Kawai R-100

Kawai threw itself into the mid-80′s drum machine scene with a kick ass flagship that was right at home in the new wave. Behold the R-100.

keyboard ad

8-polyphonic PCM drum machine with 24 12 bit samples
Velocity sensitive pads
8 individual outputs, MIDI, DIN & tape sync

In addition to all these great specs, some folks seem to have versions with more than one sample rom in them and toggles to select from, I guess, up to 72 sounds! Shouldn’t be hard to create new roms and fit them in.

But, this drum machine has been on the back burner for a long time. Almost too pretty looking/sounding to ever crack it open.. almost. I’ll get to it someday.
In the meantime, this post is up for you to begin a discussion about bends, mods and experimenting with new roms.
Who among you will be the first to comment with all the real dope.

keyboard ad Here’s some interesting links:

Operator’s Manual.
Service Manual.

The elusive rom switcher!
Ian sent photos of his rare tech installed Rom switcher. You can see where the board fits in place of the one chip.. And infer how the 4 position switch should function to switch between up to 4 roms. This should give anyone an idea of how to get started making a replacement rom board. Click any for a closer view. More info will come later.
R-100 rom switch exterior R-100 rom switch board R-100 rom switch pulled R-100 rom board front R-100 rom board back R-100 rom board close


    Well Thom

    think you’ve neglected that r100 for long enough! How could i resist a brand new post? The r100 is a beast! I have two, one which i have bent, the other has the rom swapper and i didnt wanna touch that yet.

    Well it has a plug on it so remember plug=danger, but the 40 pin sound roms hold a wealth of bends, but there are a few points that crash and reset it, but alot of scope for sound mangling, haven’t ventured further than the roms though, but there is alot of chips in there!

    I would like to push it abit more, anyone up for the challenge?

  • hey ian, congratulations on being the first to pick up the reins! I have a feeling this is going to be an epic post.
    And so we can start talking the same language here, could you list your chip set and could i trouble you for a description of (& some photos would be nice too) of the ‘rom swapper’ hardware?

  • nice1 Thom good to have you on board, i’ve just sent you the photos you require and you can read the chip numbers off the photo, but there is room for 4 chips so thats 96 sounds!

    so where do we start? i’m willing to crack mine open again and go further on the board but would be good if we could try and work out what is what, yours looks in really good condition!

  • Has anybody managed to dump the R-100 ROMs? I’ve just dumped both the MCU and PCM ROMs inside my R-50.

  • Hey phil

    not actually started this mod yet, been gathering info on how best to do this. I lack a 40pin adaptor for eprom reader. I’m presuming its the r-50 roms you have dumped, yeah? I have three rom chips for the r100 that need to be dumped. was it straightforward for the r50? i have an r50e that could be be dumped also, maybe you could turn your r50 into an r50e…………

  • I read my R-50 PCM ROM (MN234001KAA) as an MX27C4100. The data looks/sounds reasonable. It’s stored in a 12-bit format of some sort.

  • thanks phil will give this a try soon, battling with another project at the moment, but really would like to take this further, could do you some copys of r50e chips, though i think you would only need the sound rom. email me if you want to chat about this and we can host some stuff here,



  • Updated the post with photos of the rom switching board..

  • i had one of these several years ago with one additional chip installed. i absolutely loved this box but had to sell it. Now I think I’m going to pick one up again because of it’s sequencer’s timing and hard sound however I too am having problems sourcing the additional chips. Any ideas about where to look? I’ve gone up and down the google highway to no avail ….



  • Hey Phil, I can’t seem to read my Kawai roms. You said that you’d managed to get a result by reading it as an MX27C4100….. My eprom programmer doesn’t allow MX27C4100′s, and no other setting seems to get a result either…. Do you know any technical wizardry that could help here? I got the r-100, r-50 and r-50e roms, and obviously willing to share…


  • Squidfanny, Phil and others – Burnkit2600 wouldn’t mind hosting whatever Roms you guys can send. That would definitely be helpful for others no doubt.
    ‘If I have seen farther, it is because I have stood on the backs of giants.’
    -Sir Isaac Newton.

