Loading MSX DX7 Editor using MicroWaver WAV File

Recently I acquired a used MSX Yamaha YIS503II Home Personal Computer with several cartridges and a YK-20 keyboard. I posted an earlier article about the find. One thing that was missing with the package was the Yamaha DX7 MSX Editor, specifically the YRM-103 DX7 Voicing Program. My system also did not come with the MSX Floppy Drive system, however it did have the ability to transfer data using cassette tape. I did some research and discovered that it was possible to acquire the Yamaha cartridges in ROM format. I then found out it was possible to convert those ROM files to WAV format using a program called MicroWaver. I also used another that worked called Caslink2, however MicroWaver was the only program I could successfully convert to a higher bps rate that actually worked. A higher bps rate means a faster rate of transfer.

In the video you’ll see that on my MacBook Air I have a YRM-103 DX7 WAV file opened in Audacity. On my MSX computer I typed the command BLOAD”CAS:”,R and hit enter. I then played back the WAV file. You’ll notice that the MSX responds with LOADING and after about 15 seconds it loads up the YRM-103 DX7 Voicing Program beautifully. My MSX YAMAHA YIS50II has both the SFG-05 FM Sound Synthesizer Unit II module installed which includes both audio and MIDI in/out ports. I successfully was able to connect my Yamaha DX-7 and both edit and transfer data. Cool!

I now have one last potentially major problem to solve. I desperately want to use the DMS1 Mk2 MIDI Recorder for SFG-05 and do have the ROM file for it. However, when I convert it to WAV format it will get recognized and transfer appropriately with my setup, BUT my MSX then reboots at the end of the process. This reboot effectively clears the RAM memory and leaves me with an OK prompt. There is no start command for the DMS1 mk2 program so something either in the original ROM file or something I’m doing incorrect is causing it to not load. I’ve doing a couple of days of intensive testing and research and have come to the following conclusion. The ROM files were intended for Emulator use primarily and not for the use of REAL MSX machines. What I’m doing is out of the ordinary and perhaps not possible. I would love to have the DMS1 mk2 sequencer program working to create some of those old school 80’s tracks. I’m just not sure why the MSX is rebooting on it’s own. I used the blueMSX Emulator and the DMS1 ROM file worked great.

I also noticed that ROM files that contain a “Part 1” and “Part 2”, which is what I presume are two disks, don’t transfer well if at all via WAV format. The MSX Computer recognizes both parts, will load them, however the MSX computer YIS503II will ALWAYS reset or reboot after transfer completion. Again this results in memory being cleared and thus the program is gone. There is something about transferring multiple disks or parts that does not work via the PC WAV method so far. If I have a file with only one disk or part, it works great as with the YRM-103 DX7 ROM file above. It’s only one part and thus loads fine. If I can get the DMS1 to load than I would be set being able to work with the built in 4-OP SFG-05 and the Yamaha DX-7. That would be pretty cool and quite retro considering all of this is 1983-1986 stuff.

I’ll update this article in the comments section as I do more testing and discover more info.

DMS1 Mk2 MIDI RECORDER
DMS1 Mk2 MIDI RECORDER
Yamaha YIS503II MSX1 with SFG-05
Yamaha YIS503II MSX1 with SFG-05
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