potatohead's Blog - What's the general opinion here about hardware

RSS Bot · October 24, 2006

Addons?

Got my demo board today. It's a fun little beasty. Actually I've a coupla questions:

Anyone care to comment on the video in capability of the 7800? Let's say I generate a NTSC signal and insert it. Assuming the necessary timing information can be provided by the 7800 (CPU maybe?), is this an overlay, meaning I can generate my own video on top of what the 7800 already does?

The chip I'm tinkering with has onboard timers and video generation. (Composite video only takes a coupla resistors.) Thinking of an interesting blend where maybe I don't do much with the 7800 Maria chip and have the propeller chip do video generation or maybe just sound, like adding a POKEY currently does. Lots of fun possibilities that appeal to me because it would be both a hardware and software project.

The end result would be programmable and not too expensive to replicate either as very few additional components would be required.

My other question is along the lines of why bother? Is this going outside the classic computing aspect of things too much? I personally like the older hardware because of the kinds of games created. There are enough limitations to force the kinds of games I've always loved. This little project would very likely not exceed that boundary so much as to reset expectations beyond those in the norm here. Opinons?

On the off chance that this idea sees some real hardware, how do you guys figure out what a target price would be?

I know the core chip is the $14.00 or so. 5 resistors, maybe a buffer chip to handle the 3.3V to 5V conversion will cost some smaller amount, maybe a coupla bucks total. There is an on board timer that I don't know too much about yet, but would probably suffice to eliminate the need for an external oscillator. The 7800 could provide a baseline for programmers to assess what their particular timing variance is. The only real issue would be peak compute. Some kits would run faster than others, but all would run at a more than acceptable minimum.

32Kb of RAM is onboard the propeller. Looks like I would need a cheap eeprom and socket for that too. 32Kb minimum.

If I were to use the 40pin DIP package, a socket would be all that is needed to mate the chip to the board, thus making kits a viable option.

How much are custom boards and who might make them?

Programming happens via USB or serial. It would also be possible to feed data through the 7800 itself, but that has a lot of development issues. Programming components can be put on board, or an inexpensive adapter from the producers of the chip is available. The chip has onboard ROM that can communicate with a PC and can program the eeprom. One could just program it themselves too...

Too many components to be viable at all?

Thinking of three potential options:

Fully assembled, plug and play board, with USB programming cable.

Partially assembled board, with core components soldered, and a kit bag of goodies or let user aquire own or use stock.

Completely unassemblied kit.

I'm just musing right now, trying to consider what I might use this great little chip for. An early idea of price and hassle might tell me right away if this is not a direction I should go for anything other than personal reasons.

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