Thank you for the reply.
I'm just beginning the sketch.
I'm working on a log for amateur radio contest (if it is useful to know): during the competition the log is filled (in a SD card or a USB pen, what is the easiest way). Then the log is downloaded into a PC for its arrangement and mailing to the contest committee.
Each record has the following data:
1) transmitted serial number (001, 002, 003, ... up to 999) - automatically incremented by software after the input of the previous record has been completed;
2) received callsign (10 alphanumeric digits, A..Z, 0..9 and slash /);
3) received report (3 decimal units, e.g. 599);
4) received serial number (3 decimal units, like pos. 1);
5) received geographical locator WWL (6 alphanumeric digits - 2 letters, 2 decimal units, 2 letters);
6) time at end of record input (hours and minutes).
Except for pos. 1 and 6, all the data are inputed by keyboard.
Even if 999 records are out of imagination, 200-300 records are a realistic in a good contest scoring.
Meanwhile, a second data base is filled with the inputed callsign and related geographical locator(s), so that they can be suggested during a new contest.
Thank you in advance.