[TI-H] Re: building a TI92plus module

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[TI-H] Re: building a TI92plus module

Hi!

> Can you find out that article, please? It would be interesting.
> However I think that protection is not strictly necessary to have it
> working; what do you think?

I don't know for sure where I've found it but I'll keep an eye on it.
No, not strictly necessary but some evil programs might overwrite your FLASH and
that
is not so nice. Even if a program does not intentionally at least an external
switch should
be used to protect some areas (e.g. the certificate's area and boot-strap if it's
inside there)

btw: Has anyone ever experienced the situation of doint an update and it fails in
the middle?
Does the TI get dead (nodisplay, nothing or is it still "flashable"), like some
cell phones.
(e.g. N*kia's have there boot strap in the DSP itself so they r always updateable
but Slemens
is really delicate and sometimes extremly bitchy :-) but that's off topic, so I
stop.

> > If u can find out the pinout of the connector also let me know. It might
> > help.

This will be really interesting. The RAM on the (non-plus) module will reveal
at least the adress bits and the data bits (at least 8/14 of them).
but there should be also some control signals like _ALE, _WE; _OE
Different access to RAM and FLASH/ROM could be easily done by different
wiring of the address lines.

> There are some informations that I need but I couldn't find: how the
> ti-92 addresses the external rom and ram: addresses and wo4rd length (it seems
> 16 bit words, al long as there isn't a0 and there are 16 data pins, but
> on one of ther previous links there's a 8 bit memory chip connected.
> I'm asking the authors...

As far as I remember ther's a MC68ooo inside (or emulated?) This processor does
not necessarily need a0. The 68k has a LSB and USB (lower and upper significant
byte)
Pin to indicate which half of the 16bit wide word at it's data bus is needed if in
byte mode.
(e.g. move.b    #0,12345 should access adress 12345 which is odd. but the databus
will read
@12344 and will signal the USB).

The clou will be to find out all the control signal. There r a lot of pin at the
connector.
Also interesting point to start is the pattern on the PCB where a IC could be
mounted and
soldered. (I assume it has been used in the TI-92 without the possibility to hold
the add-on
plus-module (maybe an earlier design or so).


Pierre
References: