Commodore 64: Cyberload F1 loader
Threshold : varies between tapes.
Endianess : MSbF
The loader code (LOADER1) is contained (enciphered) in the "spare" 171 bytes of the CBM Header block, it is deciphered by a program in the CBM Data block.
The files it loads are organised within a chain...
Pilot byte : Varies between tapes (commonly $0F) (*128)
Sync byte : Varies between tapes (commonly $F0)
File Chain follows...
Each file in the chain has the following format ...
1 byte : Load Offset.
The offset between the End Address of the previous file and the Start Address of the current one, if there was no previous file then use $FFD5 as initial end address.
(Hint : 1st file always has offset of $2D, giving a Start Address of $0002).
n bytes : Data
Each byte is followed by an extra bit, if the bit is set(1) then another data byte follows, if the extra bit is clear(0) then we reached end-of-file, the byte before it is NOT data and may be disregarded.
1 bit : Following File Flag.
If set(1) then another file follows immediately, else we have reached the end of the chain.
Notes :
Following the chain is always 1 more byte, usually containing $00.
The only files found so far written in this format are Cyberload Loader 2, and other loader/protection related files. (ie. no actual GAME data).
Cyberload tapes examined so far only contained 1 file-chain of this format, immediately following the CBM boot files.
