IIRC you need a 256kbytes rom so a 27C020 and variants will work fine

edit: yep 27C020 is the correct part - I used in the past some 27SF020 eeproms
look at the rom pic here: https://modelrail.otenko.com/retro/roland-sound-canvas-sc-55

keropi wrote:

IIRC you need a 256kbytes rom so a 27C020 and variants will work fine

edit: yep 27C020 is the correct part - I used in the past some 27SF020 eeproms
look at the rom pic here: https://modelrail.otenko.com/retro/roland-sound-canvas-sc-55

So you can dump and burn eproms then? I've a request over in the MT-200 thread where the the OP would like to get a hold of newer firmware for his MT-200 since both of the units I own have a version 2.0 and 2.01 firmware on them and his is apparently version 1.0.

I don't have an eprom programmer to do it myself but....

^ send me a PM with the the rom image and your address and I'll sort it out for you 😀

tpowell.ca wrote:

2.00+ loses support for Capital Tone Fallback but retains General Midi instruments.

The v2.00 SC-55s do support capital tone fallback. There is a slight difference in drum set Program Change behavior however, affecting the improperly-programmed sequences of at least two known game titles.

Do we know what other changes there have been between ROMs 1.20 and 1.21? What else did ROM 2.00 bring?

Apparently not all GS-only sc-55s are the same, some are GM

One of the bugs present in 1.20, and fixed in 1.21, relates to the processing of multiple, consecutive NRPN messages. This is only an issue where the playback of particular GS sequences is concerned. I can provide a recorded example demonstrating this bug, if there's any interest.

Cloudschatze wrote:

One of the bugs present in 1.20, and fixed in 1.21, relates to the processing of multiple, consecutive NRPN messages. This is only an issue where the playback of particular GS sequences is concerned. I can provide a recorded example demonstrating this bug, if there's any interest.

Hi, I recently just aquired a SC-55 1.20. How much does the bug effect on the DOS games? Would that be a problem on most games?

Should I be worry about it and look for a 1.21 instead?

I also got GS-only SC-55 with 1.20 ROM recently. I've found 27C020 for $1 shipped. Whats the cheapest programmer that I can use? I see some available on Aliexpress but i'm unsure which one to get. Also where can I find the 1.21 dump ROM file? Thanks!

ssdj wrote:

How much does the bug effect on the DOS games? Would that be a problem on most games?

No, since the bug is GS-related. In GM mode, this bug will never occur.

Slot1 you can get a TL866 programmer, affordable and will do many things - that's my go-to programmer for eproms etc
don't know of any cheaper that is still a good device

Thanks keropi, but I think TL866 is expensive for just one job. It is the same price I paid for the SC-55. 😁
What about those 3 or 4 dollar ones, like SP200S?

^ I can't see on that support list anything 27C020 related...
where are you located? EU or US?

Greece's Neighboring country 😀

allright will write one for you 😀

Wow, thank you very much, you are the best. 😀

I received the 1.21 ROM chip!

Removed the Toshiba battery, not really needed. Thankfully the board was not damaged from the battery leak.

Installed the new chip.

Works great! Thanks keropi!

excellent news! it arrived so fast !
enjoy!

Hello all,

I finally got a SC-55, the ROM is 1.10 (Firmware), the Roland chip is R15199775, is this one the control ROM?
According to this thread I can't upgrade the ROM firmware to v1.21 or 2.0?. The Roland chip is not on a socket and it will be a pain to remove it, not to mention finding the right one in the wild, I have no plans on doing that.
I have a programmer to upgrade the rom, but I guess I should NOT be using 1.2x or 2.x firmwares?, If so, how bad is version 1.10?? any concrete comparisons between mine and 1.2 and 2.0?

Dusko wrote on 2020-09-05, 06:04:

Hello all, […]
Show full quote

Hello all,

I finally got a SC-55, the ROM is 1.10 (Firmware), the Roland chip is R15199775, is this one the control ROM?
According to this thread I can't upgrade the ROM firmware to v1.21 or 2.0?. The Roland chip is not on a socket and it will be a pain to remove it, not to mention finding the right one in the wild, I have no plans on doing that.
I have a programmer to upgrade the rom, but I guess I should NOT be using 1.2x or 2.x firmwares?, If so, how bad is version 1.10?? any concrete comparisons between mine and 1.2 and 2.0?

Here's what I have pieced together:

Early SC-55's have an incorrect instrument mapping, #122 is 'Key Click' instead of 'Breath Noise'. Some Duke3D tracks use Breath Noise. This is an issue on units with firmware < 1.20. Which is at least all units that say 'GS Standard' instead of just 'GS' or 'GS/GM', but also some 'GS' units. Unfortunately it seems Descent wants the incorrect mapping.
Firmware 1.20/1.21 have the correct instrument mapping, and they run a GS reset instead of a GM reset (i.e. GM reset doesn't turn off GS features). Newer devices disable GS features on a GM reset, which can mess up some (Build Engine) games.
Firmware 2.0x and SC-55Mk2 units fix the reset issue. It seems GS/GM units always have 2.0x firmware, and some GS units do.
Mk2 units lose 'Capital Tone Fallback', which means an instrument's capital tone is used instead of a variation if that variation doesn't exist. Again, some games depend on this behavior.
Firmware 2.0x and Mk2 units play silence where some drums have a duplicate program change number on the earlier versions.

So for some games, your firmware version will result in incorrect behavior.

Hi Oetker, Thanks for your comments, I have a better picture now, I was so exited about this unit because it looks so brand new, doesn't have a scratch, it came with its original box! I'm still happy about it but with mixed feelings. The good thing is that I also own a mk2 so that'll cover for those games. Not exactly sure how accurate the sounds will be from the mk2 compared to an original SC-55 (assuming both have same midi "formats"). For example, I have a SC-88 Pro and while playing Shadowcaster noticed that the levels on some instruments are lower in the mix and it just didn't feel right, I needed to put some instrument levels up to get it right. Yes, I know I can just use the button for SC-55 mapping mode which did the trick, but I don't remember where I read that the SC-88 Pro in SC-55 mode is still not as exact as an original SC-55, don't know if this is true or not.
If the mk2 accurately covers the gap I have, I guess I'm good to go!
Again, I'm not supposed to use a firmware above 1.1x, correct? does anyone know this for a fact? Is there a version I can upgrade to between 1.10 - 1.19?

I'd say just enjoy the SC-55 it's a great unit
I actually prefer the old GS-only ones and it's the unit I power up in games even though I have a mk2
don't let small insignificant differences spoil your gaming 😉