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Should we have a SD card slot in the calc?
Yes
 66%  [ 8 ]
No
 33%  [ 4 ]
Total Votes : 12

willrandship wrote:
Ever heard of Bit-Banging, also called Bit-bashing? It's a concept which allows you to access SD data, and write to SD, with only standard IO pins. It's also why you can make hardware that goes into the sd slot, that isn't a storage device.

So, SD is good after all? Yay! No need for usb then, right?
Well, you've oversimplified the concept of bit-banging pretty momentously, but in the end, yes, accessing the SD card directly via I/O pins instead of from a dedicated host controller is indeed bit-banging. Then again, every TI-83/83+/84+ peripheral project like my networking projects with CALCnet, Ben Ryves' Emerson library, my own TICI attempts and PS/2, and QuadPlay / mobileTunes 3 / all other sound programs for the calculators are just bit-banging. Smile
Yeah, you people know much more about it than me Razz
willrandship wrote:
Yeah, you people know much more about it than me Razz
That's not necessarily true, and even if it is, there's no reason for you to not still learn from us and inject your own ideas and opinions. Smile
I still think USB is good Smile SD card is nice too, but you will definitely need a controller + FAT32 drivers.
alberthrocks wrote:
I still think USB is good Smile SD card is nice too, but you will definitely need a controller + FAT32 drivers.
A controller for the SD card? Not necessarily, if we go with a bit-banging approach. Did you miss the idea of bit-banging, or did you dismiss it as inefficient or implausible?
Just didn't read the whole thing. Razz
Good idea tho
alberthrocks wrote:
Just didn't read the whole thing. Razz
Good idea tho
That seems to be a common problem with you. Wink Just Joking The downsides of the bitbanging approach, of course, are that (1) it requires more thought from the CPU, and (2) that it takes up data lines that could otherwise be used for something else. I assume if we use the eZ80, we'll need a bus arbitration chip, like the one that was in that custom ASIC in the 83+s and is now part of the CPU/RAM ASIC in the 84s?
Bit-banging still doesn't solve the issue of licensing, or did I miss something where we are able to get around that? Also USB would allow for using SD Cards, as BrandonW has done so with MSD8X and USB SD card readers, though it did require extra power.
TheStorm wrote:
Bit-banging still doesn't solve the issue of licensing, or did I miss something where we are able to get around that? Also USB would allow for using SD Cards, as BrandonW has done so with MSD8X and USB SD card readers, though it did require extra power.
You missed where BenRyves pointed out that there are some free and open specs for SD things for many circumstances. Smile And that's true about USB, although you'd then need to write the appropriate USB drivers.
KermMartian wrote:
TheStorm wrote:
Bit-banging still doesn't solve the issue of licensing, or did I miss something where we are able to get around that? Also USB would allow for using SD Cards, as BrandonW has done so with MSD8X and USB SD card readers, though it did require extra power.
You missed where BenRyves pointed out that there are some free and open specs for SD things for many circumstances. Smile And that's true about USB, although you'd then need to write the appropriate USB drivers.
Well yes, it would require someone writing USB8x+MSD8x equivalents for this calc. Its good to know we can use SD card without paying out the a.
Definitely. Did anyone spec out how much the physical socket would cost? Sparkfun has an SD/MMC card socket for $4 each, so I'm sure we could pay $3 or $2.50 in quantity and from a cheaper supplier.
KermMartian wrote:
Definitely. Did anyone spec out how much the physical socket would cost? Sparkfun has an SD/MMC card socket for $4 each, so I'm sure we could pay $3 or $2.50 in quantity and from a cheaper supplier.
What about micro SD to save on space in the case? Its not microSD cards aren't hard to find these days.
TheStorm wrote:
KermMartian wrote:
Definitely. Did anyone spec out how much the physical socket would cost? Sparkfun has an SD/MMC card socket for $4 each, so I'm sure we could pay $3 or $2.50 in quantity and from a cheaper supplier.
What about micro SD to save on space in the case? Its not microSD cards aren't hard to find these days.
Don't you find them more expensive for the capacity? And I'm always afraid I'm going to break them or lose them, since they seem so small and fragile. I feel a calculator that might be used by school-age students needs something less breakable and more robust.
microSD cards do not have to implement the SPI/MMC mode (though all of the ones I've tried do) so they may not work.

As for sourcing sockets for SD cards, I bought a cheap card reader from a pound shop (so costing 1) and desoldered the connector. Much cheaper than buying the sockets individually, though requiring a bit more work. The contacts on SD cards are spaced 0.1" apart, so it's relatively simple to make your own connectors too.
I pay the same for a 2G micro as a 4G regular. I only like to use them in more permanent storage, like my DS Flashcart. Reg SD is much more durable.

http://www.mouser.com/ProductDetail/3M-Electronic-Solutions-Division/SD-RSMT-2-MQ/?qs=sGAEpiMZZMtaouNQoacPIDlbfnt3p4I4itkBBeOC%252bPc%3d

Here's a nice, cheap SD connector, $1.30 for 1! $0.89 for 500!
I assume you mean $0.89 per unit for 500.
merthsoft wrote:
I assume you mean $0.89 per unit for 500.
Indeed. Smile Willrandship, ah, that's even cheaper than I was expecting from Mouser. BenRyves, that's my strategy to get cheap USB sockets as well, except here in the US we go to $0.99 stores. Smile
That's all folks! Smile Voting is now closed, and votes will now be tallied.
The final feature list will be announced soon, so stay tuned.

Thanks to everyone who voted! Very Happy
I believe the overall verdict was a bit-banged full-sized SD card slot here?
  
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