ti-emu: Oops, small update to V86 (v1.3b) and also, the _REAL_ speed of


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ti-emu: Oops, small update to V86 (v1.3b) and also, the _REAL_ speed of a TI-86




Oops! I made some small mistakes in my code on the last update of Virtual 
86.  V86.TXT claimed that one could upload files in Free Mode, this was not 
the case, but it's fixed now, you _CAN_ upload files in Free Mode.  Also, 
Free Mode was interrupting as if it were to emulate a 1MHz processor, 
(obviously wrong) it's been fixed back to interrupt as if it were to emulate 
a 4MHz processor, now as for the comments I will no doubt recieve as a 
result of this "mistake" in claiming that the TI-86 runs at 4MHz....

I'M NOT WRONNG! AND I'M NOT MAKING IT UP!!!

Now, as for proving my point, I have a test posted on my site, it requires 
an emulator which accurately displays it's megahertz, (or at least has a 
fixed well defined megamhertz) and can break BASIC programs (I know of one 
emulator that can't do so.)  _BUT_ since I _KNOW_ no one is going to visit 
my site to read the test, I'll detail it shortly here:

First, make the short program below:
:0->C
:Lbl L
:C+1->C
:Goto L

You'll need it on both your calculator and your emulator, and make sure the 
code is EXACTLY the same... Otherwise the test becomes moot (you know, when 
testing things in science, only one variable right?)  Now, run both of them, 
then break them.  The program is now compiled and waiting for re-execution.  
At this point execute the program as close to exactly the same time on both 
the calculator and the emulator.  Now, let it run, the longer you wait the 
more the error of different starting times dimishes.  Now, break them 
simultainiously, and look at the values of the variable C on both.  (If the 
emulator is supposed to accurately emulate, then this number should be 
fairly equal, but as with V86, you can sometimes unlock the processor speed, 
and then these numbers will likely be different)  Now, if you know the speed 
the emulator was running at, at the time you were running the BASIC program 
above, you can figure out the speed of a real TI-86 by taking the speed of 
the emulator, multiplying it by the value of C on the calculator, then 
dividing by the value of C on the emulator.  The answer is the speed of the 
TI-86!  (It always came out to approximately 4 for me, even adjusting the 
interrupt interval, and refresh rate)  Now, it's important to choose an 
emulator that accurately emulates the TI-86, you're running the same ROM 
version on both the emulator and calculator (like you should be doing 
anyways), and that the emulator locks it's speed based on the T-States 
(which is the same as a clock cycle, and thus the number of T-States in a 
second is the hertz of the processor), also that it keeps track of the 
T-States accurately.  Now, Virtual86 has all these qualifications if you 
hold up your part of the bargain.  But if you _REALLY_ don't believe me, 
then go ahead and try this on your own emulator (so long as it counts 
T-States, it won't help to count instructions per second) and let me know 
the results.  I'm interested in seeing them.

Thanks again for your time,
Daniel Foesch


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