[TI-H] TI-83P SE hardware, looking for thoughts
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[TI-H] TI-83P SE hardware, looking for thoughts
I'm not a hardware guy, I'm much more inclined to the software side of
things. However, as of recently I've been intrigued by some hardware stuff
on my 83 Plus Silver Edition, and was just wondering if anyone on this list
had any thoughts.
First of all, scans of the boards of both the regular 83P and the SE are
available here:
http://tcpa.calc.org/members/dan/83plusin.zip
http://tcpa.calc.org/members/dan/83psein.zip
...There are a few changes, IE. the CPU appears to be integrated into the
custom TI chip on the SE, where-as it used a real Zilog Z80 on the 83P, etc.
One thing that interests me is the addition of a 32.768 khz xtal. From what
I've read, the most common use of such an xtal is for an RTC, and I wanted
to see what opinions were on whether this is possible/likely, or what
alternative explanations for the xtal could be.
To preemptively answer a few questions:
-What makes you think the xtal isn't for CPU control?
A) Why 32.768 khz?
B) Playing around with the hardware ports, I found some programmable timers
(http://tcpa.calc.org/members/dan/SETimers.txt). You can set the timers to
use factors of either the xtal speed or the current CPU speed, or you can
mix the two frequencies, which would seem to indicate that they're not one
and the same.
-How could TI add an RTC and keep it compatible?
...Well, for the moment TI looks like they want to keep the 83P and the SE
compatible, but in the long term this may not be the case. Good examples:
The SE has 196K of Flash ROM space reserved for additions to the operating
system. These additions couldn't be used on the 83P. Also, the SE has an
extra 96KB of RAM that the 83P doesn't have. It seems like sometime in the
future the two are going to diverge.
-There's no RTC on the board, where could it be?
...Quite a few things seem to be combined into that "TI REF" chip. For
example, the CPU, and LCD Controller (link hardware as well?). It could be
handled by this chip as well.
Thanks for any thoughts!,
-Dan Englender