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From: dan@rna.UUCP (Dan Ts'o)
Newsgroups: net.unix-wizards
Subject: Re: Pagination in TTY driver
Message-ID: <435@rna.UUCP>
Date: Sun, 25-Aug-85 14:02:46 EDT
Article-I.D.: rna.435
Posted: Sun Aug 25 14:02:46 1985
Date-Received: Tue, 27-Aug-85 01:45:41 EDT
References: <2067@ucf-cs.UUCP> <363@cuae2.UUCP> <2423@sun.uucp> <1392@cbosgd.UUCP> <5877@utzoo.UUCP> <280@frog.UUCP>
Reply-To: dan@rna.UUCP (Dan Ts'o)
Organization: Rockefeller Neurobiology
Lines: 49

In article <280@frog.UUCP> rfm@frog.UUCP (Bob Mabee) writes:
>{}
>(referring to novice and expert users of ls)
>> From *both* viewpoints, it is simpler to have pagination available in the
>> tty driver.  This means that the implementors don't have to kludge it into
>> every program, and the users need neither lightning reflexes nor high
>> sophistication.	 Try it, you'll like it.
>> -- 
>> 				Henry Spencer @ U of Toronto Zoology
>
>This sounds like a fruitful topic of discussion.  I would like to see this
>become a "standard extension" like file locking.
>
>Please tell us more about your user interface.  Do you require a Y every
>23 lines of output?  Only after 23 lines without intervening input (so
>you never notice pagination while running less verbose commands?

	Also:

		What about terminals that don't have 24 lines ? Some have
16 and some have 66 ? Do you have yet another ioctl() ?

		What happen when you print lines that wrap around the screen ?
Does the kernel know how to count character spacing, know the screen width,
whether the terminal has AM and XN and account for it when making page breaks ?

		The better pagers allow reverse and forward viewing. I find
this capability indispensible. Do you plan to add a buffer in the kernel to
allow reviewing of previous lines ?

		Does your implementation handle well situations where the
application is sending more than 24 lines but since it is using cursor
addressing, it is self consistent ? Does your kernel recognize cursor motion
sequences or do you have to turn off paging every time you run such an
application ? (e.g. graphics, some screen editors) Maybe you expect such
applications to run in RAW or CBREAK and don't do paging in those modes, or
maybe you expect such applications to shut off paging themselves.

		Yes, I know paging works fine for many situations.

					Cheers,
					Dan Ts'o
					Dept. Neurobiology
					Rockefeller Univ.
					1230 York Ave.
					NY, NY 10021
					212-570-7671
					...cmcl2!rna!dan
					rna!dan@cmcl2.arpa