The Konami ROM specialities.

Although most MSX progs don't contain obsolete programcode, there are a lot of Konami products wich contain some special extra data .

Language problems.

Being an international compagny with world-wide sales but having it root in Japan, Konami needed to produce two versions of their programs, one for the Japanese market and an English version for the rest of the world. Instead going to the problems of producing two versions of a rom, Konami sometimes chose a rather different aproche. To solve this bilinguistic problem they cramed al the data in one rom. This was possible because the MSX standard prescribes that byte ? of the BIOS-rom contains a land-code. Using this identifier the game showed the English or Japanese version.
Most people have never seen the alternated version, or they would have a Japanese and a non japanese system at home. Now with the aid of emulators everybody can test this 'feature'. Start the emulator as an MSX2 with a rom and start again as an MSX2+. Behold the difference. Here are some examples.
Japanese version English version
There isn't even a translation for this screen of the intro-demo. Ofcourse all the text from the rest of the demo is translated in English. 
I haven't finished the game but I wouldn't be surprised as there were other parts missing in the translation.

To enhance game graphics

Some MSX1 cartridges contained code to make the MSX 1graphics more flashy on an MSX 2 or higher.Just look at the difference between these two examples from Nemesis 3.
MSX 1 version MSX 2 version
To show the color-cycling I had to use some different screenschots. So I made this little, messy animated gif.
  I'm sorry but I couldn't just trow in an animated gif for the MSX2 and leave the MSX1 unanimated. So it seemed like a good idea to show that the MSX could handle large boss-enemies.

Eastern eggs

Hidden features in the konami cartridge make for some good fun.

I'm not only talking about special passwords as in the Galious cartridge. But something very amusing can happen when you insert two cartridges in your MSX-slots.

Some lovely combinations are:
Game in slot 1 Game in slot 2 Effect
RC 737 
Yie Ar Kung-fu 2
RC 725
Yie Ar Kung-fu
If you're nearly dead, your father will appear after a while and drop you a cup of tea.
RC 742
RC 740
Your ship is a twinbee and energy pods are bells. Note that most of the ROM files of Twinbee around are not 
       very good, and too errored to be detected.
RC 749
The Maze of Galious 
RC 746
You start with full vitality and 100 Arrows, Coins and Keys.
RC 751
Nemesis 2 
RC 743
Penguin Adventure
Your ship is a Penguin, and energy capsules are fishes. 
RC 753
RC 749
The Maze of Galious 
100 Coins at the start. 
RC 753
RC 751
Nemesis 2 
<F5> to continue after game over. 
RC 753
RC 752
F1 Spirit
You always have special power (Cles can walk over gaps and Wit can jump mid air once per jump).
This is just a short list, just some of my favorites that I like to use.
On the gallery pages you can have a look at the Konami gallery. You can find some pictures there so that you can see how good the conversions where.
For more info concerning Konami on MSX there is a perfect resource :
The Konami pages of Sean Young
Have a look at it, its great !!!