Re: TI-H: Parallel Memory expansion
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Re: TI-H: Parallel Memory expansion
Thomas Goetzman wrote:
> The schmatics I've seen need 3 wires, a Clock, data, and the ground,
> which the TI-85 can do just fine.
Is this a parallel chip or isn't it? If it is, I'd love to see an
interface
circuit... if someone has a parallel chip working with the calc
directly,
a lot of things would be easier for the end user of an Expander style
product.
> And I must disagree on your opinion about Microcontrollers. A
> Microcontroller such as a PIC is unable to address memory, which equates
> to a large amount of code. And who has the equipment to program a PIC
Huh? I have serial flash EEPROM routines and TI protocol send/receive
routines coded in under 200 instruction words on a PIC16F84. Code
size is almost irrelevant IMHO, since A) most hobbyists will not be
burning their own MCU and B) as long as it fits in the MCU's internal
ROM/EEPROM, it doesn't matter how large it is. ;-)
I'm still not sure what you meant about addressing memory... do you
mean an external RAM chip or something along those lines?
> microcontroller? Other controllers, such as the Z182, used by one
Actually, I have seen two transistor programmers for the PIC, which
connect via a parallel port and are programmed with hobbyist code
availible for practically every OS (DOS, unix, OS/2, etc). You
could probably build such a device from Radio Shack parts for under
$5. This would only work with Microchip's serially programmable
parts, which most of the worthwile parts are, anyway. <Gee, I wish
I had known about that before I spent $100 on the SimmStick
programmer :| >
> expander require more external circuitry, and is itself more powerful
> than the system it would be "serving".
Yes, Cliff Biffle's expander is perhaps guilty of overkill. But you
still have to admit, a Z182 controlled Expander would be majorly
cool. :-)
> Detailed/Computer aided design of the PCB can help keep the placement of
> parts simpler. Also, I plan to sell pre-etched PCB boards (Perhaps with
> the Surface Mount FLASH chip soldered on allready.) So the person can
> solder the simpler DIP chips and connect the cables, etc.
Hmm, as I said above, I'd love to see your schematics, if you've posted
them.
> I'm not really arguing for either side, they both have drawbacks, I'm
> just saying that Parallel FLASH chips can be used without the need for
> microcontrollers.
Again, I'd love to see how. If I am sounding sarcastic, I don't mean
to be... its just that I have assumed for a long time that using
a parallel EEPROM with a 2 wire calc l/p is damn near impossible.
Regards,
Bryan Rittmeyer
bryanr@flash.net
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