> not sure yet if I'd have to write in pages, or if individual bytes
> are writeable.  With an SD card, the mechanism is in place
> already to handle these

I'd not assume that. In 4-bit mode, yes. Not sure whether all
card O/S functions are working in SPI mode

If you can use a PIC with 512 bytes or more of spare RAM then
that allows you write a block to SD as well as receive incoming
data bytes to be logged, ie ping-pong buffering. 1kB/s writing is
not an issue, way below card capability

> Total write cycles of 100K (or even 1/10 of that) is fine

16GB or more gives you the option of splitting the card in two, to
spread the write cycles around. Because of my bad experiences
with Read Disturb I would hesitate to use a FAT system, eg/ie an
O/S that requires a path through a boot sector or directory, as that
could mean excessive reads of a few blocks when accessing data
files. Absolute block addresses can be used. A record could be
held in the PIC's EEPROM or Flash, which itself would need a
wear management system, as the numbers are approaching the
write endurance

An SD card is in theory probably the simplest and most economic
option, but be wary of knock-offs and big numbers of writes to
large capacity ones. The cell size is getting incredibly small and
much more prone to errors. The majority, I'm sure, are made for
applications (cellphones, cameras etc) which will never see 100k
reads or writes, so the typical consumer will not experience any
degradation

Joe


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