The TPDD2 service manual in all of its glory...
While going through starting to update dl2 with all this new info, I
also tried a new (old) DOS I recently found called PAKDOS by James Yi.
http://tandy.wiki/TPDD_client:PAKDOS
And it tries to use a command 0x47 every time it does a directory listing.
Well that's a new one. Never saw request format 0x47 anywhere before.
I figured out what it is and it's weird.
PAKDOS apparently expects no-response might be possible since it doesn't
care that dl2 ignores it, and the directory listing works with no hint
of any problem on the portable side.
The command is given with no parameters or payload data, and wrapped in
a valid Operation-mode packet, IE, the packet has all components and is
consistent.
format byte is 0x47
there are no params or data, and the len byte is 0x00, so that fits,
and there is a checksum byte 0xB8 after that, which is correct.
So, it's not just random data.
The first guess maybe it's a synonym for drive_status, because:
* 0x07 is drive status
* drive status has a payload length of 0
* for TPDD2, some commands do have an alternate version that is the
normal format code plus 0x40 to make the command operate on bank1
instead of bank0.
all checks out and adds up
But a real TPDD2 does not respond to this command.
... BUT a TPDD1 DOES, and it indeed does the drive status command.
It doesn't just respond with a valid standard 0x12 return format for
"ok" but for instance if the disk is ejected it says so.
Whatever! Easy enough to handle, just completely unexpected that a tpdd1
would respond to a 0x4n request and a tpdd2 does not!
--
bkw