  • hey Dave

    i got a hold of these k50 rom downloads from phil, i will send them to thom and get him to post them. As far as i’m aware phil used a sophisticated piece of equipment to do this (i have the name) i dont think it was one of the cheap ebay rom readers (like mine) will get that done for you. Have you been able to get an expansion board yet?


  • Hi Ian. Yea man, my r-50 came with a (badly fitted) expansion board. It’s identical to yours..
    It doesn’t quite fit correctly into the R-50, but the previous owner decided to just force the lid closed and screw it back together… So the main board was badly warped and a couple of surface mount chips weren’t connecting properly so the machine would crash every time it got too warm :-(
    In the end I de-soldered the 40 pin IC holder, and then soldered the expansion board straight onto the r-50′s main board. It hasn’t crashed since…. :-)

    But according to my badly scribbled notes – “The roms are enabled with a 10k pull-down resistor. The resistor is connected to pin 11, and held high. To enable the rom, the (non 5 volt) side of the resistor is connected to ground.Each rom has it’s own resistor,and a rotary switch connects the ground to each resistor and thus enables the rom.”

    So if my notes are accurate (which they may not be!), then it’s possible to just stack the ROMs on top of each other, and use a resistor to pin 11 and a rotary switch to enable.

    I took a few photo’s, mainly of the expansion board. This one might be useful to someone in the future, –


    Cheers Ian, Cheers Burnkit and happy new year!

  • Hi, i´ve got an R50 and want to add a 555 Pitch Mod. Does anyone know which chip and Pin is used to pick up the clock signal for the whole mix?

    Any help is greatly appreciated


  • I got my R-100 this weekend and I’m loving it. Especially how rediculously huge it is. I ordered some 27C4096s to burn and I’m reaquanting myself with my homebrow AVR eeprom programmer I built for NES rom burning, so I’m hoping to get some custom sounds in this beast. If we can get those R-100 rom images posted somewhere, that would be awesome so I can verify I’m reading mine correctly. This will be awesome if we can get this working. I’m imagining repurposing the cartridge slot for custom sound rom boards.

  • oops, the 27c4096 has the wrong pinout – it was on the same datasheet and I got confused. But some 27c4100s are on the way. Looks like the R-100 uses a 6502 based microcontroller as it’s cpu. I’m going to try to read in my sound rom tonight.

  • Hi Monty, you’ll need an ‘ltc1799 precision oscillator’ (or something similar) to do pitch mod on the r-50… 555 doesn’t oscillate fast enough to get a stable result.
    Just remove to little blue timing crystal (x-tal) next to the drum ROM and feed your precision oscillator straight in.

  • Hi Squidfanny, ….will try that soon. Thanks for the good description& Oscillator tips.


  • Well, I’m still working on getting my homebrew eprom programmer working properly. I called up Kawai though, and they emailed me the R100 service manual – it’s here: http://www.fengland.org/files/R100service.pdf – have fun

  • Some progress: finally got the pcm rom read in and verified. It took many hours, my homemade reader is disgustingly slow. Here it is, in big-endian byte order:
    You can kind of hear the drums in there all distorted if you import it into audacity as 16bit signed big endian at 32k sample rate. Now to figure out how the companding was done – the bottom arc of the waves look folded up. Anyone out there doing anything with their R-100 still/yet?

  • Hi fengland

    i think only you and one other have been able to look into the data on these chips (i was sent a copy of the roms for the r50 but neither me or thom could open them), i think general prommers aint gettin a look in with the kawai’s. I have a set of the expansion chips which i would be willing to put up here if i can get them read, but i’m kinda lagging behind due to not having the right equipment/knowledge. When you say you built your own programmer that sounds like a neat bit of work, can i ask how you went about this? (out of my league but i’m interested :)

    easy now

  • Hi clone2, glad to see someone else on here. I ran into more problems than I expected to building the reader, but the concept is very simple – you just put each address on the ROM address pins, and the data at that location can be read on the data pins – if you hooked up dip switches to the address pins and LEDs to the data pins and entered an address in binary on the switches, you would see the data at that location in binary on the LEDs. I used an atmel AVR microcontroller programmed in C to read in each address from the ROM and send it to a PC on the serial port. It was really just a matter of hooking up the pins and writing a little code. The nice thing about the alesis drum machines people have successfully replaced the sounds on is that the data is stored in standard 16 bit PCM format – the R-100 uses some kind of funky 12bit companded format which will take more to figure out how to convert custom sounds so they’ll be played back right.

