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


Port Number: 16h

Function: Flash Sector/Page Exclusion

This port controls which sectors or pages of Flash may contain executable code.

Read Values

  • Nothing useful (mirror of port 14, I think.)

Write Values

  • Each bit maps to a page, as determined by port 5. Set a bit to disallow execution on that page.


The above only applies to the 83+ basic. It does nothing on other models.

This port is protected, just as port 14 is; it is the only other protected port in the original hardware. Note that as with most protected ports, Flash must be write-enabled for writing to have any effect.

It is used, as are ports 22 and 23 on the SE, to prevent code in the archive from executing, thus theoretically limiting Flash execution privileges to FlashApps.

An alternate version?

The TI-73 uses this port differently. Instead of controlling individual pages, each bit corresponds to a Flash sector:

  • Bit 0: Set if execution is not allowed in sector SA2 (pages 08-0B.)
  • Bit 1: Set if execution is not allowed in sector SA3 (pages 0C-0F.)
  • Bit 2: Set if execution is not allowed in sector SA4 (pages 10-13.)
  • Bit 3: Set if execution is not allowed in sector SA5 (pages 14-17.)

Credits and Contributions

  • Tijl Coosemans: Documentation here.

See Also