[net.micro] Bidirectional/Proportional

jrt@hou5g.UUCP (02/02/84)

	1) Proportional printing can only be done by one of two methods.

	  a. The printer has a 'proportional print mode' - such as a Diablo.
		The printer needs to know which print wheel is attched, and
		advances the head according to the size of the printed
		character

	  b. If your printer has 'graphics' resolution, that is you can control
		the absolute positioning of the paper to within 1/100 of an
		inch.  This will require a software 'filter' for all printed
		files that would tell the printer..."print this char" and the
		"move to THIS location"

	  If your printer does not have the hardware capabilities to control
	it's head and paper to such fine degrees, you can NOT have proportional
	print.   NOTE: Proportional print is NOT a function of a printwheel.  It
	is a function of the hardware capabilities of the PRINTER!!!


	2) Bidirectional printing can ONLY be done in one of two methods/

	  a. The printer has the hardware to handle bidirectional printing.
		(see 1.a. above)

	  b. The printer has the hardware capabilities to address a particular
		column (see 1.b. above)

	Bidirectional printing is NOT a function of software.  It must
	be handled by HARDWARE.  

			(** FRODO **)

guy@rlgvax.UUCP (Guy Harris) (02/04/84)

>	Bidirectional printing is NOT a function of software.  It must
>	be handled by HARDWARE.

On some printers, however, it is not only a function of hardware (or, actually,
firmware; any one of the Diablo-type servo-controlled printers has the hardware
capability, but the micro controlling the printer may not have code to do
it) but also a function of the software controlling the printer.  The letter-
quality printers I've worked with of the Diablo-type servo-controlled family
(Diablo, NEC Spinwriter, Qume, etc.) could print backwards; however, the
host software had to position the head to the leftmost or rightmost position,
put the printer in "print forwards" or "print backwards" mode, and send the
characters in right-to-left order if printing backwards.

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy

ron%brl-vgr@sri-unix.UUCP (02/07/84)

From:      Ron Natalie <ron@brl-vgr>

Yes, just see Elizer Naddor, professor at Johns Hopkins and his
amazing Hebrew Diablo Wheel.

-Ron