  • more success – I’m close to having the sample format decoded. Here’s a wav file of the decoded sample rom – http://www.fengland.org/files/R-100-converted.wav – Sounds pretty good, still a little distorted, my expansion algorithm needs slight tweaking. I’ll create a conversion utility when I get to it – In the mean time here’s the linux c code I used to convert the rom dump to a file which can be imported into audacity as 16bit signed, big endian, 32000 sample rate – http://www.fengland.org/files/convertPCM.c – I used this info to reverse the compression – http://www.rfc-editor.org/rfc/rfc3190.txt

  • Fengland

    your a genius! but i’m like miles behind you…..But i find what your saying really interesting, but my knowledge of code and stuff is really weak. I’ve done the hr16 rom using Justins instructions, but that is it. I think the r100 has real potential, if you dont have one you should try and get a rom swapper, i picked up an r100 with memory cartridge, rom swapper, 3 roms for cheap recently. I feel i have to put the rom switcher to good use. But it will take some time to catch up with you. How are your experiments prgressing at the lab? good luck…….

  • Fengland- I love your DIY method of reading ROMs! It sounds like a great way of understanding what’s going on. That would make a great video demonstration.

    Your .wav sounds good! Looking forward to seeing your progress.

  • Hi all,
    I have looked around for a Kawai R50e sound ROM (image file) without success.
    Maybe someone here have one to share?
    Thanks in advance :)
    compulsion66 (that “a” thing) yahoo (dot) se

  • Does anyone know where I can get a replacement LCD screen for the Kawai R-50? The letters on the LCD of my unit are fading. Ideally I would like to replace the screen with a backlit LCD (possibly red letters on black background or something).


  • Ha haaa, nice to see so many other folks tinkering with the R-100! Lots of great stuff to explore.

    Thought I’d share some info on bending the R-100′s DAC chip (U40). I found that connecting pins 1–12 creates some nice distortion & bit reduction effects. For photos, demos, and more info you can visit http://gumielectronic.net/?cat=13.

    (you guys are welcome to grab any photos, etc. to post here if you want)

  • Nice work, gumi, your bent r100 looks nice.
    I got back to the r100 custom rom burning project with success and was able to burn a custom rom after getting a proper eprom programmer and figuring out that the r100 rom is pin compatible with 27c400 eproms which are burnable with a willem programmer with the 16 bit adaptor. I’m finishing up a little windows/linux gui app to assemble roms since they use a funky 12 bit companded format. I’ll put it up on my site soon if there’s interest. Maybe I’ll get around to building my own rom switcher sometime too.

  • Thanks fengland, and congrats on the custom ROM. Great success! I’d like to give that a try one of these days but my skills in that area are severely lacking.

    I’ve looked a bit into building a ROM switcher as well. I don’t think it would be hard, but there’s one component I’ve been unable to source: the ‘dummy’ DIP socket that is inserted into the R-100′s ROM socket (a la the Drumware version seen here: http://gumielectronic.net/?p=634). I’ve searched Mouser, Digikey, and the other usual suspects, but have found nothing like it, nor anything like the dual-sided DIP socket shown in the ROM switcher photos at the top of this thread. I’m sure I’m just using the wrong search terms. Does anyone happen know what these are called or what I should be searching for? Both versions seem unique in that they mount to the top and bottom of the PCB, with enough pin extension to fit snug into the ROM socket.

  • I think these rom switchers (1 dip to 3)will have been custom manufactured by a german company (their name escapes me, but i think i talk about them further up) this company were responsible for alot of the rom expansion stuff going on in 90′s drum machines, they expanded loads of machines. You may need to buy another r100 if you want a rom swapper, but if i see anything else i’ll let you know. The first one i got was just a bonus when i bought the cheap machine, i didnt really know what it was, the second one i got came with 3 eproms and a memory cartridge. good luck

  • Firstly Fegland, thanks for all your good work, I would certainly be interested in a gui.

    Gummi, I may be mistaken as I do not own a rom switcher myself, but could you not get round this with 2 sockets and some header pins? could hot glue them in if you were worried about it coming loose, but they come in different dimensions so I am sure if you looked around you could find something.

