Re: TI-H: ti-turbo
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Yes. The Z80 chip runs at 6MHz I believe, and the C9 in the meantime is
limiting it down to 2MHz or something. By accellerating your calc, you're
really just pushing it up to a max of 6MHz and no more, or the chip
wouldn't be able to handle it.
"Honors Master PhD of Idea Engineering"
-= Zenon@bbs.nexes.com =-
----------
: From: ti-hardware@lists.ticalc.org
: To: Zenon
: Subject: Re: TI-H: ti-turbo
: Date: October 22, 1996 7:35 PM
:
:
: On Tue, 22 Oct 1996 18:35:35 EDT, you wrote:
: >
: >On Tue, 22 Oct 1996 07:34:05 EDT wesleymcgrew@juno.com (Robert W McGrew)
: >writes:
: >
: >>I can't see why not, if they all have the z80 processor, then TI put
: >>something in to slow 'em all down.
: >
: >This leads to the obvious question: Why did TI slow them down so much?
: >
: >This is the way I see it (please, bear with me... =)
: >
: >The Z80 is a chip that can run at almost any speed, assuming it doesn't
: >get too hot or some other theoretical limit is reached. (Same as with
: >the 80x86/Pentium Intel Chips). Now, from my experiences working with
: >them whilst open, none of the chips ever got more than warm while doing
: >intense calculations (A.k.a. Game Playing). Therefore, since the 85
runs
: >at 6 Mhz (and to my knowledge, minimal thermal trouble...) why not have
: >it automatically sped up to say, 18 Mhz? Surely TI would have noticed
: >that normal graphing operations (Some o which take 10+ mins. including
: >ZFit) would be sped up immensively...
: >
: >Ok, I'm done. If I'm missing something (or if anyone actually
: >understands what I'm trying to say...) let me know.
: >
: > - J. Bishop
: >
:
:
: That's the thing, though, theoretical limits ARE being reached here.
: As the transistors in a chip get smaller (i.e. the sub-micron
: processes that intel is now boasting), three things happen. You can
: fit more of them in the same space, they heat up less, and (most
: importantly) they switch and transmitt signals faster. Now, with the
: Z80, I doubt they're using "cutting edge" manufacturing techniques, so
: each transistor can only switch so fast. Therefore, there's a
: definite ceiling to the maximum speed you can clock it to. If it's
: too fast, certain paths and transistors won't be able to keep up, and
: you'll have a big mess. Heat was never really a problem on the older
: chips, because the darn things were so big that you couldn't fit
: enough of them on there to have generate a lot of heat. However,
: newer processors can have 15+ million transistors on a square
: centemeter, and now heat is a BIG problem!
:
: I really don't see why TI decided to go with an RC clock circuit. A
: crystal would have allowed for timer-dependant applications (like on
: the HP-48's). The only advantages to an RC clock is that it's
: cheaper, and it consumes slightly less power when the batteries are
: getting low. Frankly, I just think TI's too cheap!
:
: Really, though, who said that the TI-85's clock is dependant on the
: battery life? Are you guys sure? There could EASILY be some sort of
: TTL crystal clock circuit built into one of the prefab chips, one
: that's dependant on an RC circuit for calibration only. This would
: make the clock relatively constant at any battery level. If it's a
: non-fundamental mode crystal, this could explain why changing C9 has
: such a dramatic effect on the clock speed.
:
: -Mel
:
: --
: The TI Memory Expansion Homepage
: http://pilot.msu.edu/user/tsaimelv/expander.htm
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