e5frog wrote:
What, are you spending your own money!!?? 😉If you’re short on cash perhaps asking for donations alternatively some kind of kickstarter project or maybe pre paid orders would help.
Of course it’s a lot of work if you haven’t done it before, that’s always the case. Not just the hardware which can take a long long time to CAD when you’ve found the parts you need but all the software as well.
If you weren’t making one I’m sure Richard would have made one by now as he already have most parts of such a project done with FlashBoy and also his Vectrex cart with microSD card reader. I don’t think the market is that big so you probably need all of it yourself if you want to make something from the invested time and money.
Regarding the SRAM issue, already in the 70’s (maybe earlier) they used a battery and two diodes, it should still work… Diode prevents current to flow into the battery, a current limiting resistor could be added to prevent smoke and melting things if there’s a short…
You need a second diode for board VCC to block the battery from powering the whole board.
VCC of SRAM —-|<---- board VCC VCC of SRAM ----|<---- battery + GND of SRAM ------------------------ battery - I was considering using something similar in my Fairchild carts but I decided to try out FeRAM instead which worked out pretty well although they are quite expensive. I saw a RAM cartridge (game copier) for Commodore 64 that worked the same way, holding the memory with a battery. This should hold the SRAM powered for a LOOONG time (if it's a 5V SRAM) http://se.farnell.com/productimages/farnell/standard/42245229.jpg
So what can we do to ramp up your motivation? Not that I have the money right now to get one of these so on my account you can work on it a few more months. 😉
I was thinking if it would be possible to use the CAD:ed connector by one of our members and then try to find the female end of a PCMCIA connector (only the metalpieces that are in the connector) to make proper connectors. The type you have previously linked to worked most of the time on my veroboard built eprom cartridge but it would be nice to have something original looking that works all the time, even if you happen to bump the cart.
With all due respect, I think the wrong thing to do to “ramp up my motivation” is to minimize my problems and condescend me by telling me how a battery and diode works like I’m 5. I realize you are only trying to help, but I need you to understand I am not some amateur who has never built a complex digital board before. I’m an engineer, I do this for a living. I also don’t appreciate the subtle guilt tripping by telling me “Minestorm would have had it done by now”. Especially since I’ve been very vocal from the beginning that I didn’t want to make money on this project and I didn’t want Minestorm to stop any work he was doing. In fact, he can go ahead and make an SD cart right now if he wants. So can you. It can only help the VB community, and I’ve already said I don’t care about making money. In fact, I probably won’t even make back the money I spent prototyping.
The motivation problem comes from the fact that every time I run into a major problem, it usually takes weeks to resolve. Whether it’s a board issue that requires drafting a new board, or a programming issue that I don’t have the right testing equipment to debug, waiting for a new part order, etc., I get grinded to a halt every couple weeks or so and then once I’m not working on the project it is more difficult to resume. It’s just the nature of the beast when one person is trying to interface with obsolete technology from 17 years ago to do things it wasn’t meant to do. IMO the only mistake I have made on this project so far is to dangle a carrot in front of PVB. I did it because I needed information that PVB members already had, but it created expectations. The smart thing would have been to not announce anything, but I had to in order to gauge interest and see if there really was any kind of demand for something like this. If it wasn’t for that, I would have been wasting money on a project that has no future, and I needed to know there is a place for it alongside the flashboy. I am still not convinced of that, but it is what it is.