    I own a r-100 bent by circuitbenders.co.uk (before I got the confidence to mod machines myself) and I am curious as to whether it is possible to circuit bend with a rom switcher installed? I imagine it is the same pins that are affected on each chip, so would soldering to points on the main board (or on the header pins on the rom switcher) cause the same effect?

  • Glad there’s some interest in the rom building gui – I need some motivation to put the finishing touches on it! I’ve actually been enjoying the R100 stock sounds too though.

    The rom switcher should be easy to build – I was thinking the same thing – use some header pins to plug into the rom socket on the mother board. Yeah, the data and address lines are hooked in parallel to all the chips – just the chip select line is switched to choose which rom is enabled. So you should be able to hook up your bends to the rom switcher. We could even get some pc boards made if there was enough interest with extra places to solder bend controls on.

  • What kind of numbers would you have to be looking at to make pc boards a viable option? glad to hear you think bending would still be possible, I own 4 bent drum machines and this is easily my favourite, it has the most aggressive tone even before the bends kick in`

  • This place will do 10 3×5″ boards for $66 – that’s the cheapest one I’ve seen.

  • well I’m uk based but I’d happily buy 3, so thats a third of the way there already. I think we could easily get 10 bought. keep up the good work I think there will be alot more interest soon. cheers

  • I wouldn’t mind doing the design and making the investment. I always have a lot of projects going on so we’ll see where I get with it – yeah, having the switcher would be nice.

  • I’d buy at least two of those PCBs right away too. I mean for under $10 a board you really can’t go wrong. Thanks for looking into that fengland.

    In the meantime, thanks for the ideas on using header pins for building a ROM switcher. So, would something like this work?

    @analog monster: Yeah, the bends work great with a ROM switcher installed. I have a switcher by Drumware with all three chips and the bent sounds are sick, sick, sick. All you need to do is solder your wires to the foil (non-component) side of the PCB. That way you can drop in a ROM switcher without having to rewire anything. I’ve posted a tutorial here if you’re interested: http://gumielectronic.net/?p=130

  • messed with my r100 a bit this weekend – I soldered up a cable with header pins plugging into the rom socket with wires hooked up to a big fat 60 pin connector mounted in the cartridge slot – so I’m actually going to move the rom chips outside the r100 into some kind of external bend interface. I’ve just got the rom chip sitting on a breadboard now on top of the R100 – I was getting some nice bends just by disconnecting address lines from the chip. I’ll try to make my board so it could work inside the machine as well since others are interested.

    Gumi, yeah, I used header pins like that – they work but they’re hard to press in – they’re really a little too fat for the rom socket and after pressing them in then removing them and putting back in the rom chip, some of the pins were’nt making a connection any more. Machined round pins might work better.

  • Cool, thanks for the info fengland (btw, I checked out the music out your site, really great stuff, I especially enjoy ‘presseddownhairsong’ and ‘provocation’). Anyway, I think I’ll hold off for now if there’s an opportunity for a proper ROM switcher PCB.

    I haven’t tried severing the address lines; a good idea and I’ll give it a go next time I have it opened up.

    I did try installing a global pitch control (using the GetLoFi 1799 precision oscillator) a couple weeks ago. I couldn’t get it to work and I ended up messing up the 16MHz Xtal. Now the machine locks up when I try to program it. Lucky I have a backup…

  • mine actually bit the dust too =[ the sequencer stopped working – guess I’ll have to keep my eyes out for another cheap one, so progress on this is kinda halted
    Glad you like the music

  • your music is quite nice as well – the cr8000 sounds awesome. I’m working on a dr110 which isn’t quite as cool but is still sounding nice – love that cheesy analog drum sound

  • Ah yeah, the DR-110 is a great sounding machine and has so many options for mods. An easy and cheap micro-808. I have one sitting in a box with mods half finished. I’ve got a bunch of my personal documentation on it, hit me up if you think you can use any of it.

    Sorry to hear your R-100 died. Did you do anything dangerous we should know about?

    I’m installing the DAC bends in my spare right now…I’m never sure how ‘safe’ these bends are though, as I don’t know if they somehow contributed to the death of my first unit, but it just sounds way too mean to pass up. The first one was working fine until I tried to install the pitch mod though, so I’m thinking it’ll be okay.

