Re: TI-H: Parallel Memory expansion

[Prev][Next][Index][Thread]

Re: TI-H: Parallel Memory expansion

>First off, Does that mean Mel Tsai is not going to be working on ANY
>more expanders? (Though perhaps I should ask him.) 

The Expander II and III are both in development right now, and should
be available within a few months.


>I also found another
>8Mbit serial FLASH memory chip, almost exactly like the Expander SF's
>(Except it isn't a MicroWire bus, so new software will need to be
>written.)
>But an I2C converter to parallel data would be nice since you could
>daisy-chain to other I2C devices. This would allow the TI-85 to manage
>the collection of vast amounts of information from various sensing
>equipment, and while I will construct a schematic for the 8Mbit flash
>chip, for anyone who wants to write software for it, I personally feel
>that the I2C system (albeit noticeably slower and larger than the flash
>chip) lends itself to more uses than just storing Zshell games.

Yes, there are two new places that are selling high capacity serial
flash EEPROMs but neither are easy to interface to and neither are
compatible with the current schematic.  There is a two-wire 8Mbit
flash chip coming out in like 5 months from this place, but I probably
won't use it if it's expensive.  The others are all SPI bus which
means a minimum of 4 wires are needed (5 or 6 are preferred), whereas
the TI only has 2.  That is why a microcontroller is the easiest way
to go, and it also allows you to do a lot of cool stuff :).

And yes, the new expanders will probably still be using serial flash
EEPROM chips since they are convenient to access and have low
pincounts (these upcoming ones are cheaper, too).  Using a parallel
eeprom, while technically more prevalent in the semiconductor market,
are significantly more difficult to access because an 8Mbit parallel
EEPROM requires over 32 chip connections (8 data lines, 20 address
lines, minimum 4 control lines)!  That makes for a very complex
printed circuit board even with a microcontroller.

-Mel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The TI-Memory Expansion Homepage
-http://www.egr.msu.edu/~tsaimelv/expander.htm
Follow-Ups: References: