16 Jun
2015
16 Jun
'15
7:25 a.m.
Choosing the larger card is, IMO, the right answer because you don't
actually waste the space, you extend the life significantly because the
wear leveling will spread your 256K across the entire flash region.
The larger that region, the less often you re-write the same cells,
thereby extending the life of all the cells.
Chris
On Monday (06/15/2015 at 03:06PM -0700), Mark J. Blair wrote:
--
Chris Elmquist
On Jun 15, 2015, at 14:56 , Dave G4UGM
<dave.g4ugm at gmail.com> wrote:
A friend of mine refused to buy modern SD Cards because there was no way he
was going to fill them. Trouble is that although smaller SD cards were
available they were way more expensive (being discontinued and therefore
rare and valuable).. He struggled with buying a larger card only to waste
most of it, or buy a smaller one and waste his money....
I had that same mental hangup when thinking about how I might design an SD card based
TU58 emulator in the same form factor as a TU58 cartridge (still on my to-do list, by the
way). How was I going to implement the user interface? It's not like there's much
room for an LCD or buttons on the edge of a TU58 cartridge. Then it finally hit me: SD
cards are cheaper than TU58 cartridges ever were. So why not just use the first 256k,
ignore the rest of the card, and swap cards exactly the way one would swap TU58
cartridges, with one image on each card? Yeah, 99% of the card is "wasted", but
they're presently cheap and plentiful enough to ignore that.
Ok, I might actually have the emulator read a file from a DOS filesystem rather than
using the first 256k of raw blocks. But it'll probably just be a fixed filename with
no controls to select a different one, and the expectation that an entire (cheap,
plentiful) SD card will be devoted to each tape image. At least this way, other things can
also be on the card, so it doesn't need to be wasted if not needed.
Your friend should understand that the larger card that he would be "wasting"
probably has less silicon in it than the older one with less capacity. The cheapest card
that is reliable, fast enough and large enough for his task is the best one to get, even
if it's much larger than he needs. Just one of the weird parts of the Moore's Law
curve!
Hmm, this reminds me that back in the day, floppy disks were expensive. We have it easy
with cheap and plentiful SD cards nowadays. But maybe my perspective is different as an
employed adult rather than a teenager with limited funds? Anyway, SD cards seem to be
cheap enough to be nearly disposable nowadays.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/