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Smooth Text mode scroll

i'm sorry if this is a FAQ, but i don't see it in the FAQ list.. :)

but how do i have smooth text mode scrolling (scanline thingy).. i have
downloaded and searched
the SWAG archive but have found no good source code that allows scrolling
of a text file up AND down..

hope you people in here can provide an answer?

Jeff

 

Re:Smooth Text mode scroll


Quote
Jeffrey wrote:
> i'm sorry if this is a FAQ, but i don't see it in the FAQ list.. :)

> but how do i have smooth text mode scrolling (scanline thingy).. i have
> downloaded and searched
> the SWAG archive but have found no good source code that allows scrolling
> of a text file up AND down..

> hope you people in here can provide an answer?

Go back to SWAG and look in TEXTFILE.SWG -- there are a couple there,
and I find the one written by Jon Merkel particularly interesting.

Quote
> Jeff

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Re:Smooth Text mode scroll


If you after scrolling of a text screen use the pascal inbuilt
procedures called

'insline' and 'delline'

Use Int 10h (Functions 06h and 07h) to program the BIOS to do this.

I mean its pretty smooth and pretty simple to use, i once made a
textreader with insline() and delline().

Re:Smooth Text mode scroll


In reading the other responses, I think they missed the question. What I
think he's asking for is
scrolling textmode 1 SCANLINE at a time, not your normal 16/14/8 scanline
scroll that BIOS normally
does. Due to the way video memory is configured in textmode this used to
be impossible. While I
haven't used a machine that does that in a long time I remember my DEC
Rainbow used to have an
option in it's Mode Command to allow this.

I think now that VGA is around, you could actually do this by copying the
system font to a user
font, rotating the ENTIRE FONTSET around once, and at the end do a normal
bios scroll. If you watch
the Retrace registers this could achieve the 'SMOOTH SCROLL' effect we
oldies remember.

I'll try to code this myself and post the results.

Re:Smooth Text mode scroll


Quote
DTHSHDW wrote:

[reformatted to make text readable]

Quote
> In reading the other responses, I think they missed the question. What I
> think he's asking for is scrolling textmode 1 SCANLINE at a time, not your
> normal 16/14/8 scanline scroll that BIOS normally does. Due to the way video
> memory is configured in textmode this used to be impossible. While I haven't
> used a machine that does that in a long time I remember my DEC Rainbow used
> to have an option in it's Mode Command to allow this.

No, smooth scrolling is indeed possible, both horizontally and
vertically.  Horizontal scrolling (technically, panning) is controlled
by the HPP (Horizontal Pixel Pan) register in the attribute controller
registers.  Vertical scrolling is controlled by the PRS (Preset Row
Scan) register in the CRTC registers.

Quote
> I think now that VGA is around, you could actually do this by copying the
> system font to a user font, rotating the ENTIRE FONTSET around once, and at
> the end do a normal bios scroll. If you watch the Retrace registers this
> could achieve the 'SMOOTH SCROLL' effect we oldies remember.

That's not really necessary, and isn't terribly efficient.  Also, it
doesn't really work.  ;-)

Quote
> I'll try to code this myself and post the results.

I did a little smooth scroll, but it really wasn't all that good.
There's much better source on the net if you're interested, but if you
can't find anything, I can send it to you.

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Scott Earnest        | We now return you to our regularly |
set...@ix.netcom.com | scheduled chaos and mayhem. . . .  |

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