... yours is apparently for resale...
Not necessarily. It would depend on how well it worked out. But it's easier to justify if I approach it as a commercial product. And, if I make a good enough case for it, I might be able to talk someone I know into putting up $$ for the equipment (ie, etching kit, eprom programmer, etc). Otherwise, I might have to do most of it -completely- from scratch. (DIY eeprom programmers are all over the net)
My thoughts about this run sorta like this:
We Know it CAN be done. No One has shown a commercial product, though. We've seen carts for the various systems produced by homebrew devs, so, why not the pce?
Well, the first problem is cost; to even get it off the ground, you need an eprom programmer, some way to create the pcbs, and the parts. It might be neat to do for fun or research, but if its going to be 'commercial' it would have to be done at a very low cost.
Low cost doesn't necessarily mean cheapest possible, but it does mean I have to minimize cost. That implies that getting someone to produce one-off proto boards is out - even assuming really good pricing, based on your figures, it's still about $5 a board. And after our experiences with getting CDs replicated, we're pretty leery about using outside people for production. That's why I was asking about etching the boards myself.
As for the boards themselves, I figure we would need a couple of dev boards, using UV Eproms; Say 5 for
easing the calculations. A 256Kbit EEPROM like that runs around $5.00. But, once the code is working and tested, we can switch over to OTP EEproms, and cut that cost down to about $3.00 each.
And yes, sockets are a necessity! (I've blown too many chips by overheating them, in a hurry to get the circuit built. Sockets help prevent such disasters ) So are pin-compatible parts.
I didn't see much else on the board you built; If we figure $10.00 for complete parts to do it all (per board, and yes that's probably overpriced), and another $5.00 for the pcbs (again, probably overpriced) we're looking
at $15.00 per board.
Well, you get the idea, I hope. It cost about $600.00 to get insanity pressed; I figure I could do this, even buying a 'cheap' eeprom burner for that amount. So, assuming we make 20 cards, they would have to sell for
$30.00 each, which I don't really think is overpriced, to cover our investment. (And probably make a profit at that). So it's definitely economically doable. I just have to convince a couple of people to come up with the money :-)
As for the hardware side of it, I can see why you chose the eeproms you did. Almost all of the signals are straight runs directly to the chips, especially if you reverse the traces ala the JP pce. I -think- If I go with
a double-sided board, I can reverse the data lines 'underneath', and make a dual us/jp board. And, if I split the address space in half (we are using less than 1/2 of the available), I can add an inverter on A20 to select the
chips: upper half would be RAM, lower would be ROM. Not an ideal solution (and probably not for the first cards), and something to think about for later, but definitely doable.
My plans would be to take the cycle demo Aetherbyte has, burn it on a UV-EPROM (In case it doesn't work), and use the dev boards to make sure the game works, in both US and JP pces. Once we know that that works, and have some experience doing it, we could then start working on a Hucard game, much the same way we are doing with the retro pack. Something simple, but fun.
And then, of course, offer it for sale here, to the people who love the pce. I get the knowledge gained, they get a 'real' HuCard game, and, of course, Arkhan gets bragging rights :-)
edit: I was looking at the chips and their pricing. I assume 70ns would be fast enough (they're not that much more expensive than the 100ns ones). Think those would be okay for High Speed mode? I seem to remember running 150ns Ram in a 4MHz a long time ago, but want to double check.
