83Plus:Ports:2F

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