  • I like to think it just got old and that I didn’t contribute to it’s death, I’m sure that’s wishful thinking though =]
    Yeah, my dr110 is in a half modded state as well. I was using it with the voice mods for a while which was great, but I’m working on midifying it (sequencer sync/triggers) and adding individual volume pots. hopefully I get up the motivation to finish it soon.

  • Hi,
    I have some trouble with my Kawai R-50, he is sending midi data on the same note (C-2) frome each Pad. Even when playing a pre-set pattern. Also sometines the User PAD preset freezes. I guess re-flashing the ROM could help? But where to find the ROM?

    Thanks guys

  • HI shrek_311. Have you looked at the R-50 manual for how to assign MIDI note numbers to the pads? It’s on p.32. Should be an easy fix, or at least it is on the R-100.

    I don’t own an R-50 so I don’t know about the “User PAD” problem you mentioned, though I doubt re-flashing the ROM will help.

  • Hey fengland, I’m curious if you’ve tried the factory reset functions on your R-100 in an attempt to bring it back to life. I was able to revive my R-100 this way, which was locking up the sequencer and showing crazy characters and pattern parameters after I mucked around with the 16MHz xtal.

    Anyway, I found the info in this circuitbenders thread.

    The procedure was originally written in French. Here it is along with the Google translation:

    Pour initialiser les paramètres uniquement: maintenez le bouton [ERASE] enfoncés pendant que vous mettez sous tension. Pour effacer les patern/song: appareil sou tension, maintenez le bouton de sélection n°1 et appuyez sur [ERASE], puis sur [ENTER] deux fois.

    To initialize the parameters only: hold down the [ERASE] button while you power. To clear the patern / Song: penny voltage device, hold down the No. 1 selection and press [ERASE], then [ENTER] twice.

    When I performed both of these procedures my R-100 became 100% functional again, though now I have to re-assign all of my MIDI prefs. But hope it works for you too…

  • gumi, I’ll give that a try – thanks for the tip. Hopefully it fixes it. Though I haven’t missed it much. I just got an mpc60 for that 12 bit sampling action.

  • these avatars are disgusting – mine looks very phallic.

  • Haha. Yeah, they’re kind of weird, but i thought they looked better than the “anonymous shadow man.” They get generated from your email address. If you sign up for a gravitar you can make your own (like mine), and they work on other blogs, too.

  • that’s better.

  • woah, interesting choice. i have that unicorn picture on my wall, someone gave it to me as a gag gift.

  • that’s funny. I have it on my wall in my studio too. From a calendar I found in the trash!

  • Great minds! haha, you guys are funny: “Yeah, i have this unicorn poster on my wall, but I didn’t get it for myself, honest!”

  • yeah, but it’s a bad ass unicorn tromping on an infinite grid. Not some wussy strawberry shortcake ish.

  • Not some wussy strawberry shortcake poster at all. top quality carnival game prize product.
    the print is masculinly laminated to a board right above the bk2600 legacy panel.
    look at all that majesty.

  • that’s nice – I need to mount mine on some wood like that.

  • well, the r100′s kinda working – some of the reframe screen have garbled crap on them but I can record and play sequences. Thanks for the tips on resetting it. just had a good jam with the dr110 synced to it using the trigger out

  • Hey, i just added the R100 service manual, along with a bunch of others to our manuals folder..

  • I have a R-100 I want to sell. Does anyone know what they’re worth now? Anyone interested?

  • dunno, I got mine for $50, seems like about what they’re worth

  • I’m assuming there is no progress on the development of a rom switching board complete with bend points? I’m still really interested in the idea. I’ve more projects than space at the moment so its no rush its just been quite a while since I checked in

  • ended up putting mine towards a trade for a 606 – I kinda miss it though – I’m looking at an r50e now to continue this project – or maybe I’ll keep my eye out for another r100 – my old one was partially broken anyway – would be nice to be able to sync the r100 to the 606. here’s a fat track I made with my r100 right before I traded it – nice crunchy 12bit. micromoog and ax73 on there too: http://soundcloud.com/fengland/diaper-rash – anyway if anyone wants to sell me their r100/r50 let me know.

