points by DonHopkins 6 years ago

Speaking of weird retrocomputing BASIC features, does anyone know why DECSYSTEM 10's and DECSYSTEM 20's BASIC had a "LISTREVERSE" command?

Yes, it actually did exactly what it sounds like!

Chalk one up for DEC and BASIC. What other programming languages support that feature, huh?

Now all you need is a COMEFROM and COMESUB and RUNREVERSE (or NUR) statements, and you can write reversible BASIC programs!

https://en.wikipedia.org/wiki/Reversible_computing

https://en.wikipedia.org/wiki/Counter-Clock_World

https://imgur.com/a/Bt40M

    DECSYSTEM 20 BASIC User's Guide: LISTREVERSE command

    LISTREVERSE
    LISTNHREVERSE

    LISTREVERSE and LISTNHREVERSE print the contents of the
    user's memory area in order of descending line numbers. 
    LISTREVERSE precedes the output with a heading,
    LISTNHREVERSE eliminates the heading.

    LISTREVERSE

    EQUIV             10:53                      13-NOV-75

    40    END
    35    PRINT "THE EQUIVALENT CURRENT IS",I, " AMPERES"
    25    I=E1/R
    10    INPUT R
    5     INPUT E1

    READY

http://bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-1...

http://bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-2...