I should be making dinner, but apparently this is more important.
So I did indeed manage to find one of the candidate titles within the vanekp WAV tape archive -- Caveman Adventure
I grabbed "CavemanAdventure(ProgramPower).wav" from this WAV archive, and ran it through Quadbike. By default, Quadbike just produces a CSW output file, but the --inspect-dir debugging option tells it to dump useful intermediate data into various WAV files in a specified directory -- essentially, it allows you to "see what Quadbike is thinking".
Here is the very end of block 0 of the first file on the tape, according to Quadbike.
The top trace here is the 1-bit (2400 Hz) signal power, according to the Goertzel transform employed by Quadbike to identify bits. Below that is a sync stream derived from it, which shows where each pair of half-bits is sampled from the power. The bottom trace is the resulting decoded bitstream, which I have annotated with the bit values. Remember that bytes are sent LSB first, so the bits in each byte are read right to left, resulting in a sequence of DD 7B 7B as the final three bytes in the block.
Similarly, here's block 1:
So we would expect sequences of DD 7B 7B, and 80 31 31, for the final three bytes of the first two blocks on the tape. It certainly looks like there is a single duplicated CRC byte involved here, but what does the hacked Cornfield say about the UEF file from Stairway -- "CavemanAdventure_B.uef"? Does it agree?
Code: Select all
stardot: blk #1: 1 garbage bytes; first matches CRC MSB (7b :: 7bdd)
0x0153 4e dd 7b 7b
stardot: blk #2: 1 garbage bytes; first matches CRC MSB (31 :: 3180)
0x027d 69 80 31 31
You bet it does.