  • Still couldn’t find a R50e ROM (image file) :(
    Please send me one if you have it, thanks in advance!
    compulsion66 (that “a” thing) yahoo (dot) se

  • I am now the proud owner of a CNC milling machine, and I am on the hunt for a kawai R50 or R100. I shall be making a rom selector as soon as I have got an r50/100 cheap enough (I’m not toying with my current one its the first pro audio bend I did its too sentimental) but I currently do not have any of the other roms to play with, nor have I the tech needed to do it myself.

    So has anyone sucessfully ripped the rom data so it can be burnt onto a fresh chip? how many different rom images have we got? If I can get the roms to test it out I will happily make a rom selector board for anyone who wants them and they will be very very cheap

  • @analogmoster: I would be very interested in such a selector! I have a R-100 with just a non-standard ROM and I’d like to have also the standard sound. Of course it would be nice to have some more ROMs to choose from. polyhedron ( at ) gmx (dot) de

  • Analogmonster and polyhedron,
    We at Burnkit2600 have been meaning to start supporting this machine with new drum roms for awhile. We’ll get there pretty soon I think. When that’s ready there will be a sudden need for rom switching devices for sure.

  • count me in on those ROM switchers…!

  • Hi! I’m new here…
    I often design PCBs (synth modules for http://www.befaco.org)and will be very easy for me do design a switcher if this can help somebody.

  • Hey all,
    so Squidfanny very kindly lent me his expansion board for the R-100 with 3 roms. I read and cloned them successfully. I piggy backed the 3 27c400 and wired them to a 3 position rotary switch so you can now toggle through the 3 different banks. As far as I can tell the roms are the r-50, r-50e and r-100.
    Oh yeah, I am working on a R-50. I lifted pin 12 of each rom (the output enable). To select the rom the switch connects the relevant chip’s pin to where pin 12 was on the board. While not in use pin 12 should be pulled up with a 1k resistor to 5V.
    I tried to do this using the CE pin but didn’t get success.
    I can send you the rom files and any pictures if you need em.

  • Hey Al,

    that’d be great if you could post the rom files somewhere. I just got a great deal on a R-50e so I’d love to be able to expand the sounds. if it helps I can rip an image of my rom to verify it’s the same as the one you have.

  • All official kawai r-100 and r-50 roms published somewhere would be amazing please! I have set myself the challenge of rewriting the OS on my cheetah MD16 to give better midi implementation so I will soon have the equipment needed for multiple drum samples in my beloved r100 too

  • So can anybody supply me with some of the different roms? I am hoping to build a rom switch asap

  • I put the 3 roms I read up on my website. You can download them there.

  • amazing thanks so much for that!

  • Just to let you guys know, I really appreciate the service manual posted, and Al for the binaries. I successfully burned the R50 and R50e chips using AMD’s AM27C400 EPROM and wired up the expansion board myself. Talk about labor intensive! I would recommend it to people wanting to practice some precision soldering. Again, thanks so much for the info and keep bending.

  • expansion board design and soldering are not a problem for me. Finding a way to burn 16 bit eproms are. How are you guys doing this? I have both a pickit 2 and a genius g540 programmer, as well as arduino and tinyISP, and I will be willing to build anything if it will get this working. I have found very few burners listed as able to burn AM27C400s, the only affordable one being a PRO GQ-4X, which is not a priority purchase when I currently have no other 16 bit eprom projects

  • Hi- I have not done any ROM work with the Kawais yet. But I have an EPROM burner from sivava.com, and it looks like this adapter might do the trick for $12. I might be persuaded to buy it to help with the ROM switching project. :)

  • Thanks for the heads up, just bought that burner+adapter. Once its arrived I will be building a new switcher board, with bend points and will make the eagle layout available

  • Cool, I can’t wait to see that!

  • Interested in this too, there is good documentation regarding bend points on the roms and dac at gumi electronics site


  • Hello, I have Kawai R100 drum machine but it seems like was a modified for circuits bend and IC ROM chip with samples is missed… does anyone have EPROM image or please explain me what model of IC I need to burn factory sounds for this machine? or I would buy IC with EPROM… thanks!

  • All the info you need is above. see http://www.exfade.org/kawai-r-50100-roms/ for r50 r50e and r100 roms, and http://gumielectronic.net/?p=622 for some more. you will need a 27c400 eprom. Alot of programmers wont burn them, some will need an adapter.

