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1050 Turbo mode in APE
https://atarimax.com/flashcart/forum/viewtopic.php?f=5&t=1465
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Author:  lemiel [ Sat Jan 18, 2014 2:18 pm ]
Post subject:  1050 Turbo mode in APE

Hi.

I know you are some kind of busy, so only asking.

Could you add '1050 Turbo' mode to APE?

German (probably most similar to original documentation?) http://www.strotmann.de/%7Ecas/Infothek ... _turbo.pdf
Sometimes this turbo is also called 'Top Drive' and protocol is used also in TOMS and Tygrys extensions.
(This is mostly copy&paste from: http://atariage.com/forums/topic/191852 ... try2485682 )

It is working this way (translated from atariki):
Block command (Command Frame) for the drives, as well as in the standard, it is sent at a speed of 19.2 kbps.
The fourth byte of the block, carrying a byte value DAUX2 DCB block, is increased by 128 (ORA #$80).
After sending the command computer - without waiting for an answer - system reprograms POKEY at 68.2 kbps (counter value (HS Index) - $06) assuming that that drive also switches to the fast transmission.
Pick any negative answer of course is not possible in such a system - this is why attached below atr image is not booting.
Further exchange of data caused by this one command is in an accelerated rate.
After transmission the command returns to standard speed.
Read schema:
speed 19.2 kbps
computer --> command 4 B + CRC --> drive
switch to 68.2 kbps
computer <-- confirmation 'A' <-- drive
execute
computer <-- confirmation 'C' <-- drive
computer <-- data block + CRC <-- drive
switch to 19.2 kbps
end

Write schema:
speed 19.2 kbps
computer --> command 4 B + CRC --> drive
switch to 68.2 kbps
computer <-- confirmation 'A' <-- drive
computer --> data block + CRC --> drive
computer <-- confirmation 'A' <-- drive
execute
computer <-- confirmation 'C' <-- drive
switch to 19.2 kbps
end

It is emulated in Altirra.

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