New guy with a question

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Summary:

Is there any way to determine computer/calculator speed in Ti 83 and adjust game appropriately?

New guy with a question

DakotaWriter 26 Jun 2013 19:59

Hi all,
I recently started Ti Basic, and after a year of learning Java, am immensely enjoying the relative ease of GUI interfaces in TI. I am working on a sidescrolling game, something like the old Pitfall game, and have the Ti 83 Flash Debugger on my computer, which I would like to use for testing as I develop the program.
Here's the situation: As the game progresses, I want the player to move faster. Thus, I'm putting a time delay into the program based on a for( loop, and as the game progresses, the control decreases by a given percent.
On Ti 84 - not 83 like the emulator I downloaded - I want to use a set of code at the beginning to determine the speed of the calculator. From that, I determine the initial control variable value for the delay loop.
In essence, near the very beginning of the Ti84 program, there is a block of code…

ClrHome
Output(3,1,"Loading...
Output(4,1," Computer Speed 
0->S  //S is used to determine speed later
startTmr->T
Repeat checkTmr(T)>=10
S+1->S
Output(5,8,checkTmr(T
End

In Ti 84, this should
(1) Let user know what is going on
(2) Get a value for S over a time of 10 seconds, thus determining speed of computer
(3) Let user know how much time is left
Correct?

If that's correct, is there a way to do anything similar that can include Ti 83 as well, so I can test it on my (much faster) computer, and so that is portable?
Is there another, easier way to determine speed?
Thanx.

Last edited on 26 Jun 2013 20:00 by DakotaWriter Show more

Re: New guy with a question

Roguebantha 26 Jun 2013 21:23

Several things:
One, the only reason that your calculator could be slowing down (upon rereading, I'm not sure if I understood you correctly) as the program continues is because you have a memory leak, most likely a goto inside a for, while, or repeat loop. The other possibility is that the program calls itself without returning. If either one of those happens, find some way to avoid doing this. Furthermore, it's recommended you use rand to slow down the calculator as its smaller than a for loop, for example:
rand(3
Also, the speed of a TI84 calc is 15 MHz and the speed of an 83 is 6 MHz if you want to get down into the nitty gritty.

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Re: New guy with a question

DakotaWriter 27 Jun 2013 04:20

Thanks for the specifics, but I'm hoping to design the program so that I won't have to worry about them.
My plan, which I guess I should have outlined earlier:

1. determine speed of current device by (a) starting timer (b) making the calculator count up by ones at full speed, saving the number, which on the ti 83 is about 106, to S (c) stopping timer and counter when ten seconds have passed.
2. later, use a given percentage of S as the control (highest value) of a for( loop between moves. As the program counts, the calculator will slow down like I want it to do.

So, the problem is not that the calculator slows down - that is on purpose - but that this only works on Ti 84 as far as I know, since startTmr-> and checkTmr( are only available on the 84. I would like to work with the 83 as well, if possible; or I'd like to find an alternate, more dependable way of calculating how fast the calculator will be going that doesn't rely on timings like this.
Interesting that 84 is that much faster naturally.

Re: New guy with a question

Roguebantha 27 Jun 2013 17:53

You actually shouldn't really need to time the calculator and see how fast it goes…all TI-84's will run at the same speed as other 84's, and all TI-83's willl run at the same speed as other 83's. This means that once you come up with nice constants for each calc, you shouldn't have to calculate them every time.

Yes, startTmr and checkTmr are indeed only available on the TI-84, although I'm sure you could get some sort of timer working if you tried hard enough.

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Re: New guy with a question

Xeda Elnara 27 Jun 2013 11:00

If you are willing to use a short assembly code, this will tell you whether your calculator will run a BASIC program at 6MHz or 15MHz:

AsmPrgm
DB0207E601
EF8C47EFBF4A
C9

Note that this must be an external program (unless you are using other libraries like DoorsCS7, Omnicalc, Celtic 3, or BatLib which will allow you to execute opcodes from a BASIC program).

1 is returned for a 15MHz calculator, 0 is returned for a 6MHz calculator.

In actual application, most calculators will run slightly faster than 15 and 6 MHz, respectively. The low speed setting is usually ~6.2MHz, and the higher speed setting is about 15.8 and sometimes a little over 16MHz.

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Z80 Assembly>English>TI-BASIC>Python>French>C>0

Re: New guy with a question

DakotaWriter 28 Jun 2013 01:37

Roguebantha - Wow. Proves my ignorance. So… your speed is independent of the amount in RAM? For example, if I define a new 100x100 matrix with huge values, it should have 0 effect on the speed of the program? Honest question, sans implications.

Another question: I ran my timer (exact code below) multiple times, with slightly different results. You know, over ten seconds, the calc counts up to 106, 113, 101, etc. Isn't this due to a difference in speed?

LCOMP(1) is speed, and starts equal to 0

10->C
startTmr->T
Repeat checkTmr(T)>=C
|LCOMP(1)+1->|LCOMP(1
End

Xeda - Thanks for the code, but as of yet, I haven't even moved off the home screen; much less into assembly.

Now, why I wanted the timer: I have an emulator for my laptop, the 83 flash degbugger, and it is running at a MHz at least slightly higher than either Ti Calculator. I wanted to be able to test the game on it using the time delay between moves.

The good news: I did develop an option. I made a menu, asking which calculator the user is using, and if it 83, I have them time it manually (counting to ten or an external watch). I know that the values will not correspond exactly, but for my casual purposes, it works.

Thanks for the input, both of you.

Last edited on 28 Jun 2013 01:38 by DakotaWriter Show more

Re: New guy with a question

Weregoose 28 Jun 2013 04:46

Speed is proportional to battery life and the amount stored in RAM, which is provable by doing the test you described. I encountered this when coding an accurate clock on the 83+.

Re: New guy with a question

Roguebantha 28 Jun 2013 17:46

On the other hand, you can expect different calculators to act in the same way, at least for the most part. Yes, programs can slow down especially if the calc has very low memory available, but there's not a really big difference between calcs, so treat it as such.

The cpu speed is always the same though (not technically true but very close).

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Re: New guy with a question

DakotaWriter 29 Jun 2013 00:14

Did the clock work? I mean, was it accurate, independent of battery and RAM?
Also, is the inbuilt clock in the 84 accurate regardless of RAM?

Re: New guy with a question

Roguebantha 29 Jun 2013 12:14

The TI-84 clock is and considering that it's Weregoose, I'd be surprised if it didn't work.

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