Difference between revisions of "83Plus:Ports:20"
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[[Category:83Plus:Ports:By Address|20 - CPU Speed Port]] [[Category:83Plus:Ports:By Name|CPU Speed Port]] | [[Category:83Plus:Ports:By Address|20 - CPU Speed Port]] [[Category:83Plus:Ports:By Name|CPU Speed Port]] | ||
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== Synopsis == | == Synopsis == | ||
'''Port Number:''' 20h | '''Port Number:''' 20h | ||
'''Function:''' CPU Speed Port | '''Function:''' CPU Speed Port | ||
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This port controls the calculator's CPU speed. The CPU can be set to run at either 6MHz or 15MHz with this port. | This port controls the calculator's CPU speed. The CPU can be set to run at either 6MHz or 15MHz with this port. | ||
Revision as of 12:59, 30 March 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 00. |
Contents
Synopsis
Port Number: 20h
Function: CPU Speed Port
This port controls the calculator's CPU speed. The CPU can be set to run at either 6MHz or 15MHz with this port.
Read Values
- 00h : The CPU is running at 6MHz.
- 01h: THe CPU is running at 15MHz.
Write Values
- 00h : Set the CPU to 6MHz.
- 01h: Set the CPU to 15MHz.
Comments
This port is not available on the normal TI-83+. On the normal TI-83+ this port is a shadow of Port 00h.
Example
in a, (2) and 80h jp z, NoCPUGoverner rlca ;Move the 1 bit in bit 7 to bit 0 (80h -> 01h) out (20h), a NoCPUGoverner:
Michael Vincent documented another method to set the CPU speed (which is probably faster than my example).
in a, (2) rla sbc a, a out (20h), a
The only side effect of this is that on the TI-83+ Basic this will cause both linkport lines to go high - which shouldn't matter too much if you're not using the linkport at that time, especailly since both lines are high normally...
Credits and Contributions
- Michael Vincent: Documentation and his faster approach as found here.
