I started to do this because I wanted to show off more than one program
on the Hydra, and it is in a few ways easier than I thought. The book that
comes with the Hydra almost explains this but leaves out a few details
that I will fill in. It is much simpler than I thought.
It will make it much cheaper for you to share games you make for your
Hydra, and it seems to be OK (as in legal) and very convenient to do this.
What is shown here is not one but several game memories in various make stages.
Step 1: Things You May or May Not Need...
You will need more serial flash chips.
Although 24LC256 and 24LC1024 are mentioned by the author of the Hydra manual,
I've used 24LC512, which has 64K of bytes on it.
Almost all of the hydra software I've seen runs in 32K,
and therefore which ever chip is most readily available
or cheapest is recommended. Also recommended is getting DIP chips instead
of surface mount if it's available, even if they cost a little bit more.
You can obviously use up your experimenter's card to make another
game card, but I saved mine. You can easily etch a single sided board
or not even etch it. I had a stale bottle of ammonium persulfate that did
not etch, so I cut away the excess copper with a dremel tool after etch failure.
(Note to self: Ferric Chloride etchant has a much longer shelf life.)
The boards can be single sided because all of the pins used for memory
are on the back side of the board.
You don't even need to be plugging any boards into the cartridge slot.
You can simply turn off the Hydra and replace the 24LC1024 that is
socketed on the motherboard with any of the above chips, and load
games or programs into the replaced chip.
HAZARD: Pins breaking off. This problem can be avoided somewhat
by putting the chip into another socket, especially one with hard round pins.
HAZARD: Plugging the chip in backwards. "If" this is likely to happen, label
the chip with an arrow (and also some clue as to what program might be
on the chip, even perhaps by labeling them, like #1 ... etc.).
HAZARD: Be sure to turn off the Hydra when changing the chip on the
motherboard. The cartridge slot is designed to be hotplugged, the
chip socket on the motherboard is not. The Propeller is a 3 volt chip
that may be very static sensitive.
Needed: more flash chips
Needed for best results: usable boards or equipment to make them
(etchant, permanent marker, soldering iron and solder, drill or dremel,
safety glasses and gloves or do at your own risk...)
Needed to protect memory chips plugged into motherboard:8 pin dip/dil socket or pin header with hard round "machine" pins. I cut the green one (16 pins) in half.
(and insert them correctly with the help of labeling)