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Z80 Clock v1.0 for TI83+SE, TI84+ and TI84+SE.
AVELINE Nicolas
email : francis.aveline@electricitestrasbourg.fr

Introduction :

	This program measures the CPU speed by using a timer based on the 32.768kHz oscilator. That is why he can not run on a TI83+. He is useful for overclockers who can know the CPU speed with a precision of 0.001Mhz ! Note that the frequency depend of the temperature and the battery state because the CPU clock is based on a RC oscillators.

How it works :

	When an APPS or an ASM program is executed, the TIOS set the clock to 6MHz. For set the speed to 15Mhz an APPS must have an additional header tags and an ASM program do a B_CALL SetExSpeed (50BFh). Read the "Addendum to the TI-83 Plus Developer Guide" for mor informations. The program set the clock to 15Mhz for measures it. The measure bring 0.5s. Firstly, HL is set to 0 and the first crystal timer is configured to 8 Hz and the counter to 4. The loop increase HL at the speed of the CPU clock divided by 500 until the first crystal timer has expired. If HL = 1, it would say that there are 500 clocks in 500 ms, or 500/0.5= 1000 Hz. When the timer expired, HL is the clock speed in kHz. So it is possible to measure up to 65.535 Mhz !

Contents :

	There are two versions of this prog so you can run directly the program in TIOS or with MIRAGEOS.

For more informations :

-TI-83 Plus Developer Guide
-Addendum to the TI-83 Plus Developer Guide
-http://wikiti.denglend.net/
-http://240gp.ovh.net/


