D64 - A program to convert C64 programs from datasette to amiga
         file format for use with TheA64Package etc.


   This program is public domain software!
   You can do with it what You want!

   The archive contains the following files:

   d64            ;the programm itself
   d64.c          ;the C-Source
   d64.dok        ;German documentation
   d64.doc        ;this documentation file
   Sample1.8svx   ;digitized sample of a C64 datasette program
   Sample2.8svx   ;the same in valid format for D64
   Bild1.ilbm     ;Illustration 1
   Bild2.ilbm     ;Illustration 2





Program description:
--------------------

This program converts C64 programs from tape (TURBO TAPE 64).
To use them from C64 emulators like "TheA64Package" when you
have no C64 with datasette and floppy, digitize the file you
want to convert with a sound digitizer and a program like
Audiomaster with maximal sample rate (more than 40 kHz).
Then zoom to the start (Audiomaster shows a length of 599 Bytes)
an cut the tape noise at the start so that you can hear the
sync signal clearly. It doesn't matter if you cut 1/3 of the
sync signal, but the sound sample must start directly with the
sync signal; that means that you can see waves that are repeating
seven little and one bigger waves. It is not important if it starts
with a bigger wave or one of the lower waves, but you *must* be
able to differ series of 7 lower and one higher wave.
If you have cutted the start of the sample as described, save the
sample, which can now (hopefully) be the input of D64.


Format of a TURBO TAPE 64 file:
-------------------------------

1. Synchronisation:
   - 5 x (246 x byte value 2)
   - Countdownbytes 9,8,7,6,5,4,3,2,1
2. Header:
   - Secondary address 1
   - Low- and Highbyte of the start address
   - Low- and Highbyte of the end address
   - Fillbyte (0)
   - Filename
   - the rest of the 193 header bytes are spaces
3. Synchonisation:
   - 2 x (246 x byte value 2)
   - Countdownbytes 9,8,7,6,5,4,3,2,1
   - Null-Byte
4. Data
5. Checksum: EXOR of all data bytes (255 times)


If you don't like to cut the start of the sample to get it in
the right format for D64, start sampling at the time you hear
the sound of the first sync signal instead of the tape noise
and your sample is cutted. Check it by zooming and looking at
the first 599 (Audiomaster) bytes.

Now start D64 with the following syntax:

D64 <sample> <c64 file>

If you get the output "Prüfsumme OK!" (checksum OK), then your
sample file was successfully converted.
The message "Prüfsummenfehler" (checksum error) could have two
reasons:
- one or more bytes have been swapped
- one or more bytes are to much or are missing
In the first case, you might have luck and the program works
(imagine a program with a wrong graphic byte - that would not
cause more problems than a slightly wrong graphic output, but a
wrong byte in the code...), but in the second case your whole
program had been shifted by one bit - that's not very good...!
When you get the message "Wellenlängeninkonsistenz" (that means
that the length of one or more waves is not correct) you may be
able to fix it because you get the byte number and can have a
look at the wave at this byte - sometimes one wave is drifting
away so that it is completely over or under the middle line
(zero line) - and you can manually correct the wave.


Here is an example of the use of D64:

d64 Sample2.8svx RAM:clock

gives the following output:

SEARCHING FOR DH2:TMP/SAMPLE2
LOADING
-->Header:
   - Sekundäradresse: 1
   - Startadresse LO: 1
   - Startadresse HI: 8
   - Endadresse   LO: 54
   - Endadresse   HI: 11
   - Dateiname      : THE BIG CLOCK                           
-->Prüfsumme OK!
SAVING
READY.


In the archive you will find two files Sample1.8svx and Sample2.8svx
with the C64 program "Big Clock" as a digitized example file from
datasette. Sample1 contains tape noise and would cause an error.
Sample2 has been cutted and starts with the sync signal. The files
should look like in Picture 2 (file "Bild2.ilbm"). Picture 1 shows
the datasette file format as it has been described below.