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[FIXED] MT-32 Control ROM upgrade in MT-100 breaks demo song play + v2.02 ROM dumped

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First post, by RichB93

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Hi all,

Just wondering if anyone had come across this or not? I recently got a Roland MT-100 which has a second generation MT-32 in the bottom of it as the sound module. My unit came with version 2.02 of the MT-32 Control ROM installed.

I had a look around online and saw that there is a newer v2.07 Control ROM available for the MT-32; admittedly I don't know what changes this ROM has, but nevertheless, upgrading to the latest ROM is usually not a bad idea.

Anyhow, burned a copy of the ROM, and I noticed that whilst the MT-100 still otherwise works fine (as does the MT-32), the demo tunes no longer play.

This is also the case for v2.04 and v2.06 MT-32 Control ROMs which are available online. None of them provide demo song playback.

I'm not quite sure how the MT-32 and PR-100 parts of the MT-100 interact with each other. From what I can see in the v2.02 Control ROM from my MT-100, the last half of the chip where MT-32 ROM demo songs reside is blanked out.

It's odd because the chip is marked as a MT-32 ROM, but it definitely has something slightly different for use in the MT-100.

I provide a dump of the v2.02 MT-32 control ROM from my MT-100 with this post as it is seemingly not yet dumped from what I can tell (some places online state that anything before v2.04 wasn't released!)

Cheers,
Rich

EDIT: This is all a load of rubbish. See this post: Re: MT-32 Control ROM upgrade in MT-100 breaks demo song play

Last edited by RichB93 on 2025-07-31, 22:18. Edited 3 times in total.

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Reply 1 of 4, by Cloudschatze

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Your v2.02 dump is missing half of the data. Assuming you're using a TL866 device, you'll need to use a non-JEDEC adapter to properly dump or write a v2.0x MT-32 ROM.

Reply 2 of 4, by RichB93

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Cloudschatze wrote on 2025-07-28, 22:35:

Your v2.02 dump is missing half of the data. Assuming you're using a TL866 device, you'll need to use a non-JEDEC adapter to properly dump or write a v2.0x MT-32 ROM.

Ah, that's another rabbit hole to go down - thanks for this!

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Reply 3 of 4, by RichB93

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Right, I've re-dumped this properly - didn't want to wait around for an adapter so I just lifted the pins and soldered wires to switch the pins. First post now has a proper dump of v2.02.

I burned v2.07 to a chip and with the wires switched confirmed that all was working as expected on my MT-100. Success!

I didn't really like the idea of having the jumper wires inside the MT-100 however, so I bravely stupidly wiped the original V2.02 ROM and started burning v2.07 onto the original UVPROM. Except that my TL866 really didn't enjoy programming it and kept throwing errors.

I was able to improve programming reliability by increasing the pulse time to 200ns as per the data sheet of the original chip. It still kept failing during programming, but less often. One bash loop later however and the chip did eventually program, and I verified it.

So I now have a v2.07 ROM in my MT-100. What an adventure.

Couple of notes:

  • If you don't care about the built in demos, you can seemingly use a non JEDEC chip like a 27C1001, as the first 64K contains the actual ROM and the last 64K contains the demos - so it will work, sans demos.
  • If you do want to use a 27C1001 in your MT-32, you can program the chip normally, lift pins 2 and 24, then solder the lifted pins to the points displayed in the image (image yoinked from another thread here). Effectively the OE pin is grounded, and A16 goes to a test point on the board just above the '64' silkscreen by IC35.

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Reply 4 of 4, by Cloudschatze

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RichB93 wrote on 2025-07-30, 14:55:

Right, I've re-dumped this properly - didn't want to wait around for an adapter so I just lifted the pins and soldered wires to switch the pins. First post now has a proper dump of v2.02.

I did something similar before purchasing an adapter. 😀

I'm glad that worked out, and thank-you for the re-dump of v2.02!

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