Yamaha C1 – the Kraftwerk-computer

Yamaha C1 – a beautiful piece of hardware and a nightmare

“Dear people of the future: Here’s what we found out so far”

The computer itself

Some time ago, I aquired a Yamaha C1 “Music Computer”. It seemed to be a quite beautiful piece of hardware.



I used to say that it has a dozen of MIDI-Ports, but I was wrong. It only has eleven.


At first, one might ask who might ever need eleven MIDI ports. If you’re not familiar with MDI, you might even wondert who might ever need one. It makes sense for musicians: If you have several MIDI instruments and synthesizers, you might want a port for each of them. This is why the computer is called “Music Computer”.



It can really help musicians to record their music, play them back, use a sequencer… Fun thing is: With only an 80286 processor and less than 1.5MB of RAM, you wouldn’t expect it to be powerful enough for music. I believe it is not powerful enough to produce music, but it’s more than capable of handling the signals. If this seems like a contradiction to you, you might want to read up on MIDI.

But MIDI signals are not only user for playing music. They can handle all kinds of other signals as well. The german music group “Kraftwerk” used this computer to control the robots they had on stage. Yes; those weren’t people in simple costumes (like the ones we used in school plays when we were young), those were actual robots, reacting on signals by moving their motors.

Note that I didn’t say “used one of there”. I said “used this computer”. When the hard disc still was working, I was able to copy sequencer and some of the movement data.

As you might have guessed, it doesn’t work any more. Still I’d have loved to use this computer for anything (especially once I learned more about MIDI) and wanted to repair it. That’s when I found the Yamaha C1 to be a complete nightmare.

Opening Up

Opening it up wasn’t too hard. Of course, I needed to keep track of the different screws. The upper part of the computer (keyboard and display) was connected with only a single plug.


The floppy disc had the standard 34-pin-connector (or so it seemed at first), but then the hard disc turned out to be quite a surprise: It’s connector has 26 pins. There is no Molex power plug. The one in the picture is for the floppy drive.



At the point, regular PATA could be rules out. Still I hoped that this might be regular IDE or even SCSI with just a strange pinout. After I found the controller card, the strongest guess was MFN – well, not my guess but that of people who know more about this stuff than I do. This was also fueled by googling one of the chips and finding a post from someone trying MFN.


Another strange thing about this controller card was it’s connection to the main board. It is no standard ISA slot – our strongest guess is that it’s ISA on a pin connector – together with power.


At that point, I started giving up on the idea of changing the HD. The other guys suggesting finding out the pinout of the connector and then building a converter to regular ISA – and then connecting a regular IDE HD. Or I could solder my own ISA-IDE-card for those connector pins. All of this seemed beyond my capabilities so I gave up on that idea.


By the way: The BIOS doesn’t allow setting cylinder count HD heads or so – and don’t even think about “auto-detection”. It only supports the original types whose information was hard-coded into the BIOS.A long time ago, there were just 46 “standards” for cylinder count, heads, etc. Later BIOS had “Type 47” which was “user defined” (so you could at least copy the data from the disc sticker). Even more modern BIOS allowed you to auto-detect the information from the HD and insert the data into the Type-47-fields. Nowadays, of course, auto-detection is the most common way.

Anecdote: A colleague once reported to me that he ran into that problem when replacing/updating a HD and he solved it by reading the BIOS from the EPROM; patching the BIOS and then flashing it to an EEPROM. This obviously requires some EPROM reading and flashing hardware. For the Yamaha C1 this could become a possible path once other HDs can be connected.

According to some old manual, “with hard disc” was only on of the flavours you could get the Yamaha C1 with. Another was “two floppies”. Judging from the BIOS, the 20MB-disc drive is “Type 2”.



Plan “Revive from Disc”

After the “replace HD”-idea was pushed back, I thought about booting the computer from floppy. Yes, dear kids. A long time ago, computers could be booted from floppy disc and didn’t need hard discs, CDs, DVDs or USB-Storage-sticks. A long time ago, computers didn’t even have this luxury and everything was done on discs. And even that was a gratitious update to the times before (google “punch card” if you dare).

I planned on emulating the hard disk via interlnk and a parallel laplink-cable. For the younger ones: “laplink” is a tool for data transfer via the parallel port. Most often, the printer was connected to that parallel port (long before everything was USB). You connected two computers via a special cable (crossover) and then could copy files much faster as if you’d have to write and read them from disk every time.

Interlnk/intersrv is a software-dua included in MS Dos 6.22 (or so) which allows to setup one PC as server and then pretend on the client-PC that the data from the other side comes from a hard disk. It even get’s a device letter.

From what I’ve been told, Dos6.22 should be able to boot even on older hardware, so I tried a DOS6.22 boot disk. My first try failed as I forgot that the Yamaha has 720KB disk drives instead of 1.44MB ones (don’t get me started on 2.88MBB). Still, even when formatting a DD-Disc as bootdisc, the Yamaha refused to boot from it.

Okay, I thought to myself, The computer is old. Maybe the floppy drive is broken, too. I tried replacing it with functional one. Thankfully the BIOS supported 1.44MB disk drives.

At the point, I found another interesting (disturbing) thing: The floppy cable was wrong. Normally, when PIN1 (the marked wire) is left, the connector has the budge on the top. The cable in the Yamaha has the regular budge on the motherboard-side but not at the floppy side. Still, you won’t realize it as the floppy itself has the same orientation. Yet, as soon as you try to connect a regular floppy or try to connect the Yamaha-floppy with a regular cable, you recognize that something is wrong. The floppy light is on, permanently.

So after some careful pushing, I was able to connect this floppy to another computer but it didn’t work. It didn’t work the same way as a regular floppy drive didn’t work at the Yamaha. Later on, I found out the the FDD-cable has another strange twist:

You might know that it is posible to connect two floppy disk drives to a standard FDD-Bus – but how does the computer know which one is a: and which one is b:? Mordern SATA hard discs each have their own cable, on PATA hard discs, you have “Master/Slave”-jumpers (or even “slave present” on even older ones), but floppy disk drives have no such jumpers.

The solution is as strange as it is simple: At some point in the FDD cable, seven wires are crossed. A drive after this cross will be a:, a drive before this cross will be b:

The cable in the Yamaha computer has two wires crossed. So it seems incompatible with everything except itself. I guess that the Yamaha floppy even depends on this strange cable so it’s no wonder it didn’t work on another cable.

Still, it didn’t even work as b: (uncrossed part of the cable) and it even prevented a regular a:-drive from working when it was connected.

The Yamaha reported “No Boot device available”. It didn’t report errors with the disk drive (except when I selected it for the wrong type or primary/secondary). It seemed like the computer really insisted on booting from hard disk – which I considered strange as it should also be able to work with two disk drived. Did it somehow know that it was the HD version and wanted to boot only from HD? Wouldn’t that make it impossible to reformat the HD?

Everything was strange about this computer: it’s BIOS, it’s hard disc controller, it’s floppy disk. Ant with a defect hard disk and a non-booting floppy drive and the impossibility to connect a regular floppy my chances of ever working with the computer looked pretty slim.



This is the point when I started this text. This is the point when I believed everything to be lost and just wanted to record my experience and share the photos I made.




Fortunately, Skern insisted on listening to the hard disk starting up – so I reconnected the controller card and hard disc and switched on the computer. BIOS reported hard drive fail, but no drive seek error for the floppy. Skern listened to the hard disc and said that it sounded rather okay.

And suddenly the computer showed the “DOS 6.22”-test and a prompt. It booted! It only needed the defect hard disk to be connected and set in BIOS and it decided to check the floppy for bootable medium, again.

At the moment, our strongest guess is that the hard disc controller is more than this: It also includes the floppy controller. Without it, the BIOS somehow recognizes the floppy drive but cannot access it as a bootable medium.

This is very “un-intiutive” as the floppy is not connected to the controller card – only the hard disk is (inclusing it’s power supply). So wires for the floppy go through the motherboard-connector into the controller card – and out again.

The next step is expanding the “plain” boot disk (only including command.com) to something usable (fdisk, format) and checking whether the hard disc really is lost. Skern said that chances aren’t bad that it will work again. Testing the computer with a floppy might also yield interesting results. Booting without HD but with controller could prove the floppy-controller-theory. However, it wasn’t ruled out that the computer needs a hard disk drive (even if it’s defect) to accept floppy boots.


After later experiments (post 2011-12-14)

The computer needs the controller card but doesn’t need the hard disk. I haven’t tried connecting a standard 1.44MB drive as b: – I’d need another power connector or would have to split the old one. I also doubt it would work. It wasn’t recognized as a: with the Yamaha cable (the same cable that didn’t make the Yamaha floppy available to a regular PC). I also didn’t try the Yamaha controller with a standard cable and a standard floppy. Once the Yamaha floppy successfully booted from disk, I decided I’ve had the computer open long enough and built it back together again.


Also, the hard disk drive surprised me for a moment: I had no floppy disk inserted and the computer still decided to boot up. For a moment I was able to access the hard disk. It was just for a moment – once I tried to access a database (finances? mails?), it was dead again. It managed to play alive several times afterwards (seems like the cold atmosphere really helps) but never for long.



