* [Road Fighter arcade core](https://github.com/jotego/jtkicker)
* [Super Basketball arcade core](https://github.com/jotego/jtkicker)
* [Exed Exes arcade core](https://github.com/jotego/jtgng)

## Related Projects

Other sound chips from the same author

Chip                   | Repository
-----------------------|------------
YM2203, YM2612, YM2610 | [JT12](https://github.com/jotego/jt12)
YM2151                 | [JT51](https://github.com/jotego/jt51)
YM3526,OPLL,OPL2       | [JTOPL](https://github.com/jotego/jtopl)
YM2149                 | [JT49](https://github.com/jotego/jt49)
OKI 6295               | [JT6295](https://github.com/jotego/jt6295)
OKI MSM5205            | [JT5205](https://github.com/jotego/jt5205)
sn76489an              | [JT89](https://github.com/jotego/jt89)

jt89

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