    I have the rom switcher designed with 4 rom slots and 18 bend points. As soon as I have some extra roms burnt I will make some boards available. I have a sivava/willem programmer with 16 bit adapter and I’m using the same AMD AM27c400s as above. I cant even read then verify as each read pass is different – until this is sorted there is no point even attempting to write. I can read and write to 4k 2732s no problem. Any ideas?

  • well sivava now stock a different 16 bit adapter to the one I bought 6 months ago. I’ve bought one in the hope that it will resolve the problem and I can get these rom switches into production, we shall see. Once I have some programmed the first place I will post the news is here

  • Hmm, yeah, that’s odd. Are you sure you have all the DIP and jumper settings correct? There may be a jumper that selects the adaptor?

  • I’ve done everything I can think of to eliminate human error, I’m now 99% certain its hardware not me. I’m running it from my bench PSU so I’m sure its getting enough juice and I’ve checked the jumpers many times now. All other chips I have programmed using the willem have burned no problem, but this is the first time I have needed to use an adapter not already on the main board. That’s what lead me to get a replacement, which should be here in a week.

  • success! after months of frustration, ive successfully burnt a new rom for my kawai drum machines. It was a faulty adapter all along, not human error. I need to check whether my rom switcher design fits nicely in both the r50 and r100 but once that is done I will get the pcb order in. I expect to have them ready for sale in the next 4-6 weeks. I will update here when they are available

  • congrats analog monster! send us a photo or 2, & keep us updated with your experiments!

  • right, my 1st design wont quite fit into an r50 at the moment so there needs to be a redesign which I will hopefully do tonight. It will work with the r100 fine but I am hoping for the same board for both. It is going to be a very tight squeeze to get it in there, but I have a couple of ideas. There will be eagle board pics available once ive designed the first board to go off to the fab house.

    I am trying to establish exactly what official roms were available. Some places list them as A/B/C, gumi and some other places list them CP2, CP3 but I dont think there are 5 or 6 different chips. The bins exfade provided are the r50, r50e and r100. r100 rom is definitely A as I read my original rom (labelled A) and compared it to the r100 bin. From the sample names I think the r50e is the same as CP2 on gumi’s site. I’m just in the middle of erasing an eprom to burn an r50 rom so I can see if the samples match up to the labels on gumi’s site for CP3. Stupid cheap Chinese eraser takes MUCH longer than it should to erase.

  • I can now confirm that CP1 is r100, CP2 is r50e and CP3 is r50. There appears to be no further official roms. The drumware inc soundswitcher on gumi’s site has 3 rom slots whereas the rom switcher above has 4 slots so I figured there must be at least 4 roms. Perhaps they were just futureproofing. Also if you look closely they do the switching in different ways – drumware toggles pin 12 output enable while the 4 rom switch above toggles pin 10 chip enable.

    I’m experimenting with custom roms at the moment. Very early stages but I may have some news on that soon. The new version of the board is designed and my preliminary tests (a piece of cardboard with some header pins poking through) indicate my design will fit in both r50 and r100 with some gentle bending of capacitors on the main boards so they lay flatter. it is based on the 4 rom switch above. As well as the pull up resistor for each chip on pin 10, they each appear to have another components – possibly a diode but I cant tell from the images. I have put space for them on the board but can be filled with jumpers if not needed. I have to go to work now but when I am back I will have a final check before making an image available and sending a prototype board design off to the fab house

  • Here is an image of the rom switch PCB

    analog monster pcb

  • I’m selling a 3x ROM Switcher on eBay if anyone is interested.



  • Hey~ Just found this webpage. I was responsible for the sound design on the R100 and I designed the Drumware expansion boards that held the alternate soundchips. Glad you like it! It was the first commercial drum machine to incorporate snares with built-in reverb. I also worked on the Kawai XD5 – the first to have a sub-woofer tone to beef up the kick.


  • Wow Osc.
    We’ve been reverse engineering your work and the work of your peers for years now!
    It’s really cool to have you aboard.
    I’ll bet you have some really interesting info to share!
    I’d be really curious to hear about the process of recording and encoding the samples.

