Re: TI-H: General questions with a possibly big impact.

[Prev][Next][Index][Thread]

Re: TI-H: General questions with a possibly big impact.


>Alright.  These questions are about the internals of the TI-85
>calculator.  if things turn out, it could be a huge thing.  I don;t know
>if they would be the same on the other calcs, but it is very likely.
>
>Anyone of the questions you can answer would be very helpful:
>
>1) Is the RAM on the calc Dynamic or static?

Static, otherwise it wouldn't be battery backed (although certain
types of dynamic ram CAN be battery backed, despite what others may
tell you :).

>2)  To the person who drew the schematics: how did you get your
>information about the pin names for the tga43 chip, and the others?

Pin names were mostly figured out via the SRAM chip whose pinouts are
JEDEC standard.  The rest of the pins were either straight guesses or
not listed.

>3)  The processor is either a CMOS or NMOS version, does anyone know
>which?

NMOS processors are never (or, at least very rarely) designed and sold
anymore.  Besides, from a user's perspective, it doesn't matter what
process it's manufacturered under, the pinouts and performance would
be identical.

>5) the TGA43 is either a direct adaptation of the z80 by TI, or it
>actually contain sthe Z80 chip manufactured by Zilog and surrounded in
>the TGA43 by the TI-85 system logic stuff.  Does anyone happen to know
>anything about this? for instance, if i had an old chip, i could take it
>apart and see some things inside, like if its a hybred chip or not.

Multimodule chips like you're speaking of are rarely found in cheap
consumer electronics.  The chip in the 85 is most likely a single ASIC
with a completely redesigned Z80 core and integrated peripherals,
likely made by toshiba.  In fact, I doubt that it's even a Z80 at
all... It's probably a cross between a Z80 and the redesigned Z180
which has a built-in MMU, although it would be just as easy for them
to design the glue logic necessary to address greater than 64k.

It would be virtually impossible (without extensive help from the
people who designed it) to build a TI-85 compatible uP out of an
original Z80 chip and some support logic.

While zilog still sells pin-compatible Z80's (although they're static
HCMOS now, not the power hungry NMOS crap of the 70's), they no longer
"own" the market on Z80's.

>6)  does anyone know if any of the unknown lines out of the processor
>could possibly be the /IORQ line?

>From a hardware perspective, it's likely that none of the original Z80
control or status lines are brought out to the MCU package pins inside
the TI-85.  And besides, even if they did bring out the /IORQ line,
it's unlikely that you'll find any unused I/O space within the memory
map because I have a sneaking suspicion that they didn't implement
more than 8 I/O ports as opposed to the Z80's original 256.

>Also, ive been out of touch with the net community lately, so is the
>Radio Link Grant was working on finished yet?

Hehe :).

>And, is the EIII doen yet?  where can i get information on the EIII (or
>EII or whatever you want to call it)

'twas dropped a long time ago.

>All the current expanders and communications networks are slow by
>definition, because they must operate throught the serial interface
>provided by TI, or another serial interface (such as the SPinTerface
>Port).  If these questions turn out the way i want them to, we could
>have infinite IO devices operating at 8bits.  they can work at processor
>speed and do whatever we want.  Anything is possible with this.  I hope
>you see the ramifications of this power, but if not, please try to
>answer any of my questions that you can anyway, jsut to help me in my
>quest.  Thank you again for any help you can give me,

You are likely barking up the wrong ally.  At one time I had a few
hacks figured out that would allow exactly what you're talking about,
but it's just far too impractical.  First of all, any such
modification would require either an entire PCB redesign or some major
haggling with soldered SMT parts, extra boards, etc.  Who is going to
do this?  The typical TI-H'er isn't going to have the tools nor balls
enough to perform such a complicated mod.

This is why I never really published or talked about the hacks.

-Mel
References: