83Plus:Ports:29

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This port only exists as a distinct port on the TI-83 Plus Silver Edition, the TI-84 Plus, and the TI-84 Plus Silver Edition. On the standard TI-83 Plus, it acts as a shadow of port 01.

Synopsis

Port Number: 29h

Function: LCD Delay (6 MHz)

This port removes the amount of delay needed between accesses to the LCD driver by adding a delay to any instruction which reads from or writes to ports 10 or 11, as well as the mirror ports 12 and 13.

Usage

Bits 0 and 1 are unknown, but don't seem to directly remove the needed delay. On the 83+SE these are reset, on the 84+(SE) these are set.

Bits 2-7 control the amount of delay added at specified instructions. To calculate the number of clock cycles added, divide the contents of port 29 by 4 and round off.

Comments

This port is not available on the normal TI-83+. On the normal TI-83+ this port is a shadow of Port 01h.

Bits 0&1 seem to tie to port 2E, they affect the cpu speed reduction the port 2e contorls. Though their exact purpose is not known.


Credits and Contributions

  • Michael Vincent: Documentation as found here.
  • James Montelongo: Documentation found at here.