[chirp_users] Are CHIRP img files are always backward compatible?

[Tom Hayward]

On Sat, Jun 3, 2017 at 5:51 AM, Rich Messeder <NE1EE at hotmail.com> wrote:
> For each new release of CHIRP, should I read a new file from the radio, open the latest saved file, and copy memories to the new file?
> The issue prompting this is that I wonder if CHIRP img files are always backward compatible? Sometimes compatible?
> What is the 'best practice'?

Chirp img files are a raw memory dump from the radio. They may change
with radio firmware version, but they won't change with Chirp
versions. In fact, if you download from the radio, then immediately
save the img, Chirp will not have touched the data at all. It will be
a bit-for-bit clone of the radio's memory.

New Chirp versions my *interpret* the img differently. If we find
there was a bug in how a radio's data was being interpreting, a new
version of Chirp will contain a bug fix to interpret the data
accurately. This would not necessitate downloading from the radio
again (unless the earlier Chirp version clobbered the file due to a
particularly horrendous bug).

I tend to make changes to my radios "in the field". I might add a
channel from the front panel, change a scan mode, etc. To not lose
these settings, my "best practice" is to always Download From Radio
before editing with Chirp. This makes sure any changes I make with
Chirp are on top of my "field" changes, not replacing them.

Tom