"Just what is an Add-on Board?"
Well, it is a board that is installed inside the Zipit and gives us
several improvements over a stock unit:
Adds RS232 Serial Port.
Adds an MMC card for storage / bootup.
Adds an EL Backlight power supply.
Allows easy updating of the Flash memory contents.
TopRS232 Serial Port
First benefit, the serial port. With it you can now use either the 802.11b
WiFi or RS232 to pass data in & out of the Zipit. This is not the type
of serial port that you would use to connect to an external modem. There
are only three signals on this serial port: TXD (transmit data), RXD
(receive data), and Ground (common). However, this is not a TTL or CMOS
voltage levels that are used here, but good old RS232. You can connect
the Zipit directly to your computer by plugging it into the computer
This serial port is how we update the Flash memory (see below).
TopMMC card for storage
Once we get "our" linux inside the Zipit, we quickly find out that
there isn't much room at all inside that 2 Megabytes of Flash Memory.
So, the MMC socket allows us to use these cheap camera NAND Flash
memories to greatly boost the file space. Having a removeable "hard drive"
in the Zipit, you can easily move data in or out of the Zipit.
Just a note to allay your fears and confusions, I did say "MMC" and not
"SD", didn't I? Well, let me explain: Yes, you can use either the
miniature MMC or SD card in this socket. No, you may not encrypt the
data on the SD card, this socket is not capable of allowing that type
of special electrical wiring and use. However, you can use an SD card as a
plain old MMC card and it works just fine!
TopEL Backlight power supply
This probably generates me more email than anything else, people want
someone to install the EL Backlight itself. Well, I decline to offer
to do this for them with the explanation that it takes several hours
to add the actual backlight. Labor costs and for the price of that
labor, you can buy a cheap Zaurus PDA on ebay!
Having that said, the Add-on Board does have the necessary EL power
supply on it, and it will be tested to ensure that it works. YOU
will have to be the one to do any addition of an EL Backlight. I do
give you a tested supply on the Add-on board.
TopUpdating of the Flash memory
In my opinion, this is one of the most exciting, and empowering, aspects
of choosing the Add-on Board! You may now safely replace the contents
of the Flash memory without fear of bricking the unit. If you mess
something up; you can simply do it over again!
The miniUSB (Type B) connector has the necessary RS232 signals for
uploading a new kernel image and filesystem. This connector also has
the DEBUG signal there so that you can ground that wire and place the
Zipit CPU into a download (external programming) mode.
With the serial port + DEBUG signal, you can now build and customize
your own linux kernel and filesystem (use the buildroot to do this). Or,
you can take someone else's images and put those into your Zipit.