This is original uncompiled module of Sound Tracker v1.1 – ZX Spectrum AY music editor by Jarek Burczynski (Bzyk) of Pentagram.
The file is just its memory dump from address 25000 (not compressed). It can contain some patterns and all internal structures, samples and ornaments (even unused and not affecting to sounding, for example). Therefore, big number of uncompiled modules has big size.
Original files can be identified on TR-DOS disks by extension 'S' with loading address 25000 and special file size values (see further).
Files with extension ST1 is a just renamed copy of original modules and can be found in various music collections. Also, famous AY-file format can be a container for ST1 (see ST11 data type in AY-files description).
Ay_Emul can search and detect ST1 modules if source file name extension is not ST1 or if "Search for tunes in files" tool is used.
Structure of ST1 was well documented in 1993 by Ramsoft in SoundTracker Technical Reference.
Further you can read part of that document (file ST11FMT.TXT) dedicated to uncompiled song structure.
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UNCOMPILED SONGS STRUCTURE Start address= 25000 (61A8h) Lenght= 3009 (0BC1h)+576 (0240h)x[number of patterns] Start = uncompiled samples Start + 1950 (079Eh) = positions map Start + 2462 (099Eh) = song's lenght in patterns Start + 2463 (099Fh) = uncompiled ornaments Start + 3007 (0BBFh) = delay value Start + 3008 (0BC0h) = patterns lenght Start + 3009 (0BC1h) = patterns data UNCOMPILED SAMPLES STRUCTURE Length= 130 (82h) bytes per sample Bytes 00-31 (00h-1Fh) = envelope values (volumes) Bytes 32-63 (20h-3Fh) = noise values Bytes 64-127 (40h-7Fh) = addition for effects Byte 128 (80h) = repeat value Byte 129 (81h) = repeat lenght value Note: bit 4 of additions is for sign. UNCOMPILED POSITIONS MAP STRUCTURE Lenght= 2 bytes per positions Byte 1 = pattern number in position Byte 2 = height of pattern in this position UNCOMPILED ORNAMENT STRUCTURE Lenght= 32 (20h) bytes per ornament Positive values = normal Negative values = obtained with one's complement UNCOMPILED PATTERN STRUCTURE Lenght= 576 (0240h) bytes per pattern Lenght of location data= 9 bytes (3 bytes per channel) Channel data sequence= A,B,C. Byte n.1: bits 0-2 = octave number bit 3 = flat note flag (0=no;1=yes) bits 4-6 = note name (0=A;7=G) bit 7 = rest flag Byte n.2: bits 0-3 = effect selected number bits 4-7 = sample number Byte n.3: bits 0-3 = low part of effect or ornament number bits 4-7 = high part of effect
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