TurboCPU v1.40 (beta) is available

A new version of the TurboCPU+MIDI firmware has been uploaded to the website, along with a new version of the Windows application TurboCPU.exe.

Added: “MIDI Note Priority” which supports 4 modes: Lowest Note, Highest Note, Last Note and my original mode (called One Note). There is a 10 note stack for Lowest, Highest and Last (the default is Last). The Last, High and Low Note priorities read the RETRIG switch live to determine whether a new envelope is triggered on subsequent MIDI keys down or not.



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MIDI Patch Change Editor v3.31

Ok folks, I have uploaded v3.31 of the PC editor for the MIDI Patch Changer. There are several bugfixes regarding Preset Navigation and the MIDI Events Editor. As well, by popular demand, a “Cancel” button has been added to the Midi Events Editor so that you can abandon your changes. Sorry that took so long. The web page and manual need updating a little, but the latest stuff is online at:

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MIDI Patch Changer: Set Patch Range Hack

Here is a relatively easy hack to let you change how the MPC keypad display MIDI Program Change numbers: as 1-to-128 or 0-to-127. This setting is made available as kind of a “hidden” feature. Hidden in the sense that you have to send a System Exclusive (Sys Ex) command to the keypad to turn it on and off.

Send any MIDI data

MIDI Program Changer/Controller

First of all, here is the manual description for the feature:

Set Patch Range

You can set the range for the Patch Change values to be 1-128 or 0-127.  Underneath, the firmware always transmits the hex values according to the MIDI Spec. (0x00 to 0x7F hex which is 0 to 127 decimal), but most MIDI gear uses 1 to 128 for patches.

NOTE: The editor/librarian only supports program change numbers 1 to 128.

You can send either one of these Sys Ex commands at any time. You don’t need to put the keypad in any special mode. To send a command you will need a utility program such as MIDIOX or SendsSX, or perhaps you can a way of sending Sys Ex from a Sequencer PC application.  Here are the commands:

  • F0 7D 22 22 09 00 00 F7
  • F0 7D 22 22 09 00 01 F7

The first is for range 0 to 127 and the second is for range 1 to 128.


Posted in MIDI Patch Changer | 1 Comment

A Plethora of DX7 Backlit LCDs

I had a chance to grab a bunch of LCD’s for the original Yamaha DX7 and picked up a variety of colors.  They are all really nice and look much better than my photography suggests.

LCD_BlackOnBlue LCD_BlackOnGreen LCD_BlackOnWhite LCD_GreenOnBlack LCD_GreenOnGreen LCD_WhiteOnBlue

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TurboCPU DAC/CV Option – New Parts Source?

I made an interesting discovery on the web today. There are a lot of companies making “Breakout Boards” and “SMT to DIP Adapters” but I’ve never found an assembled one for the MCP4728 DAC used in the TurboCPU’s CV/DAC option … until today!

From here:  http://www.proto-advantage.com

I just ordered one assembled breakout board (DAC chip and pins installed) as well as just a blank board with machine pins. I will test them both out. If it all works out then this is a good place to order these parts from because making the CV Option is a major bottleneck for me.

Here are the parts I ordered:


MCP4728 Breakout Board, chip included, assembled.


Part Number: PA0027-MCP4728, MCP4728 Breakout Board

MCP4728 DAC breakout board, unassembled, DAC not included.

MCP4728 DAC breakout board, unassembled, DAC not included.


Part Number: PA0027, unassembled with machine pins, ROUND.

A few things to note about this right up front. Since the beginning of 2014 I have added a second area on the TurboCPU’s MIDI board to put the DAC chip on. The original area is the tiny MSOP-10 footprint, the new area is a 10-pin DIP footprint.

MIDI board showing both DAC locations (in red)

This has allowed me to order MSOP-10 to DIP adapter boards… which makes assembly a bit easier.  To date I’ve been using adapters from




but this new discovery from Proto-Advantage is very exciting! Now, because I’ve also been installing a 10-pin DIP socket I think the round machine pins are the better way to go as I’ve never really liked the idea of jamming square wire-wrap pins into a DIP socket.

The other alternative is for me to leave off the DIP socket and just allow you to solder the Proto-Advantage fully assembled breakout board right on the PCB. Once I get these and test them out I’ll decide which route to go.

Posted in Pro One CPU | 2 Comments

Time for Kidney Transplant

Hey kids,

I’m getting a new kidney.  Wish me luck!  Soldering and programming to resume as soon as I’m able, but I imagine that’s at least a few months away.


Posted in Kidney Transplant | 3 Comments

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.



Posted in MIDI Patch Changer | 5 Comments

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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