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 *******     Scream Tracker - Technical information     ********
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Program protection:
	The program's protection (the one displaying the
	username in the topline) CAN be cracked, thus enabling
	someone to enter any name on the line. Although the
	topline info is NOT the only name information in the file!
	In fact the name is encoded into over 10 places! Not all
	of them are used in any way, so finding them is practically
	impossible. So even if you manage to remove your name from the
	topline, you can be sure that hidden owners inscription
	is still there (at least a few of them)!

Sample storage on disk:	
	The samples used are stored to disk in 8 bit unsigned format.
	(Amiga uses 8 bit signed format) To convert:
	newbyte=(oldbyte+128) and 255. 
	
VOXKIT samples:
	If you have a soundblaster and have digitized voxkit samples
	you can use them as instruments. Save samples in unpacked format
	and remove the first 32 bytes (which form the header) from the
	VOXKIT files.

Covox specification:
	The Covox in setups means a device converting the printer ports
	8 data lines to analog information (DA converter).

Informing about other output methods:
	If you have knowledge of other PC cards/methods of outputting
	8 bit digital sound, contact the author, and include a description
	of the ouput method (Initialization and how to output a byte)
	and the method will be added to new versions. REMARK that the
	method must be a sequential byte at the time, and NOT for example
	DMA, for sounds must be mixed in real time. See README for how
	to contact the author.

File extension used with Scream Tracker:
	.HLP - Help file
	.STS - Scream Tracker song
	.STM - Scream Tracker module
	.ILB - Instrument library
	.MOD - Amiga module

Scream Tracker program files:
	ST.EXE	 - main program
	ST.HLP	 - help file
	ST.SET	 - saved setup
	ST.ILB	 - main library (library names etc.)
	STxx.ILB - libraries 00-99
	
Amiga conversion file extensions:
	Amiga has 20 byte filenames, and PC only 8 byte ones. Due to this
	fact amiga instrument names must be truncated to 8 chars. To avoid
	confilict with for example BASSDRUM1 and BASSDRUM2 the converter
	calculates an CRC of the entire amiga filename (chars added together)
        and adds a CRC mod 512 to the files extension.
        The examples would become: BASSDRUM.657 and BASSDRUM.658
	
Conversion differencies with amiga:
	Volume Vibrato and Volume Portamento (NT 2.0) are converted
	to funktions K and L, but have no effect in current version of
	ST. The arpeggio command is now implemented.
	
Benchmarks:
	The new ST enables using the Timer interrupt, so benchmarking
	is now easier. With my machine (20Mhz 386SX) and ST playing
	at 12Mhz, my benchmarks showed that ST used 60% of raw processing
	power.
	
Playing frequencies:
	The frequency listed is the frequency at which the samples	
	are mixed. The leftmost column describes the name for the 
	speed (in setup):
	5Mhz AT	  - 5000Hz
	6Mhz AT	  - 6500Hz
	7Mhz AT	  - 8000Hz
	8Mhz AT	  - 9943Hz
	10Mhz AT  - 11932Hz
	11Mhz AT  - 13000Hz
	12Mhz AT  - 15909Hz
	16Mhz 386 - 17045Hz
	20Mhz 386 - 19886Hz
	23Mhz 386 - 23863Hz

Song/Module file structure:
	Offset: Info:
	0       Song/File name, max 20 chars, ASCIIZ, except if 20 chars long
	20      Tracker name, max 8 chars, NO NUL
	28      0x1A
	29      File type: 1=song, 2=module
	30      Version major (eg. 2)
	31      Version minor (eg. 2)
	32      byte; tempo
	33      byte; num of patterns saved
	34	byte; global volume
	36      reserved, 13 bytes
 
	48      Instruments (31 kpl) (see below) Instrument structure:
		Offset  Info
		0       Inst. Filename, 12 bytes max, ASCIIZ
		12      0x00
		13      byte; instrument disk
		14      word; reserved (used as internal segment while playing)
		16      word; length in bytes
		18      word; loop start
		20      word; loop end
		22      byte; volume
		23      byte; reserved
		24      word; speed for mid-C (in Hz)
		26      reserved, 4 bytes
		30      word; internal segment address/(in modules:)length in paragraphs
 
	XXXX    Music pattern orders (64 bytes/orders)
	 
	XXXX    Patterns (number in header, each pattern 1KB)
		Patterns consist of 64 rows, each 4 channels. Each channel
		is 4 bytes in length, and the channels are stored from left
		to right, row by row.
		Special [BYTE0] contents:
			 251=last 3 bytes NOT in file, all bytes 0
			 252=last 3 bytes NOT in file, note: -0-
			 253=last 3 bytes NOT in file, note: ...
			 254=(in memory), -0- 
			 255=(in memory), ...
		otherwise:
			note=[BYTE0] and 15 (C=0,C#=1,D=2...)
			octave=[BYTE0] / 16
			instrument=[BYTE1]/8
			volume=([BYTE1] and 7)+[BYTE2]/2
			command=[BYTE2] and 15
			command info=[BYTE3]
	
	[XXXX]	In modules: Samples, padded to 16 byte limits. Sample lengths in
		paragraphs (and as saved) are storen in instruments internal
		segment address.