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Jeroen Tel
Developer: Maniacs of Noise
Header: Absent
Content: Programmatic
Instruments: Internal
Target Output
Output - Digital Audio.png Output - MIDI - No.png Output - FM Synthesis - No.png Output - PSG - No.png
Released: 1989
First Game: Stormlord (AMI)
  • jt.*
  • mon.*

JT is a file extension given by rippers retrospectively to music in Maniacs of Noise's first Amiga driver. Some JT files contain multiple songs.

The only confirmed users are Kim T. Christensen and Charles Deenen. Another likely user (and the likeliest developer) is Johannes Bjerregaard († 2022), although all known sources are obscure.

Jeroen Tel is not known to have used this driver, and it is unknown who named it after him and why.

During Unreal (AMI), this driver was superseded by MON (Frederic Hahn).




Released Title Sample
1989-??-?? Stormlord (AMI)
1989-1?-?? Onslaught (AMI)
1990-0?-?? Unreal (AMI)
1990-0?-?? Tusker (AMI)
1991-0?-?? Insects in Space (AMI)

How to Obtain

To rip JT files, you have to figure out where they start and end on disk or in RAM. Thankfully, all known games are ripped into JT already.


The driver works identically among all games. Apart from obviously targeting a different audio chip, it resembles two of Bjerregaard's Commodore 64 drivers, and the demoscene quoted Bjerregaard in August 1989 and 2002 as writing:

I also wrote the player for the Amiga myself.
Amiga - programmed a bit for fun, played games, wrote music (not much)

However, over multiple decades, Deenen mentioned having programmed an Amiga driver. In late 1988, he even told Bjerregaard that he was making "the Atari and Amiga routine Editable for you (without PC)".

After finishing Nightdawn (C64) even later in 1988, Bjerregaard wrote himself a new C64 driver, used in Stormlord (C64) (except on Jeroen Tel's Title Music, which uses Deenen's C64 driver). Everyone arranged by typing hexadecimal numbers directly, whose meanings altogether compare as follows:

Track byte JT Bjerregaard's Stormlord (C64) Deenen's Stormlord (C64) driver
00-3F Play pattern 00-7F Same as JT Play pattern 00-3F
40-5F Repeat next pattern
60-7F Instrument bank
80-BF Transpose down Same as JT Transpose up
C0-FD Transpose up Same as JT
FE Stop entire song Same as JT Same as JT
FF Restart entire song Same as JT Restart track only
Pattern byte JT Bjerregaard's Nightdawn (C64) Deenen's Stormlord (C64) driver
00-1F note Play new note with duration
If note is 80-FF, disable vibrato delay
Same as JT Set duration using 80-BF (chainable)
Play note using 00-5F
Can't disable vibrato delay
20-3F note Tie from previous note (new note ignored) Tie to next note (can change) Tie next using FB
40-7F rate newnote oldnote Same as 00-3F with portamento Same as JT Same using FD rate old new
80-BF instrumentnumber note Same as 00-3F with instrument change Same as JT Same using C0-DF
C0-DF Play rest Same as JT Same using E0-FA,FC,FE
E0-FE Change arpeggio E0-FE instrument rate new old Arpeggio using 60-7F
FF End of pattern Same as JT Same as JT