[TI-H] Re: Inside TI, literally


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[TI-H] Re: Inside TI, literally




At 04:42 2001-08-21, you wrote:
>How similar are the insides of TI calculators. I'm curious if a
>supergenius could take the memory chip from a 83 SE and put it in a
>89.

That is a more complicated question then you might think it is.
The insides is both very different and kindof similar at the same time.
They are similar becasue they are both small computer systems, but 
different because they use completly different architectures. the 68k has 
for example a 16 bit data bus, while the z80 has only an 8 bit.
The memory organization of the 68k and the z80 also differs greatly, but 
this doesn't affect the actual chip, wich is a fairly standard flash chip 
in both calcs.
The greatest problem you would face is probably the difference in data bus, 
wich would require extra hardware to work.
It is also not certain that the SE chip is fast enough for being on the 68k 
bus, specially because it would have to work at double clock speed to be 
able to write 16 bits on one data cycle, since it only can write 8 bits at 
a time.

The answer would in my oppinon be, "Yes, it is teoretically possible, but 
not practical, and not worth the effort"
It is easier and cheeper to buy another flash chip, with more appropriate 
specs if you want to extend the internal flash of a ti89.

In any case you also have to create some new hardware for chipselect logic, 
so it answers on the right memory adresses.
So it would never be just solder out the chip and replace it with another 
chip with higher capacity. You need to change a lot of other hardware too.

///Olle