Back to the original plan

As planned, I connected the Yamaha to another PC via parallel laplink-cable and one I started intersvr there, I could access the host disk drive (I booted from floppy and had no HD at the moment). Running the sequencer tools from floppy proved very unsuccessul – many read errors (although the disk was fine). Still, I managed to get miditest to work and connected the MIDI-ports with a midi cable as requested. After both MIDI-Ins and most of the Outs tested successfully, I decided that no problems should be expected, there.

To fix the problem with read errors, I connected an HD to the “regular” PC (host/server), formatted it with DOS, copied intersvr and the spg sequencer and from then on booted from HD (okay, I forgot one fdisk /MBR to get rid of an old LILA, but this was just two more boots).

I booted the Yamaha with interlnk, again, and served the software with the regular PC. Finally, I could start the sequencer (and MIDI-driver) on the Yamaha.

Unfortunately, I then was hopelessly lost in the software. I hoped that the Yamaha might at least give some beeps over the internal speaker. I hoped to get some response by connecting a MIDI-keyboard to an IN-port and pressing “record” in the software but I had to face that this software would need some more reading.

Fortunately, the manual for it can be downloaded from the internet. SPG is short for “Sequencer Plus Gold” which was programmed by a company named Voyetra. I found the manual on the homepage of turtlebeach.

Unfortunately, that was about the time that the universe deciding hating me. The Yamaha already had some freezed and I didn’t think much about it. But when I loaded one of the song-files (robopop.sng), the graphics screwed up. After a reset I only got a blank screen with two lines. Other reboots resulted in a completely blank screen and also the status LEDs indicate that there are larger problems than just the display. I guess that the graphics chips finally decided to go byebye.

Giving up, finally

So after I took the computer apart; tried a lot of things about the floppy; learned about the controller and even got suggestions to convert a regular controller; after I finally get a DOS to boot and established the connection to another PC in orhder to access the tools and data; just as I got the software to work with the hardware and only needed to learn how to really use the software, the Yamaha dies on my.

I may be wrong – I was wrong about the hard disk and it shows some signs of life. I may try to start up the Yamaha, again, and perhaps it will live, again, but for the time being, I’d like to move to other projects.


19 thoughts on “Yamaha C1 – the Kraftwerk-computer

    • I’m sorry, I found none of this sort. It might have been a lot easier to repair the computer or to find out how it works but as this is very old hardware, information is rather spare.

      • Do you remember the part number for the hard disk, is it a JVC one?
        If I was a clever programmer/designer I don’t think it would take much to make an MFM Hard Drive to CF Card system. There are things like that out there on the internet. Unfortunately I’m not clever. I wonder if it would be possible to set up a RAMdrive section in the memory and use a lithium battery to keep the DOS intact. Probably memory is refreshed on start-up so some change would need to happen to the system so that this section isn’t overwritten? I don’t really understand any of this 🙂

  1. Do you still have your C1? I have a C1/20 with also a bad drive but have an external HD that works. I also picked up a perfect at the time C1 with two floppies. I haven’t tried them in 10 years and they won’t boot. I have the service manuals as well as programming manual. Let me know if you want them. The programming guide is only good for software development but the service manual is best for repairing. I bought it a long time ago when I was interested in making an adapter to enable use of ISA devices on my computer.


    • It is kind of next door because someone else wanted to try working on it but I can still access it if I ask (kind of a group).
      I am very interested in these manuals and even if I don’t re-activate this project, soon, I would like to forward them to the others in our group so they maybe can use them.

      How is the external HD connected to the C1? If we could convert another HD for external use, the non-booting floppies might not be so bad and even the broken internal HD would be no issue.



  2. Hi, I’ve got a C1/20 in similar shape to yours, do you have the original disks and can possibly create disk images? The original SPG software that came with the C1 was specially modified to work with the extra MIDI ports and I haven’t been able to test the version offered on the Turtle Beach site, plus the other C1 specific software (MIDI Monitor, bulk dump, etc).

    I hit the point where you ran into issues with the floppy drive, but thanks to ebay I was able to purchase a floppy drive of the exact same make and model (down to the variant) as the one that’s already in my C1 to replace the non-functional hard drive. Mysteriously, it won’t boot even with two of the exact same floppy drives, although I have been able to boot it from floppy fine with the HD plugged in. I haven’t bothered to open it back up again to re-install the hard drive after the last attempt with the dual FD setup, mostly because it’s a tremendous pain to tear it down.

    About two months ago, someone was selling a C1 service manual on ebay, but I didn’t think to purchase it in time. Since the people on ebay who sell manuals usually just print out PDFs, with luck there is a copy of the service manual floating around out there somewhere. If I see it again I’ll be buying it and re-scanning it to distribute online.

    My original plan for a hard drive replacement was to set up an old Syquest 135mb parallel cartridge HD on the system, but I haven’t gotten around to it yet. There does exist a parallel zip drive driver which apparently works on 286 systems, but I tend to trust the cartridge HDs more than Zip drives simply because they’re older and tend to be more reliable.

