TI-H: TI Port Doubler & Data/Address bus conections


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TI-H: TI Port Doubler & Data/Address bus conections



>> What if you split teh linkl port and had two things hooked up at
>> oncel.
>> Though you would have to find a way for the calc to know the
>> difference
>> between the two.  What about useing a recive comand.  If it likes it
>> than
>> goto that one and if not got oteh other thing hooked up.  Kind of 
like
>> a
>> port doubler.  I know This sounds easy to me but very hard for people
>> trying
>> to biuld it.

What about having the data alternate between two types, and have a 
simple multiplexer/demultiplexer switch between two devices on each 
clock signal. You would loose half the speed, but the Multiplexer could 
send a clock pulse to the recieving device so it would end up running 
half the speed, but allow two or MORE non-I2C chips or devices. Also, I 
have noticed that I2C chips don't affect the normal transfer. You could 
also use the paralel I2C 8-bit chip to select 1 of 8 dual signal 
multiplexer chanels (2x8 bidirectional multiplexer). The I2C chip 
shouldn't interfere with the other chips transmision.
>
>   Uh; I2C will allow multiple devices on the port; other than that you
>would be talking about a LOT of hardware to do it.
>Does anyone on this list have a clue as to TI's planning upgrades for
>the 92 or not? I know that with the memory cardtridge on the back they
>left the possibility to get more memory etc. Just wondering...
>
>
The Memory cart on the 92 has to have the data AND address bus leading 
to it. If someone knew these, paralel devices could be connected 
directly to the TI-92's data and address bus and you could use the free 
addresses to access those add ons! It would be like all the custom 
devices that people used to build for those old 8-bit computers. One 
idea would be to add a SID chip (like in a Comodore) and a tiny speaker. 
You could set it to an unused address and be able to create wave form 
generated sound of different loudneses and with 3 voices! You could 
probably even add the Universal Bus Extender Card directly with the 
calc!. The UBEC was designed a long time ago, but lets you control 1500 
something I/O ports using only 256 bytes of unused addresses (I think). 
It has Input and output cards and DAC and ADC cards too. You can even 
buy the boards, pre-etched from somewhere.
I suppose it's only an idea, but imagine what you could do with direct 
data/addres access!


Richard Piotter

e-mail: richfiles@hotmail.com

home page: <A 
HREF="http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html">The 
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