Difference between revisions of "83Plus:Ports:29"

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m (Renamed to better fit it)
(Synopsis: ... effect is somewhat more general)
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'''Function:''' LCD Delay (6 MHz)
 
'''Function:''' LCD Delay (6 MHz)
  
This port removes the amount of delay needed between accesses to the lcd driver by adding tstates to the following instructions:
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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 [[83Plus:Ports:10|10]] or [[83Plus:Ports:11|11]], as well as the mirror ports 12 and 13.
* out (010h),a
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* in a,(011h)
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* out (011h),a
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=== Usage ===
 
=== Usage ===
  
Bits 0&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.
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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.
 
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Bits 2-7 control the amount of delay added at specified instructions. To calculate the tstates added divide the contents of port 29 by 4 and round off.  
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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 ==
 
== Comments ==

Revision as of 14:48, 8 August 2005

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.