  • Hi Osc and All,

    Question: How many ROMs were released for the R100? I have only located 3, but some people are saying they have a switcher that has 4 EPROM slots. Also, yes please post info on the encoding of the ROMs and save us all from reverse engineering this beast! ;-)

    I have looked at the fengland.org R100 stuff, but it seems buggy. And AnalogMonster mentioned AWave… anyone have experience with that doing R100 or lesser 8-bit ulaw drum machine work?


    PS. I have some switcher boards similar to the old Drumware ones for sale on my eBay page.

  • Just a quick followup. I think I found the bugs in fengland.orgs work and I can translate a .BIN file to .RAW or .WAV and theoretically back again. Still verifying.

    I was wondering if anyone had any insight on how I should go about taking (say) old Linn or Oberheim data and bring it forward to the R100. I think the sample rate on the old stuff is about 22kHz, whereas the R100 is 32kHz. Correct me if I’m wrong. How do I account for that? Is there are free editor that can do it (sample rate conversion)?

    Also, the Linn and OB EPROMs are 8-bit u-law which I think I can convert, but I’ve heard there are software packages that can read it directly and maybe convert it to 16-bit? Then I guess I can down-convert it to the 12-bit R100 format. Time will tell…


  • voxengo r8brain is free, that will do the sample rate conversion. Bit depth is a different matter, and this is why I gave up trying to sort custom roms. I have been looking for a program that will save as a 12 bit audio file – not Sony Soundforge, not Adobe Audition, Not Audacity. saving to 8, 16 or 24 is easy enough, the majority of software will do that.

    Awave can save wave files as Mu-law 8 bit, so presumably can open them too. Demo version lets you play with 1 file before having to reopen so its kind of free.

  • hmm, Grant B triggered my curiosity with the 8bit mu law stuff. Wikied the oberheim DMX and it states this:

    The data format is 8-bit PCM using ?-law companding, increasing sound resolution to approximately 12 bits in the analog domain (a design technique also employed by other early drum machines, including products by Linn Electronics, E-mu Systems and Sequential Circuits).

    So perhaps the kawai data is not stored as 12 bits, its possibly 8 bit mu law. Gives me something new to fiddle with!

  • Well, I’m still working on this when time permits. There is definitely something non-linear or non 1:1 going on, but it may be the ROM encoding/decoding and not the DAC. Not sure at this point, but if that’s the case it will be harder to sort out.

    References have been made here and elsewhere to a 12-bit DAT companding format for the DAC, BUT I don’t know if those are founded. I don’t see anything in the data sheet that implies companding (like in the u-law case of Linn/OB/360/Emu).

    My reading of the DAC312 data sheet and R100 schematic tells me it’s linear, single-ended 0 -> +15v centered around half way +7.5v). Now I will need to scope that and measure to make sure. Certainly there are the 100pF sample & holds to deal with because the DAC output is multiplexed (8 instrument outputs plus L/R). Finally each of the 10 outputs is turned to AC from single-ended and LPF applied.

    The other thing of note is that I’m pretty sure the sampling rate is 31,250 not 32,000 as stated in the manual.

  • I have concluded via experimentation that this whole RFC 3190 thing is a red herring. See my blog post at: http://musictechnologiesgroup.com/blog/?p=80 . It’s not terribly far off though, so maybe has some other similar algorithms they can suggest. For one thing DAT didn’t come out until after the R100. Did Kawai do something similar in their synths at the time?

  • I figured it out … kind of. I’m still working on the formula, but you can see the compression waveform that Kawai uses here:

  • The manual and software are here:

  • Why settle on Eprom extensions ?
    And why go through the pain of trying to buy
    I am going to design an extension that reads memory stick which You have saved the sound files right from Your PC.
    The interface card going inside the R-100 has a SRAM interfacing the Eprom socket. And of course a micro controller to move data from the stick into the RAM and do housekeeping on the SRAM data and address buses. The USB connector for the stick has to surface somewhere but that is the least of the issues…
    Since memory sticks can contain more than one eeprom image – in fact, there will be a way to switch between images. The interface for this might be IR remote control toavoid punching the R-100 or even RF interface. Remote controlled R-100 that is.
    The problem here is that the change is not instantaneous – it may take several seconds. This may be an issue. Hopefully not too bad.

    Wish us luck !

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