I believe you can drive the SC-55 through the LAPC-I, but you need an external adapter of some sort. That would allow you running the GUS and LAPC-I with no resources conflicts whatsoever!

If you have the breakout box for the LAPC-I then use this to drive your external modules and disable the GUS mpu-401 port completely.
The LAPC-I is basically a MPU-401 + CM-32L in one card (just like the SCC-1 is mpu+sc-55) and it's onboard MPU is a fully roland featured one with intelligent mode and all the groovy things old games like 🤣

That's the trouble... I don't have MCB-1 for LAPC-I and it's a tough thing to find one nowadays. Otherwise my LAPC-I would be ideal for SC-55 for obvious reasons. It's frustrating that LAPC-I requires specific kind of MIDI breakout box in order to work!

I think if you want to use Roland, use Roland. As in, use a LAPC-1 or a real Roland MPU-401 interface to one of their synth boxes (I don't think any Sound Blasters are fully MPU-401 compatible either, at least not in intelligent mode. Most sound cards aren't, and only work in UART mode. Afaik the GUS does that just as well as any SB).
GUS Extreme is a great card if you want all-in-one, but that means you'd use MegaEm to emulate MT-32/Sound Canvas. Which works well, but you seem to want to use the real thing.

Yup. I was thinking on using GUS Extreme for GUS/SB and really hoping it would cope with SC-55 in "un"intelligent MPU-401 mode. But in another thread here on Vogons someone mentioned that GUS cards might require specific MIDI adapter to work, too (a bit like LAPC-I and MCB-1).

LA synth through LAPC-I, everything else through GUS Extreme. It would have been a nice all-around solution. But I guess I'll have to hunt down either MPU-401, MCB-1 or swap that GUS to another sound card altogehter. After all GUS sounds are just a bonus for me, I enjoy hardware accelerated Roland MIDI above all.

I have bought a genuine LAPC-I service manual, I'll go see if it covers the breakout box, maybe one can build a simpler version with only the midi-out ports and omit the metronome/tape controls

The GUS Extreme has an ES1688 onboard, right? AFAIK that chip has a true MPU-401 interface, and if that is what the card exposes, should work great for anything GM, no?

yes, it will work just fine for UART stuff unless the GUS does something strange with the ESS chip. Basically every new GM/GS game won't have a problem.

Here is the MCB-1 schematic , it seems that if you only want the 2x MIDI-OUT ports it's pretty straight forward, only a 74LS05 hex inverter along with some resistors are needed.

keropi wrote:

Here is the MCB-1 schematic , it seems that if you only want the 2x MIDI-OUT ports it's pretty straight forward, only a 74LS05 h […]
Show full quote

Here is the MCB-1 schematic , it seems that if you only want the 2x MIDI-OUT ports it's pretty straight forward, only a 74LS05 hex inverter along with some resistors are needed.

Hmmm. I think I'm going to try to configure my GUS Extreme first as jack-of-all-trades card this weekend. Not the easiest task but given how hard it is nowadays to come by with MPU-401 related hardware it's the quickest route to test. If I can get the ESS chip's MPU-401 and SoftMPU working with SC-55 I'm happy with the result.

But just for the sake of tinkering: Do you think I could safely ignore all the other connections (JK1, JK4-7) of MCB-1 diagram and just solder simple MIDI OUT box to use for connecting external modules like SC-55 to LAPC-I's MPU-401 unit? Won't LAPC-I mind if all other pins in the DB15 adapter are empty? I can get materials & do the soldering, that's not the issue. I just don't know how the card reacts to partially "dud" adapter and I'd hate to do unnecessary work.

No need to bother with SoftMPU if all you're gonna do is play GM games through the GUS. GM games are happy with UART MPU-401 interfaces. IMHO I'd rather use the GUS for GM than the LAPC-I, simply because you can then run everything through a mixer and never have to worry about muting anything.

Yes, you can ignore everything else, you only need TXD , +5V and GND pins. The LAPC-I couldn't care less, atm you are using it with nothing connected and nothing strange happens 🤣
The amount of work needed is very little and you have lots to gain IMHO.

MCB-1s pop up on eBay a few times a year and one classifieds sites as well.

PeterLI wrote:

MCB-1s pop up on eBay a few times a year and one classifieds sites as well.

...so they do. 🤣

http://www.ebay.co.uk/itm/ROLAND-MCB-1-MIDI-C … X-/171989059071

Ouch. Well okay, it is unused and still in wraps but nevertheless. But I understand your point. As with everything else retro related you should always bide your time and wait until someone sells at an acceptable price exactly what you are after. Usually it just takes a lot of time.

just build the midi-out ports, use it and when a bargain comes for a mcb-1 you take it 😉

keropi wrote:

Here is the MCB-1 schematic , it seems that if you only want the 2x MIDI-OUT ports it's pretty straight forward, only a 74LS05 h […]
Show full quote

Here is the MCB-1 schematic , it seems that if you only want the 2x MIDI-OUT ports it's pretty straight forward, only a 74LS05 hex inverter along with some resistors are needed.

Say, there's one capacitor (C1) in the MIDI OUT circuit diagram (in parallel with 74LS05 legs 14 and 7). How do you interpret that value, 0.1? Is that as in microfarads?

Yes, 0.1 microfarads (uf), same thing as 100 nF (nanofarads). It should usually be a ceramic capacitor.

With the 74LS05 you can leave unused pins floating, but this may not be the case with non-LS types.

Otherwise, if the LAPC-1 works without the MCB-1connected, it will also work with something partially connected.

Just make sure you use the right +5V pins and right GND pins and dont' short circuit them - I bet there is no fuse so nothing limits the current on 5V wires.

Exactly what Jepael wrote, the 0.1uf cap is just a decoupling one to help the 74LS05...

I just thought to let you know that I ordered the materials for MCB-1 "Lite". Most expensive part was the aluminum case (almost 10€). 😀

Actually I still lack one last component: DB15 game port cable itself. I did order both male & female adapters to attach either one to the case so I could use detachable DB15 male/female or male/male cable but those are a bit "expensive" on eBay (around 20€ incl. shipping no matter whether you order form US or Germany). It's not much I know... but if you consider that all other parts altogether cost me less than that, it's the most expensive part of my little project. Maybe I'll just hunt down one defective or otherwise cheap old joystick and rip the cable from it. It's not like I need the cable to actually be detachable as long as it just works... after all the real MCB-1 has non-detachable one, too.