    • I’m sorry. I don’t have the original disks; the computer rather was submitted “as is”. I think I’m lucky that the power supply was provided.

      I’m not sure whether the SPG-Software really was modified. I think that there is some driver that has to be loaded before the software can access the MIDI-ports but I’m not sure about that.

      I agree with you on the “tremendous pain to tear it down”. Did you remember that the controller card is needed for disk access even when no HD is connected?

      I’ve mostly given up on this project but I may still have the SPG-software (with driver) somewhere and could send it once I find it.

  3. Hello, I just got a Yamaha C1 that has an issue where the dip switch on the back being set for internal or external monitor has no effect, the LED is always on for “EXTERNAL MONITOR.” I don’t have an external CGA monitor yet (I’m going to make an adapter cable to go CGA to VGA to see if any LCDs will sync up.) Do you know if there are settings in the BIOS to override the dip switch on the back for internal/external monitor? I’m hoping this is the case.

    I found the trace on the PCB that goes to the dip switch 1 and did verify that in the on position it’s grounded, in off it has 508 ohms of resistance or something. So it’s not a case of oxidation on the dip switch.

    For the hard drive add on, you have to change dip switches under the keyboard to enable it. Without the hard drive card, under keyboard dip switch #1 up up, 2/3/4 down. With the hdd adapter added 1 down, 2 up, 3/4 down.

    I got the programming documentation and floppies with mine, I plan to scan it all and put it online.

  4. Hello I posted earlier, a bit more info. I have put the floppies and dumps of my BIOS chips online (link below.)

    I am looking for a copy of the BIOS EPROMs to compare. Is anyone with a working machine willing to run a DOS program that will dump the BIOS data to a file and email it to me? I think it might be imperative to archive this information because I think the machines might be coming to the age of bit rot with the programmable chips. The dump utility in theory would capture the data from 2 of the 3 EPROMs on the motherboard. Email me and I’ll dig up a link to the software.

    Also, I was looking at the technical documentation (I have tech docs on it, no schematics) and noticed the expansion connector appears to have all needed pins from the address, data and control bus. So I think it might be possible to reformat the XT-IDE controllre project to fit the C1 and give it a SD based hard drive.

    If anyone could do this — my email is ethan followed by @ then 757 dot org.

    Here is the link to my data dump:

    • Wow, thanks a ton Ethan. I’ve still got my C1 here and I’ve held on to the hard drive in the (likely vain) hope that I can resurrect the system eventually. Other projects have come up since then, but I’m subscribed to this comment thread so I’ll keep an eye in and post if I get my fingers back into the guts of my C1. Definitely post an update if you make any headway with an SD adapter, that would breathe limitless possibilities into a piece of hardware as potentially powerful as the C1.

    • I needed the interlnk to work and from what I remember, those were not available in earlier msdos versions. I also remember that the computer had no problems booting the modern dos.

  5. re: the comment that the original software was modified to work with the c1.. from what i read it was not modified in anyway.. except that it requires that you run the CAPI driver BEFORE launching the SPG app. the CAPI driver (which is used for the C1 instead of the VAPI driver tha tis normally used on a normal ISA based computer) is not included in the version of SPG that is posted publicly by Turtlebeach which is version 4.10 (NOT the final version)

    since i dont have a yamaha C1 im using a 386DX40 computer – im trying to find the original installer disks of voyetra sequencer plus gold v4.11 as this version was updated to allow using more than one MIDI interface on DOS/ISA based computers… i have bought a number of MIDI interfaces and i really need to find this version 4.11 installer which i believe has more drivers in its installer that arent available from turtlebeach publicly as of right now.. SAPI*.* drivers. basically the way the drivers work is that you first load a VAPI/TAPI driver and then afterwards u can load other SAPI drivers and assign them to specific ports following those of the initial device that had the VAPI driver loaded.. im doing this to get 4 or more midi ports out of the sequencer app.. version 4.11 holds the key to me getting this many ports working with multiple interface cards.

    if anyone can help me find these installer disks id really appreciate it. having put too much effort in to give up at this point. http://www.oldschooldaw.com/forums/index.php?topic=2368

  6. I recently found the service manual for this! (I dont own a C1, though I’m certainly looking for one). Will scan it for anyone interested! Ethan thanks for sharing that software, preservation is so important these days for old system media.

  7. Thank you very much. I was able to play the standard MIDI file (*. mid), which is the standard for midi file by “cakewalk 5.0”, while testing the Yamaha C1 I had.

    You can check the following URL video link :

    However, we have not seen a simple play program that plays a large number of mid-file files sequentially. Please let me know if you know a program that allows you to play a lot of standard MIDI files in Yamaha C1. Thank you.

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