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https://news.ycombinator.com/item?id=17998940 https://news.ycombinator.com/item?id=17998940 DonHopkins on Sept 16, 2018 | parent | prev | next [–] Speaking of

https://news.ycombinator.com/item?id=17998940 https://news.ycombinator.com/item?id=17998940 DonHopkins on Sept 16, 2018 | parent | prev | next [–] Speaking of weird BASIC features, does anyone know why 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? 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://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/DEC-20-LBMAA-A-D%20BASIC%20User's%20Guide.pdf http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/D...

reaperducer 1y ago
When you want to see the beginning of the program, but the terminal you're using is too laggy to send ^S in time to pause the listing?
- JdeBP 1y ago
  Unlikely. LIST and LISTNH took an optional line number range.
rootbear 1y ago
All I can think of is that it was a way to look at the end of a long program which wouldn't all fit on a display. Predating, I suppose, the 'tail' program, or whatever the DECSYSTEM 20 equivalent was.
- leoc 1y ago
  I assume that it would be clearly useful if your terminal was a slow paper teleprinter. Once you got used to reading listings with the lines in reverse order, which shouldn't really be very difficult, LISTREVERSE would let you start reading from wherever you had got up to in your partly-completed listing, then cancel whenever you'd got enough context, instead of having to guess in advance how far up the program you'd want to look. You could even then print out the same range of lines again unreversed, if you wanted.

reaperducer 1y ago

When you want to see the beginning of the program, but the terminal you're using is too laggy to send ^S in time to pause the listing?

JdeBP 1y ago
Unlikely. LIST and LISTNH took an optional line number range.

rootbear 1y ago

All I can think of is that it was a way to look at the end of a long program which wouldn't all fit on a display. Predating, I suppose, the 'tail' program, or whatever the DECSYSTEM 20 equivalent was.

leoc 1y ago
I assume that it would be clearly useful if your terminal was a slow paper teleprinter. Once you got used to reading listings with the lines in reverse order, which shouldn't really be very difficult, LISTREVERSE would let you start reading from wherever you had got up to in your partly-completed listing, then cancel whenever you'd got enough context, instead of having to guess in advance how far up the program you'd want to look. You could even then print out the same range of lines again unreversed, if you wanted.