Difference between revisions of "83Plus:Ports:2F"

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(Rewrote with more accurate data, someone may want to rephrase a few things.)
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'''Function:''' LCD Wait Delay
 
'''Function:''' LCD Wait Delay
  
After every write to the LCD bit 1 of [[83Plus:Ports:02|port 2]] resets for a certain amount of time. This port controls that amount time.
+
After every write to the LCD bit 1 of [[83Plus:Ports:02|port 2]] resets for a certain amount of time based on the current cpu speed and if the calculator is in hi speed mode. This port controls that amount time.
  
  
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=== Write Values ===
 
=== Write Values ===
* Bits 0-1 control the amount of time when port 20 contains 1. The following values tell the amount of time.
+
* Bits 0-1 control the amount of tstates to wait when port 20 contains 1. The following values tell the number of tstates.
** 00 = ~3.2 microseconds
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** 00 = 048 tstates
** 01 = ~7.4 microseconds
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** 01 = 112 tstates
** 10 = ~11.7 microseconds
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** 10 = 176 tstates
** 11 = ~16.0 microseconds
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** 11 = 240 tstates
  
* Bits 2-4 control the amount of time when port 20 contains 2. The following values tell the amount of time.
+
* Bits 2-4 control the amount of tstates to wait when port 20 contains 2. The following values tell the number of tstates.
** 000 = ~3.2 microseconds
+
** 000 = 048 tstates
** 001 = ~7.4 microseconds
+
** 001 = 112 tstates
** 010 = ~11.7 microseconds
+
** 010 = 176 tstates
** 011 = ~16.0 microseconds
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** 011 = 240 tstates
** 100 = ~20.2 microseconds
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** 100 = 304 tstates
** 101 = ~24.5 microseconds
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** 101 = 368 tstates
** 110 = ~28.8 microseconds
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** 110 = 432 tstates
** 111 = ~33.0 microseconds
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** 111 = 496 tstates
  
* Bits 5-7 control the amount of time when port 20 contains 3. The following values tell the amount of time.
+
* Bits 5-7 control the amount of tstates to wait when port 20 contains 3. The following values tell the number of tstates.
** 000 = ~3.2 microseconds
+
** 000 = 048 tstates
** 001 = ~7.4 microseconds
+
** 001 = 112 tstates
** 010 = ~11.7 microseconds
+
** 010 = 176 tstates
** 011 = ~16.0 microseconds
+
** 011 = 240 tstates
** 100 = ~20.2 microseconds
+
** 100 = 304 tstates
** 101 = ~24.5 microseconds
+
** 101 = 368 tstates
** 110 = ~28.8 microseconds
+
** 110 = 432 tstates
** 111 = ~33.0 microseconds
+
** 111 = 496 tstates
  
 
== Comments ==
 
== Comments ==

Revision as of 05:27, 5 October 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 07.

Synopsis

Port Number: 2Fh

Function: LCD Wait Delay

After every write to the LCD bit 1 of port 2 resets for a certain amount of time based on the current cpu speed and if the calculator is in hi speed mode. This port controls that amount time.


Read Values

  • This port reads the last value written to it.


Write Values

  • Bits 0-1 control the amount of tstates to wait when port 20 contains 1. The following values tell the number of tstates.
    • 00 = 048 tstates
    • 01 = 112 tstates
    • 10 = 176 tstates
    • 11 = 240 tstates
  • Bits 2-4 control the amount of tstates to wait when port 20 contains 2. The following values tell the number of tstates.
    • 000 = 048 tstates
    • 001 = 112 tstates
    • 010 = 176 tstates
    • 011 = 240 tstates
    • 100 = 304 tstates
    • 101 = 368 tstates
    • 110 = 432 tstates
    • 111 = 496 tstates
  • Bits 5-7 control the amount of tstates to wait when port 20 contains 3. The following values tell the number of tstates.
    • 000 = 048 tstates
    • 001 = 112 tstates
    • 010 = 176 tstates
    • 011 = 240 tstates
    • 100 = 304 tstates
    • 101 = 368 tstates
    • 110 = 432 tstates
    • 111 = 496 tstates

Comments

This value really shouldn't be changed. TI-OS depends on this being set high enough to function for the LCD delay.

Also the 83+SE has this port set to 4A as default, the 84+(SE) has this port set to 4B as default.


Credits and Contributions

  • James Montelongo