NovaLoad
==============
info by Tomaz Kac ,
Markus Brenner
Encoding:
---------
Bit 0: 511 T-States
Bit 1: 1222 T-States
Data Endianess: LEAST Significant bit First
Pilot Tone is constructed of MANY $00 Bytes (normally 255-257). Pilot end's
when Bit 1 is read. After this bit the actual Data starts.
Still to find out: 100% Correct Timings (Now gathered from TAP files) !
~~~~~~~~~~~~~~~~~~
Structure:
----------
First byte of a block is always $AA which is considered as FLAG byte.
The Second byte read can either be $55 in which case this block is considered
as 'Special' block, if it is anything else than $55 than this is the following
data that is present (including this byte):
1 byte Length of filename (this can be $00 - then no filename follows !)
n bytes Filename
2 bytes Load Address - $100 (you have to add $100 to get actual add.)
2 bytes End Address
2 bytes Length of the block + $100 (here you must substract $100 to get len.)
After this a series of sub-blocks start with the length of DATA being 256 if
there is some more data avialble otherwise the length is whatever is left...
1 byte Checksum so far
n bytes Data (either 256 or less bytes)
This is then repeated until whole data is read in from the 256 long blocks.
After all sub-blocks there is FINAL Checksum ...
The checksum starts with the first byte read (Length of filename) and is
normal addition of all bytes (you have to do checksum = (checksum + byte) & 0xFF
to get correct result). After you check the checksum you must also add it !
If the Length of filename (the byte after the FLAG) is $55 then the block
structure is different:
1 byte Load Address HIGH Byte only
256 bytes Data
1 byte Checksum
This is first repeated UNTIL Load address is $F0 , after which is again repeated
UNTIL Load address is $00 !
The Checksum is calculated the same way as before (starts with the 1st byte AFTER $55).
All blocks also have some TRAILING Tone present after the end of the block.
Still to find out: - Nothing
(
geocities.com/siliconvalley/platform/8224) (
geocities.com/siliconvalley/platform) (
geocities.com/siliconvalley)