Re: TI-H: TI Modem

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Re: TI-H: TI Modem


> Grant Stockly wrote:
>
> >Instead of having to access the link port (at 36 kilobits baud or whatever it
> >is) a chip can be hooked up directly to the CPU of the TI92 (through the ROM
> >expansion module) and be accessed at about a megabyte a second (I BELIEVE, may
> >not be quite that fast.  It also depends on the software used to read the
> >data.)
>
> You can get it to 5k a second through the link port.
>
> The 68000 at that speed can do ~8MB a second.
>
> >on a normally clocked TI92.  This would require only the chip that you
> >need to access with no serial interface.  It's cheaper (you don't need a
> >serial
> >interface), simpler (you don't need program in all the serial stuff, you just
> >copy a memory location) and a whole lot faster (already discussed).
>
> Sorry,
> You're going to have to do more than just write to a memory location.

I have no clue how the network chip works (although I am very interested).  But
from what I can tell, you just read from the buffer, right?  Can you not map the
buffer as memory?

Using a 10 MHz chip, that would give a 2.5 MHz bus speed.  The chip has to read in
the instruction which will take 1 to 2 bus cycles (not sure, didn't check), then it
has to copy the information taking another two bus cycles.  At 16-bit, that is
about a megabyte per second, using the most efficient code that I know of (I'm not
a programmer):  move.w (a0),(a1) over and over for the size of the buffer.  That is
not 1MB per second access speed, but 1MB per second copy speed.  Just out of
curiosity, where do you get 8MB?

That's a lot more than 5k per second either way  (Yes, 36 kilobits is about 5
kilobytes per second.  4.5 actually.)

I understand that every calc has a link port, but the way I see it any of these
fine people on TI-hardware who want to network their TI92 would most likely be
willing to do a modification or if they own a TI92 use the ROM slot.  Heck, why not
just put the chip IN the TI, and then add a network socket on the side or
something?  This isn't a commercial product or anything, it doesn't need to be
adaptable to every TI in the world, just those who want it.

--
-Calan

Chris Lambert
clambert@ieee.org
Member of Geneva College Student Branch IEEE
Head of Marvin Robotic Development Team
URL:  www.geocities.com/SiliconValley/Peaks/6869
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