I know the TI 83 plus has a 6 MHz Z80 CPU. However, the TI 84 plus got a 15MHz Z80 with a 6 MHz compability mode.

However, it really looks like Basic programs runs just as fast on the 83 plus compared to the TI 84 plus. If that's true, the rest of the OS is also most likely to run at 6MHz. If I'm rigth, wouldn't it bee a great advantage to make a program that set the CPU to 15MHz?

My question is if TIOS for the 84-plus utilizes this 15MHz mode or if it runs in 6MHz compability mode?

One final note, it seems like most programs/apps written is written for 6MHz mode. This gives certain limitations when it comes to speed, and I guess some programs could have been made faster by being availble in a 15MHz form.

Actually, the 84+ runs at 15MHz of you compare two programs that just count up, it will run faster then the 83+

Assembly programs switch between 15MHz and 6MHz mode by setting or resetting a bit of one of the ports. As you note, some things run in 6MHz mode, such as the TI-BASIC parser, to avoid incompatibility, although shells can of course set 15 MHz mode before invoking the parser to override this. In the vast majority of the cases that I've seen, it's not worth it to design purely for 15MHz. The slower speed is often more than enough to get a good game speed or program execution speed given good coding and optimization skills, and the programmer then avoids making their program incompatible with the dozens of millions of TI-83+ calculators out there.

I understand... However, I was more thinking about not making programs only for 15MHz mode, but programs that activated "complex mode" if 15MHz mode is availble. A good candidate would have been the recent GameBoy-emulator written for the TI-83 plus calculators some time ago. It would be great to play "Link's awakening" at full speed with minimal frameskipping.

Is there any posibility for you to add an (optional) option to the next version of Doors CS, making it run BASIC programs in 15MHz mode if availble? It would make Design 3D quite faster to use.

The emulator already runs at 15MHz, don't be silly.

Oh, sorry then, I don't really have an 83 Plus to compare with. My bad.

Well it doesn't run on the 83+ actually due to the fact that it doesn't have the RAM required

This is true.


Pardon me for going off-topic, and this might be an incredibly silly/newbish question, but whats an example of the speed differences between 6MHz and 15MHz? For instance, 6MHz = **** cycles/per **? Just curious.

It's raw number of cycles per second, 6*10^6 vs. 15*10^6. However, this does not necessarily always translate to a 2.5x increase in speed, although in this case it does. CPS (cycles per second) can only be used to compare two CPUs in the context of the number of CPI (cycles per instruction) and the relative power of each instruction. On a z80, a single instruction like a ld or pop or cp or dec may take from four to eleven or more cycles, so you get sometimes close to an order of magnitude fewer instructions per second than clocks per second. In addition, whereas each z80 instruction performs some kind of 8-bit or 16-bit ALU, load/store, or I/O instruction, more complex architectures might be able to do more per instruction, such that an x86 processor at 15MHz with a CPI around 4-11 might have more raw computing power than the 15MHz z80 that we're dealing with.

Long story short, the 15MHz calculators are indeed 2.5x faster than the 6MHz calculators.

Good lesson! Thanks Kerm lol
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Just a bit of a note, one that is still a topic of debate, but I have tested myself, is that the 84+ and 84+SE, while being faster than the 83+, is however slower than the 83+SE. Speculation as to why is possibly the clock, or maybe the USB ports, or whatever, but running basic programs between those three calculators, the 83+SE actually comes out on top.

I only know this because I tested Age of Darkness Revenge out on all three calculators, setting them up to all three to draw out the map at the exact same time, the 83+SE beat the other two while they still had several sprites to draw out.

I do know that there is some hardware that adds in wasted clocks for various types of memory reads or writes, and that it's different on different models.

Could one take an 83+SE and modify it to utilize the 15MHz processor? It'd be interesting to see an uber-fast modded calculator

Ummm... "In 2001 the TI-83 Plus Silver Edition was released, which featured approximately nine times the available Flash memory, and over twice the processing speed (15 MHz) of a standard TI-83 Plus, all in a translucent "sparkle" grey case."

Oh... oops.

Wasn't exactly up-to-speed on the 83+SE specs. My bad.

lol

How about the N-Spire 84+?
I've heard that it is actually slower than a normal 84+...

To be honest, I am uncertain. It would make sense because of the larger display it has to compensate for.. I will have to give it a shot later and see.

That, and TI almost never writes optimized code.

I prefer IPC

Sadly... They're too lazy to