Icom IC-R2 memory

Here are some observations about the Icom IC-R2 radio's memory that might not be in Blakkekatte's (broken link) paper.

Don't allow the user to program non-stepped intermediate values

(This item concerns writing computer programs to program the R2.)

Let's look at the way the following fractional megahertz are stored in the 6th (i.e. final) nibble. "142006" in memory will be seen as 142.00625 on the radio screen, with the 25 in small figures.

0.00000 0
0.03125 1
0.01250 2
0.04375 3
0.00500 5
0.00625 6
0.03750 7
0.01875 8

One wonders if the radio's tuner actually tunes to that value as seen on the radio's LCD, or in fact just the truncated value. In any case, a programmer when reading a memory location that ends in a 6, must put a 625 etc. on the computer screen, and not a 600 etc., in order to properly mimic the radio.

We see that there really isn't much room to let a user program between-step frequencies that he couldn't get into the radio without extra help. (Using perl -e 'use integer;for($i=0;$i<10000;$i++) {if (!($i%625&&$i%500)){printf "%02d ",$i/100;}}',) one can see that memory ending in 00 05 06 10 12 15 18 20 25 30 31 35 37 40 43 45 50 55 56 60 62 65 68 70 75 80 81 85 87 90 93 95, a total of 32 of the possible 100 items can get into the radio's memory without external aids. (I'm talking about other than the AM broadcast band on 9khz step models). Many of these get mapped to the little 25, 50, 75 we see on the LCD.

One wonders how the radio will show a final 4 or final 9, or 01 02 03 etc. (somebody else try it first.) Anyway, should we let the user program e.g. 17 for .017 and 19 for .019, when 18 gets mapped to .01875, at least on the LCD and hopefully in our programs' displays? No, I say we should stick to the safety of numbers one could get into memory with just the radio itself.


Dan Jacobson

Last modified: 2010-01-05 02:59:42 +0800