Correction: it used ZP locations five and six.... but yes, surely both other programmers came up with identical code months later.

Meow.

The Fantasy 1581 disk doctor was released January 28, 1990.

Intro for that release follows the standard format I used:

Start with JSR $E544, set $DC0D and $D01A with #, INC $D019 instead of writing to $D019. Chain the IRQ's together. It used ZP and for scroll text pointer which is not typical of most intros.

The turn off IRQ writes $F0 to $F01A, to DC0D. Calls $FF5B, writes 0 to $d020/d021 immediately after, calls $AB1E for credits, writes # bytes to SID chip to silence it. Instead of JMP to linked program it writes to 00 just in case 00 isn't zero and then calls RUN via A659/A7AE.

Then we have the Brenda import group and the Insane intros both claiming they wrote it. In the end, it's proven who created the intro... but of course, people will believe what they want to believe.

Surely two other groups just coincidentally copied all of the coincidental code from a January 1990 intro of mine :-)

"All Insane rels are from 1990 so this predates BIG and WDR usage, this is probably the original."

csdb.dk/release/?id=198137

Compare the exit routine which turns off the IRQ, calls $AB1E for credit print out and turns off the SID. It is byte-for-byte identical to the exit routine from my 1581 Disk Doctor intro made for Fantasy.

I did indeed make this intro.

probably copied from Insane (US) 01