What good are vertical tab and form feed for ?

[Spiros Bousbouras]

The fact that vertical tab and form feed exist both in the
basic source character set and the basic execution
character set suggests to me that there is a class of display
devices where vertical tab and form feed produce a predictable
and consistent (among different devices) behaviour. So what
are these devices and what is the behaviour ?

For old printers , form feed presumably moves to the next page
but vertical tab is a mystery to me.

 

[John Bode]

The fact that vertical tab and form feed exist both in the
basic source character set and the basic execution
character set suggests to me that there is a class of display
devices where vertical tab and form feed produce a predictable
and consistent (among different devices) behaviour. So what
are these devices and what is the behaviour ?

Hardcopy terminals and line printers.

For old printers , form feed presumably moves to the next page
but vertical tab is a mystery to me.

Your interpretation of form feed is correct; it moves to the beginning
of the next page. Vertical tab advances the page by several lines
without a carriage return.

 

[robertwessel2]

For old printers , form feed presumably moves to the next page
but vertical tab is a mystery to me.

Mostly OT...

To expand on what John wrote, some (mostly older, and typically line)
printers could have vertical tab stops programmed. On some printers
this was actually done via a punched carriage tape (the tape was a
loop, with holes punched where the stops were desired). Those could
be changed for different print jobs. In many cases a skip to the next
vertical tab could happen much faster than advancing individual lines,
so for fast printing, you'd carefully set up your carriage tape (or
electronic equivalent).

With most current printers, that's all pretty irrelevant.

Note that some printers (and display terminals) also allowed you to
set the horizontal tab stops (the now common "every eight" convention,
was not always the, *ahem*, convention).

 

[Al Balmer]

Mostly OT...

To expand on what John wrote, some (mostly older, and typically line)
printers could have vertical tab stops programmed. On some printers
this was actually done via a punched carriage tape (the tape was a
loop, with holes punched where the stops were desired). Those could
be changed for different print jobs.

Some people thought it amusing to substitute an unpunched tape.

 

[robertwessel2]

Some people thought it amusing to substitute an unpunched tape.

Or having the carriage tape break (for all the onlookers, either would
cause the printer to feed the entire box of paper through to the
stacker at the maximum rate possible).

I once worked for an extremely cheap shop. So cheap, that they
refused to buy the expensive (aka several dollar) mylar carriage
tapes. Instead, they discovered that if you cut out the paper
template (which you used to layout the carriage tape before punching
the "real" one), it would actually work in a 1403 printer. Of course
it would break regularly too, not to mention that the holes would ear
out (since the sensor was a brush), and the poor operators kept having
to restack boxes of "fed" forms...

They also refused to replace the punch itself after it broke, and for
months we had to cut the holes in the (paper) carriage tape with an
exacto knife. So the not exactly square and not exactly aligned holes
didn't exactly always trip the sensor... And they wondered why their
customers were always mad at them for messing up mailings.

 

[Barry Schwarz]

The fact that vertical tab and form feed exist both in the
basic source character set and the basic execution
character set suggests to me that there is a class of display
devices where vertical tab and form feed produce a predictable
and consistent (among different devices) behaviour. So what
are these devices and what is the behaviour ?

For old printers , form feed presumably moves to the next page
but vertical tab is a mystery to me.

Believe it or not, there still are a lot of dot matrix printers in use
that take pin feed paper. These printers accept "escape sequences"
which allow the application to define a bunch of properties, including
vertical tab stops. The application can then cause the paper to feed
forward to the desired position by including a vertical tab character
in the data sent to the printer. I see this most often at rental
agencies, auto dealer service centers, and other places where
multi-part forms are needed.


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