Commodore 64: Novaload + Novaload Special loader
Probably the most common of all turbotape loaders, it can be found on...
- 1942
- Airborne Ranger
- Airwolf
- Airwolf 2
- Alice in Videoland
- America's Cup Challenge
- Ancipital
- Ballblazer
- Bombjack
- Boulderdash
- Bruce Lee
- Commando
- Batalyx
- Batty
- Beach Head 2
- Beyond The Ice Palace
- Blue Max
- Blue Thunder
- Bombjack
- Bombjack 2
- Breakthru
- Bruce Lee
- Cluedo
- Commando
- Critical Mass
- Dambusters
- Deactivators
- Dropzone
- Fairlight
- Flyer Fox
- Fort Apocalypse
- Ghosts 'n' Goblins
- Gunship
- Hacker
- Impossible Mission
- Mercenary
- Paperboy
- etc...
Note : Most Novaload tapes contain both 'Novaload' AND 'Novaload Special' files.
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Threshold : $1F4 (500) clock cycles (TAP byte = $3E).
Bit 0 : $24
Bit 1 : $56
Endianess : LSbF
Pilot : Bit 0 (*2000+)
Sync : Bit 1
Then...
1 byte : $AA
1 byte : NOT $55 (see Novaload "special" format below)
1 byte : Length of Filename (if 0 then no filename follows)
n bytes : Filename
2 bytes : Start address - 256 (LSBF)
2 bytes : End address (LSBF)
2 bytes : TOTAL data size + 256 (LSBF)
The data file is split into sub-blocks, the largest volume of data in a sub-block is 256 bytes and each has a checkbyte of the data "so far".
the first one follows immediately after main header (above) and each has the following
structure ...
1 byte : Checksum so far
n bytes : Data (256 bytes or less)
Only the last sub-block will possibly contain fewer than 256 bytes, but this of course depends on the TOTAL data size, you can get the TOTAL data size from the main header, so just keep track.
After all sub-blocks there is a FINAL Checkbyte ...
The checkbyte starts with the first byte read (Length of filename) and is normal addition of all bytes (you have to do checksum = (checksum + byte) & $FF to get correct result).
After you check the checksum you must also add it!.
Trailing tone : approximately 2000 Bit 0's.
They occur at very end of each data file. (not after each sub-block).
Important : Trailing tone on Novaload frequently (always?) contains garbage pulses at the beginning that may be have been intentionally written but serve no purpose other than perhaps to confuse crackers, I'd strongly recommend they be overwritten with Bit 0's by anyone writing a cleaning tool. (Final TAP does this already).
NOVALOAD SPECIAL
Threshold = $1F4 (500) clock cycles (TAP byte = $3E).
Bit 0 : $24
Bit 1 : $56
Endianess : LSbF
Pilot : Bit 0 (*2000+)
Sync : Bit 1
After sync bit is...
1 byte : $AA (FLAG)
1 byte : $55
Then the sub-block chain begins, each sub-block is orgainised as follows ...
1 byte : Start address (high byte)
256 bytes : Data
1 byte : Checksum
Notes:
Data is structured as a chain of 256 byte sub-blocks, they are written out consecutively without pauses between them. The first sub-block has pilot tone (2000+ pulses) and the final sub-block has trailing tone (2000+ pulses).
The Checksum is calculated the same way as standard Novaload (starts with the 1st byte AFTER $55).
There is NO final checksum.
Unlike standard Novaload, this format is flexible in where each sub-block loads, meaning that ALL program files may be contained within a single chain.
