Difference between revisions of "83Plus:Ports:20"
m (→Read Values) |
(More info on modes) |
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== Comments == | == Comments == | ||
This port is not available on the normal TI-83+. On the normal TI-83+ this port is a shadow of [[83Plus:Ports:00|Port 00h]]. | This port is not available on the normal TI-83+. On the normal TI-83+ this port is a shadow of [[83Plus:Ports:00|Port 00h]]. | ||
| + | |||
| + | This port can contain values of 2 and 3, but the difference in speed is negligible. Using the crystal timers I came to these aproximate vaules. | ||
| + | {| width="30%" border="1" cellspacing="1" bgcolor="white" | ||
| + | | width="40%" | Port Contents | ||
| + | | width="60%" | CPU Clock Speed | ||
| + | |- | ||
| + | | width="40%" | 00 | ||
| + | | width="60%" | ~6.089 mhz | ||
| + | |- | ||
| + | | width="40%" | 01 | ||
| + | | width="60%" | ~14.965 mhz | ||
| + | |- | ||
| + | | width="40%" | 02 | ||
| + | | width="60%" | ~14.980 mhz | ||
| + | |- | ||
| + | | width="40%" | 03 | ||
| + | | width="60%" | ~14.990 mhz | ||
| + | |} | ||
| + | I suggests still using 1 as the speed setting vaule since the total effect ofther vaules are not known. These modes are distiguished by LCD delaying hardware, ports 29-2C. | ||
| + | |||
== Example == | == Example == | ||
| Line 34: | Line 54: | ||
out (20h), a</nowiki> | out (20h), a</nowiki> | ||
| − | 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, | + | 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, especially since both lines are high normally... |
== Credits and Contributions == | == Credits and Contributions == | ||
* '''Michael Vincent:''' Documentation and his faster approach as found [http://michaelv.org/programs/calcs/ports/port20.html here]. | * '''Michael Vincent:''' Documentation and his faster approach as found [http://michaelv.org/programs/calcs/ports/port20.html here]. | ||
Revision as of 12:26, 21 August 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.
This port can contain values of 2 and 3, but the difference in speed is negligible. Using the crystal timers I came to these aproximate vaules.
| Port Contents | CPU Clock Speed |
| 00 | ~6.089 mhz |
| 01 | ~14.965 mhz |
| 02 | ~14.980 mhz |
| 03 | ~14.990 mhz |
I suggests still using 1 as the speed setting vaule since the total effect ofther vaules are not known. These modes are distiguished by LCD delaying hardware, ports 29-2C.
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, especially since both lines are high normally...
Credits and Contributions
- Michael Vincent: Documentation and his faster approach as found here.
