Difference between revisions of "83Plus:Ports:24"

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(Created page with '24 - Flash Execution Override 24 - Flash Execution Override [[Category:83Plus:Ports:By_Name|Fl…')
 
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[[Category:83Plus:Ports:By_Address:Protected|24 - Flash Execution Override]] [[Category:83Plus:Ports:By_Address|24 - Flash Execution Override]] [[Category:83Plus:Ports:By_Name|Flash Execution Override]]
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[[Category:83Plus:Ports:By_Address:Protected|24 - Flash Execution Limits High Bit]] [[Category:83Plus:Ports:By_Address|24 - Flash Execution Limits High Bit]] [[Category:83Plus:Ports:By_Name|Flash Execution Limit High Bit]]
 
{{SE-Only Port|04}}
 
{{SE-Only Port|04}}
 
{{Protected Port}}
 
{{Protected Port}}
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'''Port Number:''' 24h
 
'''Port Number:''' 24h
  
'''Function:''' Flash Execution Override
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'''Function:''' Flash Execution Limits High Bit
  
This port overrides [[83Plus:Ports:23|port 23]] and is overridden by port [[83Plus:Ports:22|port 22]].
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Bit 0 of this port forms the high bit of page number for port 22. Bit 1 of this port forms the high bit of the page number for port 23. Therefore, this port supports 8 MB flash chips.
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Since no 8 MB flash chip exists, this port in effect overrides both [[83Plus:Ports:22|port 22]] and [[83Plus:Ports:23|port 23]].
  
 
=== Write Values ===
 
=== Write Values ===
* Bit 0: Set to allow execution on any flash page
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* Bit 0: High bit (bit 8) of port 22
* Bit 1: Set to disable execution on every page except privileged pages, bit 0 and [[83Plus:Ports:22|port 22]] override this function.
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* Bit 1: High bit (bit 8) of port 23
* Bits 2-7: Toggleable, but no effect is apparent
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* Bits 2-7: Toggleable, but no effect is apparent. These bits are currently unused.
  
 
=== Read Values ===
 
=== Read Values ===
* Bit 0: Set if execution is allowed on any flash page
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* Bit 0-7: Reads whatever was last written
* Bit 1: Set if execution is disabled on every page except privileged pages, and pages allowed by bit 0 and [[83Plus:Ports:22|port 22]].
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* Bit 2-7: Reads whatever was last written
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== Comments ==
 
== Comments ==
This port is very strange and not well understood. Bits 2-7 can be toggled so they probably have a use.
 
 
 
This port does not exist on the standard 83 Plus.  See ports [[83Plus:Ports:05|5]] and [[83Plus:Ports:16|16]] instead.   
 
This port does not exist on the standard 83 Plus.  See ports [[83Plus:Ports:05|5]] and [[83Plus:Ports:16|16]] instead.   
  

Latest revision as of 14:52, 20 January 2021

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 04.
This port is protected, which means user programs cannot ordinarily write to it directly.

Synopsis

Port Number: 24h

Function: Flash Execution Limits High Bit

Bit 0 of this port forms the high bit of page number for port 22. Bit 1 of this port forms the high bit of the page number for port 23. Therefore, this port supports 8 MB flash chips.

Since no 8 MB flash chip exists, this port in effect overrides both port 22 and port 23.

Write Values

  • Bit 0: High bit (bit 8) of port 22
  • Bit 1: High bit (bit 8) of port 23
  • Bits 2-7: Toggleable, but no effect is apparent. These bits are currently unused.

Read Values

  • Bit 0-7: Reads whatever was last written

Comments

This port does not exist on the standard 83 Plus. See ports 5 and 16 instead.

See Also