Author Archives: grantb4

6809 & 68HC11 Monitors, Assemblers, C Compilers, RTOS … from the 90s

I retrieved some old embedded fun I had in the 90’s off an old disk. More to come at some point once I find the other disk.  Anyway this is a recreation of an old website I had. Retro fun. … Continue reading

Posted in Motorola 6809 68HC11 | 1 Comment

TurboCPU MIDI Board – Alternate Source

If you are in the UK or EU (ouch), here is a source for a DIY MIDI IN/OUT/THRU bare PCB that can be used with the TurboCPU. No DAC option, but otherwise it’s pretty similar to the MTG MIDI board. … Continue reading

Posted in Pro One CPU | Leave a comment

Found Another DX7 Bug

This one isn’t a huge bug, but anyone with an original DX7 running OS version 1.7 or earlier (on an expander based on it) can see this bug.  If you edit a patch and set an oscillator mode for Fixed … Continue reading

Posted in Yamaha DX7 | 1 Comment

MIDI Velocity Tester

While looking into the DX7 and some of the expansions for it, I needed a way to capture all the possible velocities that a given MIDI keyboard could put out. Not all of them send all 127 possible velocities. I … Continue reading

Posted in Uncategorized, Yamaha DX7 | Leave a comment

DX7 Velocity Issues

A lot of comments, cliche’s, criticisms and chit-chat exists about the original DX7 Velocity limitations.  I will address a few of those, mainly from the perspective of someone looking at the underlying code. It’s another level of fun for someone … Continue reading

Posted in Yamaha DX7 | Leave a comment

Yamaha DX7 OS without Active Sensing

While peeking around at the various DX7 firmware versions I was able to identify the code that is responsible for the DX7 transmitting $FE (MIDI Active Sensing) constantly.  I did not have the time to look at adding a menu … Continue reading

Posted in Yamaha DX7 | 1 Comment

Hitachi HD6303 Monitor

The Hitachi 6303 is a variation on the Motorola MC6800/6801/6803 Motorola microprocessors and microcontrollers from the late 70’s and early 80’s.  I have an interest in reverse engineering embedded systems from that era.  Previously I have created a 6809 EPROM … Continue reading

Posted in Hitachi HD6303, Yamaha DX7 | 6 Comments

New MTG Kawai R-50/R-50e to R50iii conversion kit

This is a kit loosely based on the R50iii that was a factory modified/upgraded R50 or R50e.  The factory had the advantage of starting with new blank circuit boards which current R50 owners do not.  Still, this expansion is pretty … Continue reading

Posted in Kawai R100 | Tagged , , , , , , , | 1 Comment

A DX7 Expansion “for the rest of us”

The DX7 E! expansion is known for being very hard to use. The SuperMAX+ is easier, but still there are so many features that it can be hard to remember them all, … and not everyone needs them.  So I’m … Continue reading

Posted in Yamaha DX7 | Tagged , | 14 Comments

CR2032 Battery Holder PCB Saver Adapter (for DX7, etc)

Here is a quick “freebie” of sorts. I’ve had this PCB for a while and used them now and then to fix dead 3v coin cell batteries on Yamaha DX7’s and other synth’s and drum machines. You can order the … Continue reading

Posted in Uncategorized, Yamaha DX7 | Tagged , , , | 1 Comment