New MTG Kawai R100 ROM Switcher

As you may have seen in my previous post, my Kawai R-100 Drum Machine came with a 3-EPROM “soundswitcher”. Since this is no longer available, I thought I would make my own. It’s not an exact clone of the Drumware Inc board. First, I used different logic … just a personal choice. Second, I eliminated the ribbon cable to cut down on cost. It looks like there is just enough vertical room to pop the board on top, so that’s what I did. In my unit the Kawai ribbon cables are such a mess that it’s hard to close up the lid already. Finally I did a 2-layer board compared to the old Drumware single-layer board that was probably taped up by hand. In fact this is how I used to make SRAMĀ  memory expansions myself in the late 80’s. I even advertised them in the back pages of Polyphony magazine (for JX3P, OB DX, Polysix and a few others).

Kawai R100 ROM Switcher

Kawai R100 ROM Switcher


Kawai R100 EPROM Switcher Installed

Kawai R100 EPROM Switcher Installed


Kawai R-100 Drum Machine Front showing the switch

Kawai R-100 Drum Machine Front showing the switch

I also silk-screened the pin information on the top.

Read my previous post for more background info.


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5 Responses to New MTG Kawai R100 ROM Switcher

  1. grantb4 says:

    By the way, I may make a kit at some point, but I don’t have all the parts gathered yet.

  2. Ron joseph says:

    I’d love a kit. I have 2 r100s.One has the expansion,one doesn’t. The expansion never worked fully, figured the EPROM was screwed.

  3. Adrian says:

    Hi Was just wondering if you have any of these boards still avaliable?

  4. roman says:


    do you sell or trade these boards? i’ll be interested in 5pcs – as i own 7 R-100. : )


  5. grantb4 says:

    Yes I make these 3X switchers as well as a 4X variation. I have them on eBay.

    I don’t usually have 7 made at a time, but we could work something out if you want to email me.


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