Not sure about the checksum.
Wouldn't RTF and FRT end up the with the same number?

It depends on the letter combinations you need, but if there are common letters between the commands, maybe ...
Code:
<font color="#000000"><b>IF </b>chrbuf(0)=<font color="#FF0000">&quot;R&quot; </font><b>THEN
    IF </b>chrbuf(1)=<font color="#FF0000">&quot;T&quot; </font><b>THEN
        IF </b>chrbuf(2)=<font color="#FF0000">&quot;F&quot; </font><b>THEN GOSUB </b>RTF
        <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;M&quot; </font><b>THEN GOSUB </b>RTM
        <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;R&quot; </font><b>THEN GOSUB </b>RTR
    <b>ELSE
        IF </b>chrbuf(1)=<font color="#FF0000">&quot;Q&quot; </font><b>THEN
            IF </b>chrbuf(2)=<font color="#FF0000">&quot;P&quot; </font><b>THEN GOSUB </b>RQP
            <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;C&quot; </font><b>THEN GOSUB </b>RQC
            <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;A&quot; </font><b>THEN GOSUB </b>RQA
        <b>ENDIF
    ENDIF  
ELSE
    IF </b>chrbuf(0)=<font color="#FF0000">&quot;T&quot; </font><b>THEN
        IF </b>chrbuf(1)=<font color="#FF0000">&quot;T&quot; </font><b>THEN
            IF </b>chrbuf(2)=<font color="#FF0000">&quot;F&quot; </font><b>THEN GOSUB </b>TTF
            <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;M&quot; </font><b>THEN GOSUB </b>TTM
            <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;R&quot; </font><b>THEN GOSUB </b>TTR
        <b>ENDIF
    ELSE
        IF </b>chrbuf(1)=<font color="#FF0000">&quot;Q&quot; </font><b>THEN
            IF </b>chrbuf(2)=<font color="#FF0000">&quot;Z&quot; </font><b>THEN GOSUB </b>TQZ
            <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;S&quot; </font><b>THEN GOSUB </b>TQS
            <b>IF </b>chrbuf(2)=<font color="#FF0000">&quot;1&quot; </font><b>THEN GOSUB </b>TQ1
        <b>ENDIF
    ENDIF  
ENDIF
</b>