
122/136 08 Nov 91 10:30:58
From:   Sam Warden
To:     Yousuf Khan
Subj:   wild blue yonder
Attr:   
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>   [...]         Yousuf Khan
> * Origin: Everyone's flying across the sky, Superman's outta town 

Every time I see this I just about fall off my chair (or worse),
laughing.  I think this is the best tagline on Fidonet, especially
for a moderator, and especially on this echo with its frequent
'topic drift'.

With that in mind, here's an oldie but a goodie.  Please bear with
me; I'm sure someone out there will be seeing it for the first time
(just like how I first saw it).
        ;
        ; enter with four-bit binary 0 - 15 in al
        ;
        add     al,90h          ;feed it a cookie :-)
        daa                     ;abuse BCD codes in a magical way
        adc     al,40h          ;nothing up muh sleeve...
        daa                     ;Presto!
        ;
        ; now al contains correct ascii hex digit 0-9,A-F.  It's magic!
        ;
After I ran across this I played with it for hours, tracing it, trying
to invert it, etc. and studying up on the BCD instructions with a whole
new interest.  This trick has a name: it's called Allison's algorithm.
 
* Sam's *really little* mailreader, version 0.01 *
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 * Origin: ET/PPCUG BBS 503-625-- 7752 or 2421 Intel 9600EX (1:105/201)

