A hidden message begins at address 5000 in the ROM:
HYDLIDE for MSX
by KATO EIJI
ANGOU-CODE O KAIDOKU DEKITAKATAWA, T&E SOFT KATO MADE GOIPPOU KUDASAI. TADASHISUBETE NO BIT NO IMI O KAIDOKU SHITEKUDASAI.
(Translation: Those who were able to decipher the code, please notify Kato of T&E Soft. However, please decipher the meaning of all the bits.)
MY BIRTHDAY IS
(PLEASE GIVE ME A PRESENT)
(note: S40 is short for Showa 40 which stands for the year 1965)
MY CAR IS
(SKYLINE NO TURBO-SOUND WA SHIBIRERU HODO SAIKO-!!)
(translation: The Skyline's turbo sound is so awesome it makes me go numb!!)
MY BIKE IS '
(YAPPARI BIKE WA HAYAI !!)
(translation: Bikes sure are fast!!)