Amazing for its time, and still fun today
I was given MCS as a gift back when I was a kid. We owned a PCjr at the time. I'm a natural-born piano player with a great ear for music. This program has become a permanent part of my musical past, present and (as long as DOSBox is around) future.
For its time, this app was amazing. It did some really neat tricks with the SN76496, even creating percussive-type sounds (they sound more like water droplet effects than anything). As a notation program, it's excellent for its time. The visual representations of the musical elements are fairly accurate (given the 320x200 resolution) and the scrolling effect is really neat as your song plays back!
It has its own FAT12 interpreter and disk access routines - running independent of DOS because it booted directly off a floppy. A neat trick you could do was to save songs on your own floppy with the .MCD extension (rather than the default MCS) and then put the program in demo mode - it'd cycle through all the songs on your disk with MCD extension and loop. Provided interesting "Background music" if that makes your style.
There are definite limitations in the program but I don't hold any of them against it given its age. First of all, the tempo setting is very discrete and doesn't offer much flexibility, and the majority of the slider puts you in tempos way below 120BPM so you only have maybe 5 or 6 useful tempo choices. It can make some songs sound either too fast or too slow.
There were some other interesting limitations that you could work around with little quirks. For example, the actual output of notes is shifted up one semitone from what you lay down on the staff. So if you put down a C, the actual note played is a C#. I don't know exactly why this is, but if you have perfect pitch (like me) it will bug you a bit.
The range of notes is limited but I think this is more related to the SN76496 than the program. SN76496 chips couldn't easily go below certain frequencies, so the program bottoms out at a low B flat. No, scratch that. An interesting quirk you could do was put a flat on the low B at the beginning of the song (to make the whole song have B flats) and then put an additional flat in a measure, and you'd get the low A. Odd quirk but I've used it in a few of my songs. Only problem is then you'l have to "natural" all the other B notes in the bass staff if you aren't playing in a key that uses B flat.
The staff can be printed out but as was mentioned by Trixter it prints down the left side of the page vertically. The reason I can think of for this is simplicity. It more or less sends the same bitmap it draws on screen to the printer. Yeah they could probably have gotten more elaborate and made it print proper page sheet music, but still, for its time, the ability to do notation on the home computer and print it out at all is still pretty cool.
The Bottom Line
I was hooked ever since I first played with MCS and it's never subsided. I actually kept the PCjr around for quite some time just to run MCS. The PCjr sadly failed miserably and repairing it was out of my budget. I played with MCS in the MESS emulator for a while but it was a pain to use.
Then I discovered DOSBox. I had discovered heaven (haha). It's pretty amusing (And sweet!) to see MCS running in full-screen glory on my little Eee netbook complete with PCjr sound!
I still to this day compose tunes in MCS, and you can even hear some of my recent creations on Youtube at my channel http://www.youtube.com/fuzzyflint (thanks to DOSBox's video capture utility)
For anyone who's interested in playing with old software, who has some musical knowledge, and just wants to have fun, MCS is still a fun program. I have a complete MIDI setup and studio equipment but there's nothing that can compare to MCS in its three-voice polyphonic glory.