Pro One TurboCPU v1.32 – Again with the updates

Further refinements to both the firmware and PC software. The main changes are in the firmware and they are:

  • When the Sequencer is driven by the MIDI clock with Seq Tie Disabled, the gate time is now 50%. Previously it was far too short. This is a bugfix.
  • There are no longer any communications with the DAC unless there is a voltage that needs updating. This reduces digital traffic on the I2C lines and reduces the CPU burden as well.
  • Added waveform #11 called “Drum” to LFO2. When used in conjunction with KeySync ON, provides a single downward ramp per note played. Perfect for resonant feedback style drum synth sounds.
  • Added a SysEx command to reset the synth to Factory Defaults.

The last two items are also supported in the software. For now these are available by request only. I will put them on the web site when I get time.


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MTG TurboCPU+MIDI+CV v1.30 Beta Firmware and PC Software Available

I’m just finishing up the v1.30 firmware and a basic PC editor for the TurboCPU. This version will not be the shipping version for a while yet, but you can get your hands on in now if you are interested.  The main feature for the CPU firmware is support for receiving MIDI Note-On VELOCITY.  So at the moment there are now 5 sources of MIDI data in the CV code:

  • Pitch Bend Wheel
  • Modulation Wheel/LFO2 (LFO2 is a second LFO done in the firmware)
  • Manual CC 1
  • Manual CC 2
  • Note-On Velocity

You can pick up to three sources at a time and assign them to these destinations:

  • DAC1: OSC1/OSC2 Frequency (default is to send pitch bend data here)
  • DAC 2: VCF Cutoff (default is to send mod wheel to LFO2 to here)
  • DAC 3: VCF Resonance (default is to assign this to a manual continuous controller)

The latest User Manual has been updated to reflect the changes. EMAIL ME for copies of the firmware, manual and software.

SCI Pro One Editor

TurboCPU Editor CV Panel

Also you can update the firmware using this application which is probably easier than MIDIOX. There is an earlier blog post describing the editor software in greater detail


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MIDI Patch Changer Keypad – updates

Send any MIDI data

MIDI Program Changer/Controller

There have been several major updates to the software and firmware for the MPC keypad over the past year. This latest software update (v3.22) fixes a minor bug you might encounter when using the Pre- or Post- Program Change arbitrary MIDI data.  The current firmware is v3.20.

Check out the keypad page to download the latest software.


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TurboCPU – Updates and Software

It’s been about two years since I touched the TurboCPU code.  I should have v1.20 ready soon.

Here is what I have fixed so far:

  • The envelope was not retriggering when you lifted one of two keys held down when RETRIG switch up. I fixed this so that the TurbopCPU behaves like the original in this regard.
  • Downloading SEQ2 over MIDI would mess up SEQ1. This has also been fixed.

I will look at a few more things before I button this release up and post it on the web.

In other news, I thought I should release the Windows “editor” software I use for testing and working with the TurboCPU+MIDI. It allows one to change any setting instead of having to use the power-on keyboard method, so much nicer in that regard. It also allows you to manage sequences over Sys Ex. I’m going to try and add firmware updating to it before I post it. The CV/DAC part isn’t finished yet but I will add that as time permits. Here’s a look at what I have so far. Email me if you want to try it.




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MTG R100 Builder – Kawai R100/R50 EPROM Builder Software

This software will enable you to create your own custom EPROMs (BIN files) for the Kawai R100 or R50/R50e legendary 12-bit drum machine/rhythm composers.

In a nutshell you collect/create a bunch of WAV files, one for each of the 24 instruments and then this software compiles and converts them into the compressed Kawai format. It’s been a pretty big undertaking, starting with the dissection of the Kawai ASICs.  I will eventually include a User Manual and a bunch of WAV and BIN files to get you started.

Your WAV files should each be:

  • Mono (1 track)
  • Sample rate of 31.25kHz (you can resample easily in Audacity or similar)
  • 16-bit linear PCM (standard WAV)
  • Should fit within the sample space of the pad you are targeting.

Kawai R100 Builder

The look and feel of the software is based on the HR16 Editor by Dustin Licis. You can save file sets as a project to save time in the future.

Why bend and mutilate a fine instrument when you can bit-crush samples and add them to your kit?

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Kawai R100 DGU Compression Exposed

Just a quick note to say that I have made some progress with the Kawai R100 12-bit compression encoding. What Kawai are doing here, near as I can tell, is storing the sound data in logarithmic format. This allows them to perform mixing and volume control in the DGU ASIC using addition, rather than multiplication. Thanks to the fine people on Synth-DIY for mentioning this posssibility.

I hooked the EPROM data lines and the DAC data lines up to a logic analyzer and captured an output (DAC) value for every possible input value.  Needless to say it was a lengthy and painful process.

Here is the preliminary result. I have yet to create a proper look-up table (or transfer function), but this is a good start.

Kawai R100 DGU ASIC

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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 SRAM  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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Kawai R100 Soundswitcher board by Drumware Inc.

Here are some photos of the ROM switcher board in my Kawai R-100 Drum machine. The expansion board is dated 1987. My unit contains three 4Mbit mask ROMs:

MN234000KAA, MN234000KAB, MN234000KAC

I think these ROMs are the original R100 and R50 and the R50e judging by what I’ve read elsewhere on the web.  The sound format is 12-bit (non-linear) with a 32kHz sample rate.

P1030550 P1030548 P1030570


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Yamaha DX7 SuperMAX is in!



Great expansion and feature upgrade for the beloved DX7.

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NEW Keyboard for SCI Pro One!

A long time ago I ordered a new 37-key Doepfer keybed and cable from in the USA. In fact I think Doepfer gets them from in Europe so there might be a better way to obtain one. The new keybed is make/break (velocity sensitive) style, but the Pro One does not have the pinning to make use of the break contacts, so I only used the make ones.

Long story short, after making a new cable out of the supplied Doepfer/Fatar one and a 16-pin DIP, my Pro One keyboard is like brand new! The new keybed will fit in the Pro One, but the hole pattern on the bottom of the synth need to be drilled. This is fantastic news for anyone that has the membrane style Pro One keyboard. Anyway it will work with either the original Pro One CPU or my new TurboCPU. I have a couple of photos, but will also upload a wiring pinout later when I get time.

SCI Pro One new keyboard

pinout for the Fatar 37-key matrix to the Pro one DIP connector

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